Japan clears Herceptin for breast cancer - Roche

ZURICH, Feb 29 (Reuters) - Japan's health authorities have approved Roche's cancer drug Herceptin for the treatment of HER2-positive breast cancer, the Swiss drugmaker said on Friday.

HER2-positive breast cancer affects approximately 20 to 30 percent of women with breast cancer, the most common cancer among women worldwide, Roche said.

Each year more than 1 million new cases of breast cancer are diagnosed worldwide, and nearly 400,000 people will die of the disease annually, the firm said.

Herceptin, a humanised antibody, designed to target and block the function of HER2, a protein produced by a specific gene with cancer-causing potential, is marketed by Roche's subsidiary Chugai Pharmaceuticals in Japan.

For the company statement, click on:

http://www.roche.com/home/inv-update-2008-02-29

(Reporting by Sven Egenter; Editing by Erica Billingham)

Personalized Medicine Can Cut Breast Cancer Risk

(Ivanhoe Newswire) -- A leading cancer risk expert says it’s time for breast cancer assessment, counseling and genetic testing to become part of primary care.

Funmi Olopade, M.D., Walther L. Palmer Distinguished Service professor of medicine at Chicago Medical Center, says physicians now have enough information to help patients understand the consequences of genetic testing. “Referral for cancer-risk assessment and BRCA testing in the primary care setting is a necessary step towards personalized medicine for women at risk for breast cancer.”

Inherited mutations in the tumor suppressing genes BRCA1 and BRCA2 are currently the most powerful predictors of breast cancer. Dr. Olapade believes that primary care physicians should learn about the genetics of cancer risk, take a comprehensive history from patients and advise those who could be at risk about genetic testing and risk-reduction strategies.

Studies have shown that genetic counseling and testing do not cause adverse psychological effects. There is evidence that risk reduction is associated with breast or ovary removal in patients with the BRCA1 or 2 mutations. And now there are other preventive measures that include intensive screening and chemoprevention.

Dr. Olapade adds that there is still a lot we don’t know about these cancer-causing mutations. The frequency and impact in various ethnic groups is not well understood and conflicting results also cloud the picture. As a result many ethnic groups under use genetic testing. In addition, scientists are still finding new mutations of BRCA1 and BRAC2. “We do know that mutation of these genes is common in families with hereditary breast cancer and among young women with breast cancer,” Dr. Olapade was quoted as saying. “Our goal is to make this knowledge more and more available to patients and that has to begin in the primary care setting. Only then can we hope to reap the benefits of individualized medicine,”

Lady Raiders 'Think Pink' for breast cancer

The Lady Raiders participated in Think Pink to raise awareness and funds for breast cancer while basking in their victory over Western Kentucky University.

The game took place on Feb. 17 at 2 p.m. with the Lady Raiders displaying pink uniforms as a closing to the Think Pink week of 2008, which began on Feb. 8.

The pink uniforms were donated by Tommy and Dean Hodges and were auctioned off after the game to raise money for breast cancer research.

The Women's Basketball Coaches Association established the concept for Think Pink in 2007 to focus on the awareness of breast cancer in athletics and communities.

"We are just glad to be able to do our part [to raise awareness]," said Head Coach Rick Insell. "We are only one of 600 schools that are participating this year in order to raise funds."

In 2007, only 120 schools participated in the "Think Pink" campaign; however, as of now over 600 basketball teams have come together for the cause.

In attendance, fans wore pink to honor breast cancer survivors and support the WBCA and Kay Yow Cancer Fund. Actual members of the audience were recognized during halftime, along with a special video clip displayed on the scoreboard screens, presenting three breast cancer survivors.

"I am so pleased with the crowd and the excitement they brought to support our women's team and raise awareness for breast cancer," said President Sidney McPhee.

In addition to support, freshman guard Anne Marie Lanning and sophomore forward Brandi Brown both have family members that were diagnosed with breast cancer.

"I think it's good because it's helping a good cause and I feel like we're supporting something special," Lanning said.

After the game, each player's jersey was auctioned off with the proceeds going to the Kay Yow Cancer Fund, as well as the Middle Tennessee Medical Center.

"Everyone has just been more involved, and by coming out to see the game and the auction of the jerseys, everyone will be more aware that it can happen to them," Brown said.

Overall, Think Pink was a success with an attendance of 6,968 fans and an incredible $5,000 raised for sophomore guard Chelsia Lymon's pink jersey, which was ultimately the highest amount.

"I would love to see this as an annual tradition to continue to raise awareness for any kind of cancer including breast cancer," McPhee said.

Saliva test may be used to diagnose breast cancer –study

Forget about those unreliable, invasive and harmful tools currently used to diagnose breast cancer! U.S. researchers announced that they found a simple analysis of proteins in the saliva that can be performed in a dental clinic can determine whether the woman has the cancer.

The study published in the Jan 10, 2008 issue of the journal Cancer Investigation claimed that the test can not only diagnose breast cancer, but also help decide whether the subject needs surgery, a biopsy or a further testing.

Charles Streckfus, DDS, Professor of Diagnostic Sciences, The University of Texas Dental Branch at Houston. Photo credit: Natalie Wong Camarata
According to researchers at The University of Texas Health Science Center at Houston who conducted the research, the onset of breast cancer produces a change in the normal type of amount of proteins secreted from the salivary glands. A cancer can change the pattern.

Charles Streckfus, D.D.S., a University of Texas Dental Branch, an expert in salivary function and molecular epidemiology and William Dubinsky, a biochemist at The University of Texas Medical School at Houston and Lenora Bigler at the UT Dental Branch tested saliva samples from 30 patients and found that 49 proteins distinguished healthy people with a benign tumor from those who had malignant breast cancer.

The diagnosis was made possible using a so called “lab-on-a-chip" technology developed by biochemists at the University of Texas at Austin, which intends to bring the diagnostic procedure into the dental office and other health facilities to detect the presence of breast cancer before a tumor forms.

William Dubinsky, PhD, A biochemist and Professor of Integrative Biology and Pharmacology at The University of Texas Medical School at Houston. Photo credit: UT Medical School at Houston.
"Saliva is a complex mixture of proteins. We go through a process that compares different samples by chemically labeling them in such a way that we can not only identify the protein, but determine how much of it is in each sample," said Dubinsky.

"This allows us to compare the levels of 150-200 different proteins in cancerous versus non-cancerous specimens to identify possible markers for disease."

The concept is not new that the protein pattern in the saliva may be used to diagnose breast cancer. One study led by Carlson L. E. and colleagues from the University of Calgary and published in the Feb, 2007 issue of Journal of behavioral medicine revealed patients with breast cancer experience dysregulations in endocrine and sympathetic nervous systems and some proteins such as salivary cortisol is altered in the patients.

Breast cancer is diagnosed in about 200,000 American women and more than 50,000 die from the disease and complications of the conventional treatments. Worldwide, this disease will be found in an estimated 25 million women and kill 10 million in the next 25 years if no cure is found.

Current tools used to detect breast cancer include ultrasounds, regular blood test screenings, mammograms and biopsies some of which have received criticism from heath advocates because some procedures per se can increase risk of the cancer. The researchers said eventually all the diagnostic tools will be supplemented by salivary diagnostics.

MRI helps detect breast cancer early

KUWAIT (KUNA): The Second GCC Radiology Conference and Kuwait's Fifth International X-Ray and Radiology Conference discussed the latest techniques for early diagnosis of breast cancer, said conference chairman Dr Najib Al-Marzouq on Monday. In a press release, he said the conference, which kicked off on Saturday, looked into number of papers that tackled how MRI technology could be used to diagnose breast cancer and follow up cases that had been treated with chemotherapy.

Another paper dealt with surgeries for the extraction of breast tumors, as well as implementing a system of testing for those who had a history of this type of cancer in the family.
The conferees also discussed the need for training X-ray and radiology specialists on how to detect breast cancer, as well as alternatives for MRI and the role of radiology in diagnosing the condition and the phase it was at.
The Second GCC Radiology Conference and Kuwait's Fifth International X-Ray and Radiology Conference had kicked off on Saturday and concludes on Wednesday.

Online breast cancer information not always accurate: study

Most of the information about breast cancer found on the internet is accurate, but some of it can be misleading, says a new U.S. study.

The study by researchers at the University of Texas found that one in 20 breast cancer web pages contained information that was inaccurate. Sites focused on alternative or complementary medicine were 15 times more likely to have incorrect information, it found.

According to the study's authors, 44 per cent of women recently diagnosed with breast canceruse the Web to find health information.
Associated Press

According to the authors, 44 per cent of women recently diagnosed with the disease turn to the web to find health information.

The researchers evaluated 343 web pages using such criteria as display of authorship and the credentials of the identified authors and physicians, whether general disclaimers were provided, whether references were listed and the if date of the last update was posted.

They looked for breast cancer information using search engines such as Google, Yahoo, Alta Vista, Overture and AlltheWeb between June 1 and June 30, 2004.

The authors suggest people searching for breast cancer information online should be wary and look elsewhere to verify what they learn. "Consumers searching for health information online should still consult a clinician before taking action," reads the study.

The study is to be published in the March 15, 2008, issue of the journal Cancer.

Women back in court demanding a change of stance by the drug agency PHARMAC, over the drug Herceptin

11 February 2008
Eight breast cancer survivors have been back in the High Court In Wellington to challenge PHARMAC's decision over the funding of the drug Herceptin.

They are questioning the drug-buying agency's decision to fund Herceptin for just nine weeks instead of a full year for woman with Her2-positive cancer.

The Breast Cancer Aotearoa Coalition says thousands of lives depends on decisions made by PHARMAC, and women are becoming increasingly concerned about the way it reaches some decisions. They say the purpose of the Judicial Review is to find out how PHARMAC managed the advice it received about Herceptin and how its actions stacked up against its responsibilities.

Twenty-four OECD countries now fund the recommended 12-month treatment of Herceptin. The eight plaintiffs want PHARMAC to explain why it does not. They say it is out on a limb on its own.

The coalition is also concerned that future patients may find themselves in a similar situation. It says there are a large number of other new therapies on the horizon, and it would be unacceptable for another group of patients to go through the same issues, delays and inconsistencies women wanting the Herceptin treatment have endured.

This morning Justice Gendall granted their request for disclosure of documents the defence argued were commercially sensitive.

The case is expected to last a week.

Pharmac to fund breast cancer drug

Women with breast cancer now have another funded drug treatment available.

Under a new agreement Exemestane will be fully funded from August 1 without the need for a special authority approval.

Pharmac medical director Dr Peter Moodie says it is slightly different from Herceptin in that Herceptin is used in the initial treatment of breast cancer, whereas Exemestane is used for some years after the original chemotherapy.

Moodie says it works by blocking the growth of hormone-dependent tumours by lowering the amount of oestrogen in the body.

Walkathon raises people's awareness of breast cancer

NEW DELHI, Feb. 10 (Xinhua) -- Hundreds of people Sunday participated in a walkathon aimed at raising people's awareness of breast cancer here, Indo-Asian News Service reported.

Indian Prime Minister Manmohan Singh's wife Gursharan Kaur flagged off the campaign "Walk for Life", which was organized by a voluntary organization.

Indian Social Justice and Empowerment Minister Meira Kumar also joined the five-kilometer walkathon. "This walkathon is to create awareness among the women of India regarding breast cancer. The sooner one comes to know of the disease the easier it is to treat it," she said.

"Nearly one in every 22 women is a cancer patient and most terminal cases are of breast cancer," said Anjali, one of the organizers.

Anjali called on the Indian women to reject any taboo of speaking about breast cancer and have "an open and frank discussion of breast exams, treatment and life after cancer".

Breast cancer is the fourth largest killer disease in India and India accounts for 6 percent breast cancer deaths in the world.

Cancer

Cancer is a group of diseases in which cells are aggressive (grow and divide without respect to normal limits), invasive (invade and destroy adjacent tissues), and metastatic (spread to other locations in the body). These three malignant properties of cancers differentiate them from benign tumors, which are self-limited in their growth and don't invade or metastasize (although some benign tumor types are capable of becoming malignant). Cancer may affect people at all ages, even fetuses, but risk for the more common varieties tends to increase with age.Cancer causes about 13% of all deaths.According to the American Cancer Society, 7.6 million people died from cancer in the world during 2007.Apart from humans, forms of cancer may affect other animals and plants.

Classification

Nomenclature

The following closely related terms may be used to designate abnormal growths:

* Tumor: originally, it meant any abnormal swelling, lump or mass. In current English, however, the word tumor has become synonymous with neoplasm, specifically solid neoplasm. Note that some neoplasms, such as leukemia, do not form tumors.
* Neoplasm: the scientific term to describe an abnormal proliferation of genetically altered cells. Neoplasms can be benign or malignant:
o Malignant neoplasm or malignant tumor: synonymous with cancer.
o Benign neoplasm or benign tumor: a tumor (solid neoplasm) that stops growing by itself, does not invade other tissues and does not form metastases.
* Invasive tumor is another synonym of cancer. The name refers to invasion of surrounding tissues.
* Pre-malignancy, pre-cancer or non-invasive tumor: A neoplasm that is not invasive but has the potential to progress to cancer (become invasive) if left untreated. These lesions are, in order of increasing potential for cancer, atypia, dysplasia and carcinoma in situ.

The following terms can be used to describe a cancer:

* Screening: a test done on healthy people to detect tumors before they become apparent. A mammogram is a screening test.
* Diagnosis: the confirmation of the cancerous nature of a lump. This usually requires a biopsy or removal of the tumor by surgery, followed by examination by a pathologist.
* Surgical excision: the removal of a tumor by a surgeon.
o Surgical margins: the evaluation by a pathologist of the edges of the tissue removed by the surgeon to determine if the tumor was removed completely ("negative margins") or if tumor was left behind ("positive margins").
* Grade: a number (usually on a scale of 3) established by a pathologist to describe the degree of resemblance of the tumor to the surrounding benign tissue.
* Stage: a number (usually on a scale of 4) established by the oncologist to describe the degree of invasion of the body by the tumor.
* Recurrence: new tumors that appear a the site of the original tumor after surgery.
* Metastasis: new tumors that appear far from the original tumor.
* Transformation: the concept that a low-grade tumor transforms to a high-grade tumor over time. Example: Richter's transformation.
* Chemotherapy: treatment with drugs.
* Radiation therapy: treatment with radiations.
* Adjuvant therapy: treatment, either chemotherapy or radiation therapy, given after surgery to kill the remaining cancer cells.
* Prognosis: the probability of cure after the therapy. It is usually expressed as a probability of survival five years after diagnosis. Alternatively, it can be expressed as the number of years when 50% of the patients are still alive. Both numbers are derived from statistics accumulated with hundreds of similar patients to give a Kaplan-Meier curve.

Adult cancers

In the U.S. and other developed countries, cancer is presently responsible for about 25% of all deaths.On a yearly basis, 0.5% of the population is diagnosed with cancer. The statistics below are for adults in the United States, and may vary substantially in other countries

Childhood cancers

Cancer can also occur in young children and adolescents, but it is rare (about 150 cases per million yearly in the US). Statistics from the SEER program of the US NCI demonstrate that childhood cancers increased 19% between 1975 and 1990, mainly due to an increased incidence in acute leukemia. Since 1990, incidence rates have decreased

The age of peak incidence of cancer in children occurs during the first year of life. Leukemia (usually ALL) is the most common infant malignancy (30%), followed by the central nervous system cancers and neuroblastoma. The remainder consists of Wilms' tumor, lymphomas, rhabdomyosarcoma (arising from muscle), retinoblastoma, osteosarcoma and Ewing's sarcoma. Teratoma is the most common tumor in this age group, but most teratomas are surgically removed while still benign, hence not necessarily cancer.

Female and male infants have essentially the same overall cancer incidence rates, but white infants have substantially higher cancer rates than black infants for most cancer types. Relative survival for infants is very good for neuroblastoma, Wilms' tumor and retinoblastoma, and fairly good (80%) for leukemia, but not for most other types of cancer.

Cancer Signs and symptoms

Roughly, cancer symptoms can be divided into three groups:

* Local symptoms: unusual lumps or swelling (tumor), hemorrhage (bleeding), pain and/or ulceration. Compression of surrounding tissues may cause symptoms such as jaundice (yellowing the eyes and skin).
* Symptoms of metastasis (spreading): enlarged lymph nodes, cough and hemoptysis, hepatomegaly (enlarged liver), bone pain, fracture of affected bones and neurological symptoms. Although advanced cancer may cause pain, it is often not the first symptom.
* Systemic symptoms: weight loss, poor appetite, fatigue and cachexia (wasting), excessive sweating (night sweats), anemia and specific paraneoplastic phenomena, i.e. specific conditions that are due to an active cancer, such as thrombosis or hormonal changes.

Every symptom in the above list can be caused by a variety of conditions (a list of which is referred to as the differential diagnosis). Cancer may be a common or uncommon cause of each item.

Cancer Treatment

Cancer can be treated by surgery, chemotherapy, radiation therapy, immunotherapy, monoclonal antibody therapy or other methods. The choice of therapy depends upon the location and grade of the tumor and the stage of the disease, as well as the general state of the patient (performance status). A number of experimental cancer treatments are also under development.

Surgery

In theory, non-hematological cancers can be cured if entirely removed by surgery, but this is not always possible. When the cancer has metastasized to other sites in the body prior to surgery, complete surgical excision is usually impossible. In the Halstedian model of cancer progression, tumors grow locally, then spread to the lymph nodes, then to the rest of the body. This has given rise to the popularity of local-only treatments such as surgery for small cancers. Even small localized tumors are increasingly recognized as possessing metastatic potential.

Radiation therapy

Radiation therapy (also called radiotherapy, X-ray therapy, or irradiation) is the use of ionizing radiation to kill cancer cells and shrink tumors. Radiation therapy can be administered externally via external beam radiotherapy (EBRT) or internally via brachytherapy. The effects of radiation therapy are localised and confined to the region being treated. Radiation therapy injures or destroys cells in the area being treated (the "target tissue") by damaging their genetic material, making it impossible for these cells to continue to grow and divide. Although radiation damages both cancer cells and normal cells, most normal cells can recover from the effects of radiation and function properly. The goal of radiation therapy is to damage as many cancer cells as possible, while limiting harm to nearby healthy tissue. Hence, it is given in many fractions, allowing healthy tissue to recover between fractions.

Chemotherapy

Chemotherapy is the treatment of cancer with drugs ("anticancer drugs") that can destroy cancer cells. In current usage, the term "chemotherapy" usually refers to cytotoxic drugs which affect rapidly dividing cells in general, in contrast with targeted therapy (see below). Chemotherapy drugs interfere with cell division in various possible ways, e.g. with the duplication of DNA or the separation of newly formed chromosomes. Most forms of chemotherapy target all rapidly dividing cells and are not specific for cancer cells, although some degree of specificity may come from the inability of many cancer cells to repair DNA damage, while normal cells generally can. Hence, chemotherapy has the potential to harm healthy tissue, especially those tissues that have a high replacement rate (e.g. intestinal lining). These cells usually repair themselves after chemotherapy.

Targeted therapies

Targeted therapy, which first became available in the late 1990s, has had a significant impact in the treatment of some types of cancer, and is currently a very active research area. This constitutes the use of agents specific for the deregulated proteins of cancer cells. Small molecule targeted therapy drugs are generally inhibitors of enzymatic domains on mutated, overexpressed, or otherwise critical proteins within the cancer cell. Prominent examples are the tyrosine kinase inhibitors imatinib and gefitinib.

Immunotherapy

Cancer immunotherapy refers to a diverse set of therapeutic strategies designed to induce the patient's own immune system to fight the tumor. Contemporary methods for generating an immune response against tumours include intravesical BCG immunotherapy for superficial bladder cancer, and use of interferons and other cytokines to induce an immune response in renal cell carcinoma and melanoma patients. Vaccines to generate specific immune responses are the subject of intensive research for a number of tumours, notably malignant melanoma and renal cell carcinoma. Sipuleucel-T is a vaccine-like strategy in late clinical trials for prostate cancer in which dendritic cells from the patient are loaded with prostatic acid phosphatase peptides to induce a specific immune response against prostate-derived cells.

Hormonal therapy

The growth of some cancers can be inhibited by providing or blocking certain hormones. Common examples of hormone-sensitive tumors include certain types of breast and prostate cancers. Removing or blocking estrogen or testosterone is often an important additional treatment. In certain cancers, administration of hormone agonists, such as progestogens may be therapeutically beneficial.

Angiogenesis inhibitor

Angiogenesis inhibitors prevent the extensive growth of blood vessels (angiogenesis) that tumors require to survive. Some, such as bevacizumab, have been approved and are in clinical use. One of the main problems with anti-angiogenesis drugs is that many factors stimulate blood vessel growth, in normal cells and cancer. Anti-angiogenesis drugs only target one factor, so the other factors continue to stimulate blood vessel growth. Other problems include route of administration, maintenance of stability and activity and targeting at the tumor vasculature

Cancer Causes

Cancer is a diverse class of diseases which differ widely in their causes and biology. The common thread in all known cancers is the acquisition of abnormalities in the genetic material of the cancer cell and its progeny. Research into the pathogenesis of cancer can be divided into three broad areas of focus. The first area of research focuses on the agents and events which cause or facilitate genetic changes in cells destined to become cancer. Second, it is important to uncover the precise nature of the genetic damage, and the genes which are affected by it. The third focus is on the consequences of those genetic changes on the biology of the cell, both in generating the defining properties of a cancer cell, and in facilitating additional genetic events, leading to further progression of the cancer.

Chemical carcinogens

Cancer pathogenesis is traceable back to DNA mutations that impact cell growth and metastasis. Substances that cause DNA mutations are known as mutagens, and mutagens that cause cancers are known as carcinogens. Particular substances have been linked to specific types of cancer. Tobacco smoking is associated with lung cancer and bladder cancer. Prolonged exposure to asbestos fibers is associated with mesothelioma.

Ionizing radiation

Sources of ionizing radiation, such as radon gas, can cause cancer. Prolonged exposure to ultraviolet radiation from the sun can lead to melanoma and other skin malignancies.

Infectious diseases

Furthermore, many cancers originate from a viral infection; this is especially true in animals such as birds, but also in humans, as viruses are responsible for 15% of human cancers worldwide. The main viruses associated with human cancers are human papillomavirus, hepatitis B and hepatitis C virus, Epstein-Barr virus, and human T-lymphotropic virus. Experimental and epidemiological data imply a causative role for viruses and they appear to be the second most important risk factor for cancer development in humans, exceeded only by tobacco usage.The mode of virally-induced tumors can be divided into two, acutely-transforming or slowly-transforming. In acutely transforming viruses, the viral particles carry a gene that encodes for an overactive oncogene called viral-oncogene (v-onc), and the infected cell is transformed as soon as v-onc is expressed. In contrast, in slowly-transforming viruses, the virus genome is inserted, especially as viral genome insertion is an obligatory part of retroviruses, near a proto-oncogene in the host genome. The viral promoter or other transcription regulation elements in turn cause overexpression of that proto-oncogene, which in turn induces uncontrolled cellular proliferation. Because viral genome insertion is not specific to proto-oncogenes and the chance of insertion near that proto-oncogene is low, slowly-transforming viruses have very long tumor latency compared to acutely-transforming viruses, which already carry the viral oncogene.

Hormonal imbalances

Some hormones can act in a similar manner to non-mutagenic carcinogens in that they may stimulate excessive cell growth. A well-established example is the role of hyperestrogenic states in promoting endometrial cancer.

Immune system dysfunction

HIV is associated with a number of malignancies, including Kaposi's sarcoma, non-Hodgkin's lymphoma, and HPV-associated malignancies such as anal cancer and cervical cancer. AIDS-defining illnesses have long included these diagnoses. The increased incidence of malignancies in HIV patients points to the breakdown of immune surveillance as a possible etiology of cancer.Certain other immune deficiency states (e.g. common variable immunodeficiency and IgA deficiency) are also associated with increased risk of malignancy.

Cancer Prevention

Cancer prevention is defined as active measures to decrease the incidence of cancer. This can be accomplished by avoiding carcinogens or altering their metabolism, pursuing a lifestyle or diet that modifies cancer-causing factors and/or medical intervention (chemoprevention, treatment of pre-malignant lesions). The epidemiological concept of "prevention" is usually defined as either primary prevention, for people who have not been diagnosed with a particular disease, or secondary prevention, aimed at reducing recurrence or complications of a previously diagnosed illness.

Observational epidemiological studies that show associations between risk factors and specific cancers mostly serve to generate hypotheses about potential interventions that could reduce cancer incidence or morbidity. Randomized controlled trials then test whether hypotheses generated by epidemiological trials and laboratory research actually result in reduced cancer incidence and mortality. In many cases, findings from observational epidemiological studies are not confirmed by randomized controlled trials.

About a third of the twelve most common cancers worldwide are due to nine potentially modifiable risk factors. Men with cancer are twice as likely as women to have a modifiable risk factor for their disease. The nine risk factors are tobacco smoking, excessive alcohol use, diet low in fruit and vegetables, limited physical exercise, human papillomavirus infection (unsafe sex), urban air pollution, domestic use of solid fuels, and contaminated injections (hepatitis B and C).

Modifiable ("lifestyle") risk factors

Examples of modifiable cancer risk factors include alcohol consumption (associated with increased risk of oral, esophageal, breast, and other cancers), smoking (although 20% of women with lung cancer have never smoked, versus 10% of men), physical inactivity (associated with increased risk of colon, breast, and possibly other cancers), and being overweight (associated with colon, breast, endometrial, and possibly other cancers). Based on epidemiologic evidence, it is now thought that avoiding excessive alcohol consumption may contribute to reductions in risk of certain cancers; however, compared with tobacco exposure, the magnitude of effect is modest or small and the strength of evidence is often weaker. Other lifestyle and environmental factors known to affect cancer risk (either beneficially or detrimentally) include certain sexually transmitted diseases, the use of exogenous hormones, exposure to ionizing radiation and ultraviolet radiation, and certain occupational and chemical exposures.

Diet

The consensus on diet and cancer is that obesity increases the risk of developing cancer. Particular dietary practices often explain differences in cancer incidence in different countries (e.g. gastric cancer is more common in Japan, while colon cancer is more common in the United States). Studies have shown that immigrants develop the risk of their new country, often within one generation, suggesting a substantial link between diet and cancer.Whether reducing obesity in a population also reduces cancer incidence is unknown.

Despite frequent reports of particular substances (including foods) having a beneficial or detrimental effect on cancer risk, few of these have an established link to cancer. These reports are often based on studies in cultured cell media or animals. Public health recommendations cannot be made on the basis of these studies until they have been validated in an observational (or occasionally a prospective interventional) trial in humans.

Vitamins

There is a concept that cancer can be prevented through vitamin supplementation stems from early observations correlating human disease with vitamin deficiency, such as pernicious anemia with vitamin B12 deficiency, and scurvy with Vitamin C deficiency. This has largely not been proven to be the case with cancer, and vitamin supplementation is largely not proving effective in preventing cancer. The cancer-fighting components of food are also proving to be more numerous and varied than previously understood, so patients are increasingly being advised to consume fresh, unprocessed fruits and vegetables for maximal health benefits.

The Canadian Cancer Society has advised Canadians that the intake of vitamin D has shown a reduction of cancers by close to 60%,and at least one study has shown a specific benefit for this vitamin in preventing colon cancer.

Genetic testing

Genetic testing for high-risk individuals is already available for certain cancer-related genetic mutations. Carriers of genetic mutations that increase risk for cancer incidence can undergo enhanced surveillance, chemoprevention, or risk-reducing surgery. Early identification of inherited genetic risk for cancer, along with cancer-preventing interventions such as surgery or enhanced surveillance, can be lifesaving for high-risk individuals.

Vaccination

Considerable research effort is now devoted to the development of vaccines to prevent infection by oncogenic infectious agents, as well as to mount an immune response against cancer-specific epitopes) and to potential venues for gene therapy for individuals with genetic mutations or polymorphisms that put them at high risk of cancer.

As reported above, a preventive human papillomavirus vaccine exists that targets certain sexually transmitted strains of human papillomavirus that are associated with the development of cervical cancer and genital warts. The only two HPV vaccines on the market as of October 2007 are Gardasil and Cervarix.

Screening

Cancer screening is an attempt to detect unsuspected cancers in an asymptomatic population. Screening tests suitable for large numbers of healthy people must be relatively affordable, safe, noninvasive procedures with acceptably low rates of false positive results. If signs of cancer are detected, more definitive and invasive follow up tests are performed to confirm the diagnosis.

Screening for cancer can lead to earlier diagnosis in specific cases. Early diagnosis may lead to extended life, but may also falsely prolong the lead time to death through lead time bias or length time bias.

A number of different screening tests have been developed for different malignancies. Breast cancer screening can be done by breast self-examination, though this approach was discredited by a 2005 study in over 300,000 Chinese women. Screening for breast cancer with mammograms has been shown to reduce the average stage of diagnosis of breast cancer in a population. Stage of diagnosis in a country has been shown to decrease within ten years of introduction of mammographic screening programs. Colorectal cancer can be detected through fecal occult blood testing and colonoscopy, which reduces both colon cancer incidence and mortality, presumably through the detection and removal of pre-malignant polyps. Similarly, cervical cytology testing (using the Pap smear) leads to the identification and excision of precancerous lesions. Over time, such testing has been followed by a dramatic reduction of cervical cancer incidence and mortality. Testicular self-examination is recommended for men beginning at the age of 15 years to detect testicular cancer. Prostate cancer can be screened using a digital rectal exam along with prostate specific antigen (PSA) blood testing, though some authorities (such as the US Preventive Services Task Force) recommend against routinely screening all men.