Cancer is now emerging as a major public health problem in developing countries, matching its effect in industrialized countries. In developing countries, including India, oral cancer is the most common cancer in males and breast cancer in females. However cervical cancer remains the most common cancer in rural women. Lung cancer remains the second most common cancer in both males and females. This steady increase in incidence of cancer is mainly due to an increase in aging population and current trends in smoking and unhealthy life style habits across the globe in both developing and developed countries.
Epidemiological studies have shown that 70-90% of all cancers may have an impact of environmental hazards. Lifestyle related factors are the most important and the most preventable among the environmental exposures. Tobacco consumption either as chewing tobacco or smoking tobacco accounts for 50% of all cancers in men. Unhealthy dietary practices and reproductive and sexual practices account for 20-30% of all cancers. Appropriate changes in lifestyle can, therefore, reduce the mortality and morbidity from a good proportion of cancer and heart diseases.
Diet and Cancer
Most of the cancers have some relationships with diet, predominant among them being cancer of the upper aero digestive tract (mouth, throat etc), esophagus (food pipe), lungs, stomach, large intestine, and breast cancer in women to some extent.
The role of diet takes special importance in countries like India which are fast moving towards industrialization and westernization. This coupled with other habits like smoking and alcohol abuse will lead to increase in the chronic disease burden especially in cancer and cardiovascular diseases. Prompt action has to be taken to spread the message of a healthy life style and good dietary practices.
The main risk factor for cancer of the mouth and throat is consumption of tobacco and alcohol. Although tobacco both in smoked and chewed form is responsible for oral and throat cancers, alcohol has a synergistic effect along with tobacco products. A diet rich in green and yellow vegetables has been shown to offer protection against oral cancer. Avoidance of tobacco and alcohol is however the most important preventive action against mouth, throat and lung cancers. Consumption of large amounts of red chillies, food at very high temperatures and alcohol consumption are the main risk factors for stomach cancer. Heavy consumption of red meat can lead to risk of colon cancer. White meat such as that of poultry does not have this risk.
Lifestyle and Cancer
A large number of factors have been identified as risk factors for breast cancer. Menarche at an early age, first pregnancy at a late age, that is more than 30 years, having a single child, nulliparity, and menopause at late age increase the risk of developing breast cancer. In postmenopausal women, obesity and postmenopausal hormone replacement therapy are associated with increased breast cancer risk. A high fat diet is also identified as a risk factor. Physical activity is found to be protective for breast cancer. There may be a moderate protective effect of vegetable consumption. There appears to be a definite association between alcohol and breast cancer risk, with the risk increasing with the amount of alcohol consumed. Decreased intake of nutrients such as vitamin C, folic acid, and beta carotene may enhance the risk related to alcohol consumption. Obesity is associated with both an increased risk of breast cancer development in postmenopausal women and increased breast cancer mortality. Long-term use of hormone replacement therapy in post-menopausal symptoms (estrogen-progestin combinations) increases the risk of development of breast cancer in women. There is however no evidence of any link between use of birth control pills and breast cancer risk.
Having a first intercourse at an early age, having multiple sexual partners, keeping poor sexual hygiene and having repeated child births are some of the reproductive risk factors for cervical cancer. Improvements in the living standards of women have resulted in a reduction in the incidence of cervical cancer. Regular cervical cytology examination (pap smear) by all women who have initiated sexual activity can help in detecting of cervical cancer.
Hygiene and Cancer
There is definite evidence of association between poor personal hygiene and cervical cancer in women and penile cancer in men. Most of the evidence supports a high incidence of HPV infection in penile cancer patients. HPV is a virus which is transmitted from skin to skin contact during sexual intimacy. Persistent HPV infection may lead to several premalignant changes further increasing the risk of cancer if left untreated. Other risk factors for penile cancer include smoking, having an age of more than sixty years, and AIDS. Personal hygiene in the genital area is very important. Oily secretions, dead skin and bacteria which can build up under the foreskin (known as smegma) can lead to persistent infection and irritation leading to premalignant changes and development of carcinoma penis. Some of these risk factors can be avoided.
HPV has the strongest link with cervical cancer development. It is an extremely common virus that is transmitted through sexual contact. Studies have shown that smoking can accelerate the cervical damage caused by HPV. Having many sex partners or having sex with someone who has had many sex partners may increase the risk further. Having sex at an early age also increases the risk for cervical cancer.
Physical Activity and Cancer
In addition to other health benefits, physical activity can also affect the risk of cancer. There is convincing evidence that physical activity is associated with a reduced risk of cancers of the colon and breast. Several studies have also reported links between physical activity and a reduced risk of cancers of the prostate, lung and endometrial cancer.
Colorectal cancer has been the most extensively studied cancer in relation to physical activity. Several studies have shown a consistent association between increase in physical activity either in intensity, duration, or frequency leading to a reduced risk of developing colon cancer by 30-40 percent, relative to those who are sedentary, regardless of their body mass index (BMI). The protective effect appears greatest with high-intensity activity, although the optimal exercise levels and duration are still difficult to determine. The association of physical activity with breast cancer incidence has been extensively studied and over 60 studies have indicated that physically active women are at lower risk of developing breast cancer than inactive women; however the amount of risk reduction achieved through physical activity varies widely between 20-80%. There is also an inverse association between physical activity and endometrial cancer incidence, however the evidence is not as strong as the positive effect found for breast cancer.
Points to Remember
- Promote the use of a vegetarian diet. Use plenty of fresh fruits and green vegetables. Wash fruits and vegetables thoroughly before consumption.
- Stop use of tobacco (smoking and chewing) and alcohol
- Physical activity (a brisk walk for at least 20 minutes a day) is desirable. Yoga can complement physical activity/exercise. Keep your weight in check.
- Keep small family norms and breast feeding of babies. Have timely marriage and Avoid hormone replacement therapy after menopause.
- Practice monogamy and maintain sexual hygiene.