Lung Cancer PART – 1 – Etiology


(All the articles published in past are available at

Question: Thank you Chiragbhai for covering Head and Neck cancers comprehensively, in a very simple language, in 14 parts. It was very helpful to broadly understand how different sites in this region differ from each other, role of surgery, role of chemoradiation combination in replacing surgery for many sites, importance of strict follow up, high risk of recurrence in other sites due to field carcinogenesis by tobacco exposure, issues in long term care, and above all importance of prevention by avoiding tobacco gutkha alcohol altogether, and ensuring our children do not fall prey to this dangerous habit. You have nicely covered cancer prevention in your book also, titled “Cancer Can Be Cured” or in Gujarati “Cancer Mati Shake Che”.
Ans: Thank you. Now we are going to discuss another major tobacco related cancer – LUNG CANCER. As our readers would be aware, tobacco smoking is responsible for about 80-90% of lung cancers.
Que: Yes I am sure they are aware, but we see few patients who have never smoked. How does that happen? And also the fact that everyone who smokes does not develop lung cancer.
Ans: Let us start with your second point. Yes, everyone who smokes does not develop lung cancer, but it is well known from several studies that there is a clear relationship between risk of lung cancer and number of cigarettes smoked and number of years of exposure.
With 40 years of smoking one pack per day, risk increases by 20 times, compared to a never smoker.
It is also known that if person quits smoking, his risk reduces significantly in 5 years, and by 15 years there is 90 percent reduction. So someone who says that I am smoking because I know people who are smoking but have not developed lung cancer, is clearly taking a big risk. Something like driving a bike very rash, not wearing helmet and saying I am still alive! Also, do remember that lung cancer is frequently detected late, in incurable stage. It is one of the top causes of cancer deaths in India and world.
In addition, smoking is the reason for many heart attacks, debilitating lung problems, infertility, and many other disorders. A person who smokes around others, also puts his family, friends, colleagues in danger due to risk of lung cancer from passive smoking. Children are much more susceptible. All forms of tobacco smoking including cigar, pipe etc also increase risk.
Following factors are known to modify risk of developing lung cancer in a person who smokes:
1. Genes – different people have different susceptibility. Family history increases risk.
2. Diet – diet rich in fruits and vegetables seems to reduce risk. However, vitamin or herbal supplements do not reduce risk. In fact, high dose beta carotene supplement was found to increase risk of lung cancer in smokers. Poor nutrition in many Indians is a potential risk factor why so many younger patients develop these cancers.
In response to your first question, why do some non smokers develop lung cancer:
1. In about 20% cases, and likely higher in India, smoking tobacco is not the reason. In women, it is about 50% cases. In many cases, there is no clear known etiology.
2. Biggest known reasons in this category are AIR POLLUTION and Use of WOOD or COAL for cooking or home heating.
3. Other risk factors for lung cancer include asbestos exposure, radon gas exposure, and various other factors – all of these account for a much smaller number of cancers.
4. A well known additional factor is second hand smoke. Various studies have varying estimates of how much risk increase happens due to second hand smoke. But it is prudent to avoid that. This is especially true for children or young people whose risk increases a lot more.
Que: Thank you for clarifying both points. But tobacco is very addictive. How can a person get rid of smoking habit or how can we help such people?
Ans: Yes indeed it is difficult to get rid of this habit. But it is definitely worth trying. Even if a person reduces consumption of tobacco, there is significant benefit. It has been shown in studies that a doctor’s advice to reduce tobacco use or quit use completely, has benefits and it works for a small but significant number of people. Many people are able to quit based on their faith, such as taking decision in a temple or in front of their Guru. Several spiritual religious leaders in India have helped large number of people to quit. A very recent study published in annals of internal medicine also suggested that complete quitting on a chosen date, instead of gradual reduction, has better success rates. For people who wish other options, experts are available to consult and use of nicotine replacements to help them quit or reduce tobacco use.

March 12th 2016.

Dr. Chirag A. Shah; M.D. Oncology/Hematology (USA), 079 26754001. Diplomate American Board of Oncology and Hematology. Ahmedabad.                                                                                                                                                       Shyam Hem-Onc Clinic. 402 Galaxy, Near Shivranjani, Opp Jhansi ki Rani BRTS, Ahmedabad.