This is the final article in the lung cancer awareness series by Dr. Ashok Komaranchath. While many strides are being made in cancer screening and treatment, Dr. Ashok stresses that prevention will always remain the more viable and economically feasible option for those at risk.

We have previously discussed about the incidence, causes, demographics, symptoms investigations and treatment of lung cancer. But will we ever be able to cure it? The answer is a probable no. However, the old proverb holds true here as well- Prevention is better than cure. In this case, it is easier than finding a cure for the many and varied molecular subtypes of lung cancer.

How can we prevent lung cancer?

Our professor used to say that the most important cause of lung cancer is smoking. The second most important cause is smoking and the third most important cause is also smoking. Drastic reductions in the level of smoking (both primary and second-hand smoke) will bring down the incidence of lung cancer in the community as a whole. This has been seen vividly in several European nations where the incidence of smoking in adults has reduced drastically over the past 30 years and have concurrently shown a reduction in not only lung cancer incidences and deaths; but also reductions in cardiovascular mortality and other smoking related causes of death.

Most governments now levy hefty fines on sales of cigarettes, have banned smoking in public, deployed graphic labels on tobacco products showing the detriments of smoking and even insurance companies charge different premiums for smokers versus non-smokers. There are smoking cessation clinics, with nicotine substitutes like chewing gums, lozenges and patches which help people to stop smoking. For heavy and long-term smokers, one may need medications like buprenorphine and psychosocial counselling.

Along with smoking cessation, environmental pollution also has to be stopped or reduced drastically. The use of smoky choolas for cooking in under-developed places like rural India has to be phased out and cleaner sources of energy like LPG has to be introduced. Pollution in large cities like New Delhi have become so untenable that scientists say that just breathing the air is equal to smoking 33 cigarettes a day! Switching to greener energy sources at home and work, judicious use of electrical appliances and increased use of mass transportation all help in reducing our carbon footprint.

A common question asked to oncologists the world over is what sort of diet can prevent or help to treat cancer. The hard truth is that there is no single diet or supplement which has ever been proven to prevent or treat any cancer. The simple truth is that any healthy diet, with correct proportions of proteins, carbohydrates, fats and nutrients is the ideal one we must all follow.

The only dietary products definitively implicated in cancer formation is processed meats (like sausages, salamis, preserved and/or salted meat products). This has been classified as a Group 1 carcinogen (Definitely causes cancer) by the International Agency for Research on Cancer (IARC), an organisation which keeps watch on all products and processes which may cause cancer in humans. Red meat (all mammalian muscle meat, including beef, veal, pork, lamb, mutton, horse, and goat) is classified as Group 2A (probably carcinogenic to humans).

This classification is based on limited evidence from epidemiological studies showing positive associations between eating red meat and developing colorectal cancer as well as strong mechanistic evidence.[1] We routinely recommend avoidance of processed foods and limiting the amount of red meat in one’s diet. However, the benefit of avoiding processed meat and red meat has been primarily linked to colorectal cancer and not lung cancer. If one eats a very healthy vegetarian diet but smokes 30 cigarettes a day, it is very likely that one will die from a heart attack or lung cancer but the colon will be in fine condition.

There is not a single dietary inclusion that has been conclusively proven to prevent cancer. This indeed sounds boring and unbelievable which is why social media is filled with ads about ‘super-foods’ and ‘lemons are cancer fighters’ and plenty of charlatans preying on susceptible minds.

Screening in lung cancer

The maximum possibility of ‘cure’ in any cancer depends on the stage at diagnosis. For every single cancer, it is a given that ‘Stage-1’ will have higher cure rates than ‘Stage 3 or Stage 4’. Some cancers can be detected early by mass screening programs, even in a pre-clinical stage, which nearly guarantees a cure. Examples include cervical cancer, breast cancer and colorectal cancers.

Since lung cancer is an insidious and particularly aggressive cancer, it was thought to be impossible to device a safe, cheap, effective and accurate method of screening. Several chest X-ray screening programs in high-risk populations like heavy smokers or industrial workers were done for lung cancer in the 1970’s-80’s but failed to pick up enough cases early enough to make a difference. CT scans were an option but at the time, were too expensive to make it economically feasible.

In 2011, the NLST trial was published in NEJM. It enrolled over 50,000 participants at high-risk of developing lung cancer and performed a yearly ‘Low-Dose CT thorax’ for 3 years. The trial was stopped prematurely as it was found to have a significant benefit in early detection of lung cancer with a 20% relative mortality reduction and a 6.7% reduction in all-cause mortality.[3]

This benefit of low-dose CT scan screening has been confirmed by subsequent trials like the NELSON trial and the DANTE trial. Today, most western countries recommend annual low dose CT thorax to all individuals between 55 and 74 years of age with a 30-pack year smoking history.

What does the future hold?

The next few decades promise to be the most exciting yet in the field of cancer research. There are potential blood tests which can detect even a single DNA strand from a cancer cell (Circulating Tumour DNA - ctDNA) and tell us where it came from, what sort of mutations are driving the cancer and how to destroy it even before the cancer is large enough to appear on our current best imaging modalities. The quality of imaging itself is improving with leaps and bounds and the line between imaging and treatment is blurring with some imaging machines able to deliver therapeutic molecules also, leading to an entirely new field called theranostics. There are ways to sequence DNA so quickly that an unknown novel coronavirus was isolated and the entire genome sequenced in a matter of weeks.

Human whole genome sequencing is not far from being commercialised and may be potentially used to tailor make treatments for each cancer patient for maximum effectiveness. Even with all these developments, a complete cure of any one cancer is still probably more than a lifetime away, let alone for all cancers. But there is no doubt that patients diagnosed with cancer today will outlive those diagnosed with the same cancer and stage just a decade prior.

To read other articles in this series, click,

Lung cancer- Not a single disease

Lung Cancer: The common clinical presentation and work-up for primary care

SCLC & NSCLC staging and treatment: What are the variables to be considered?

Disclaimer- The views and opinions expressed in this article are those of the author's and do not necessarily reflect the official policy or position of M3 India.

The author, Dr. Ashok Komaranchath is a Medical Oncologist from Kerala.