Cancer Prevention

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Cancer conjures up images of mutilating surgery, chemotherapy, radiation, years with doctors and in hospitals, and — most terrible — death. It comes in many avatars and can attack any part of the body. The risk factors for the ailment are many. It has been found to have associations with infections, lifestyle, genetic factors and heredity. If an injection is available to prevent cancer, it is hard to imagine anyone opting not to take it!

Viruses have long been known to cause infections that can progress to cancer. Previously, the association was suspected but not proven. Today, with electron microscopes, DNA sequencing and other advanced techniques, the association between certain viral infections and cancer has been conclusively proven. Of these, two types of cancer — of the cervix and some cancers of the liver — can be prevented with timely immunisation.a

The statistics speak for themselves. Cervical cancer (or cancer of the neck of the uterus) accounts for 25 per cent of all cancers in women. It is commoner than breast cancer (14 per cent). Around 1,30,000 cases are detected annually in India and half of these women eventually succumb to the disease.

Cervical cancer has long been associated with certain risk factors. It is more likely to occur if the woman smokes, does not have a healthy diet with plenty of fruits and vegetables, is exposed to multiple male sexual partners, has her first sexual contact before the age of 17 years, or has multiple pregnancies. A higher incidence is also noted if the woman has other sexually transmitted infections like Chlamydia or infection with HIV.

Recently, the association between infection with HPV (Human Papilloma Virus) and cervical cancer has been conclusively established. More than 95 per cent of the women with cervical cancer have evidence of HPV infection. Although 75 per cent of normal women have evidence of HPV infection, the virus persists and goes on to cause cancer in 5-10 per cent.

There are 130 identified types of HPV. Some cause infection but produce no symptoms like fever or pain, and are harmless. The patient may remain totally unaware of the infection. Other subtypes of HPV may cause warts on the skin. Around 30-40 types of the virus is transmitted through sexual contact. They may produce no symptoms when the infection first occurs. The virus can persist in the surface mucosa of the moist ano-genital areas. It can produce disfiguring warts in these areas. It can extend into the vaginal areas and cervix. Cancerous changes occur 20-30 years after the initial infection, when the woman is in her 40s and 50s.The progression depends on the type of virus and is more likely to occur if the infection occurred with the subtypes 15-20.

Once the association between cervical cancer and HPV was established, the scientific community got to work and produced a vaccine. It has been extensively studied and is now marketed in India by two companies under the trade names “Gardasil” and “Cervarix”. This is a major scientific breakthrough and cervical cancer can now be prevented in future generations of women.

The dosage schedule advised for HPV vaccine is as follows. The first dose is given between nine and 11 years of age. The second dose is administered two months later, and the third six months after that. No booster doses are advised at present. Women who have not been immunised can have the first dose at any time up to the age of 26 years. If they have already been exposed to HPV, the vaccine will only protect them against the strains to which they have not been exposed. Immunisation is not advised in pregnancy but can be given to breast-feeding mothers. Side effects are rare and include fever and rash.

For those of us who are older and have not had access to the vaccine, a screening test called “pap smear” (Papanicolaou test) can be done to detect cervical cancer in its early stages. The test is widely used and is effective. Screening should ideally be done three years after sexual activity has started and then continued every three years after that. Many Indian women do not have access to this test or are unaware of it.

Liver cancer and chronic liver disease can occur in people who develop hepatitis B infection. This too is a viral disease which is spread by contact with infected body fluids (blood transfusions, sexual intercourse). Infection can be prevented by three doses of hepatitis B vaccine. The second dose is given a month after the first and the third six months later.

Men and women should receive immunisation against Hepatitis B. At present, HPV vaccine is advised only for girls. Perhaps we have forgotten that women get the infection from their infected male partners, making a case for non-gender specific universal immunisation of all children.

Source: The Telegraph (Kolkata, India)