Considered largely a disease of elderly smoking men till 20 years back, lung cancer incidence is now increasing steadily among Indian women as well as non-smoking men, say India’s leading medical experts.
While breast cancer remains the leading cancer afflicting women, the incidence of lung cancers are also rising in the fairer sex. However, low survival rates as compared to breast cancer makes lung cancer deadlier in women. In India, lung cancer constitutes 6.9 per cent of all new cancer cases and 9.3 per cent of all cancer related deaths in both sexes, says Dr Muzammil Sheikh, Medical Oncologist, Hinduja Hospital, Mumbai.
Dr. Anil Heroor, Head of Department of Surgical Oncology, Fortis Hospital Mulund and Kalyan, says the incidence is increasing in both men and women but the number of women reporting lung cancer has markedly increased as compared to 10 years back.
Common causes attributable to this trend are increase in incidence of smoking in women, exposure to second-hand smoke at home, and other environmental hazards including air pollution. Smoking is the most important risk factor which is said to be responsible for almost 80 to 90 percent of lung cancers. Other factors like passive smoking, exposure to asbestos, radon, metals (arsenic, chromium, and nickel) and radiation are some which may lead to lung cancer, says Dr Heroor.
Yet, more than half of the non-smokers who report lung cancer are women, pointing to the fact that apart from environmental and lifestyle factors, biological and genetic differences between men and women also play a role in susceptibility to lung cancer and the risk of dying from it.
Dr Sheikh says some researches have indicated that female hormone estrogen may help certain lung cancer cells to grow and spread throughout the lungs. This may aid the growth of lung cancer in non-smoking women.
There is also difference in the way lung cancer manifests in men and women. Just as a heart attack manifests differently in men and women, lung cancer too often displays different symptoms in men and women. While the types of lung cancers common in men display more easily identifiable symptoms such as violent cough or coughing of blood, the types of lung cancers usually found in women show more vague symptoms in the initial stages. By the time most women are diagnosed with lung cancer, it has already spread to other organs, points Dr Sheikh.
Adenocarcinomas of the lung (a type of non-small cell lung cancer) are one of the most common types of cancers found in women as well as in non-smokers. These cancers tend to develop on the outer regions of the lungs, and therefore often spread to other parts of the body before showing clear symptoms. The initial symptoms that occur is these types of cancers are usually vague such as general fatigue, pain in the back or shoulders.
A large share of non-smoking patients is also women who might have had exposure to second hand smoke all their lives at home. Second hand smoke or the smoke inhaled by a non-smoker inadvertently from his/her surroundings is basically environmental tobacco smoke which constitutes two streams. First is the mainstream smoke or the smoke exhaled by the person smoking a cigarette.
The other form is sidestream smoke that emanates from the lighted end of a cigarette or cigar. The latter is more toxic and has higher concentration of carcinogens, according to American Cancer Society. The particles constituting sidestream smoke are also smaller compared to mainstream smoke and can easily make way into the lungs, explains Dr Heroor.