In view of the ongoing Lung Cancer awareness month, we bring to you a write-up on lung cancer and a quick primer on the recent advances being made in the investigation and treatment of the disease. Dr. Ashok Komaranchath delivers a quick read on the history and understanding of the disease, along with strides being made in the management of it.

Click to read other articles from Dr. Ashok Komaranchath.

To call lung cancer a dreaded disease would be an understatement

For most oncologists, seeing a definitive chest X-ray is akin to seeing the spectre of the grim reaper himself. It has struck down people from all walks of life. From kings (King George-VI) and vagabonds, rock stars (George Harrison of The Beatles) to movie stars (John Wayne), corporate giants (Walt Disney) to talk show hosts (Larry King) to 1.76 million others every year.

Incidence of this began to rise steeply after the start of the 20th century once smoking became more mainstream and fashionable. Until the seminal work of Doll and Hill in the 1950s and the US surgeon general’s warning linking smoking and lung cancer, it was regarded as a harmless pastime with even some doctors endorsing the same! After a steady climb, through most of the 20th century, lung cancer rates had started decreasing only in the 1990’s corresponding to a decrease in smoking rates in most developed nations. However, It is still the number one cancer in both incidence and cause of death worldwide.

The extent of smoking seems to have a linear correlation with the risk of developing lung cancer. A common cut-off asked for while taking history is the 20-pack year history. Described first in the west, it means that the person must have a history of smoking a 20-cigarette pack every day for 20 years or more. As we all know, smoking not only gives rise to lung cancer but nearly a dozen other cancers and multiple other systemic problems like cardiovascular and cerebrovascular events.

Lung cancer- Not a single disease

The understanding of this terrible disease has grown by leaps and bounds in the past few decades. Just as cancer isn’t a single disease, lung cancer also is many types of diseases within a general disease classification. Most of us know that our pathology texts have taught us there as different histologies within lung cancer. The major division is given as small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). The latter is further divided into adenocarcinoma, squamous cell carcinoma and large cell carcinoma. The latest molecular and genomic profiling of lung cancers have brought about even more subdivisions under these. The importance of this is that, each of these subtypes behave differently, respond to different treatments in different manners and have significantly different outcomes.

Similarly, the clinical presentation of this disease may vary from the classic, persistent, hacking cough with haemoptysis to a nagging, deep-seated bony pain or sudden onset seizures from bone or brain metastases respectively. One patient of mine presented with sudden loss of vision and no respiratory complaints. It turned out to be a choroidal metastasis from a silent primary lung cancer in a non-smoking female! The clinical presentation will be discussed in detail in the next article.

Updates in investigation and pathology

Investigations have also changed over the years from the quintessential chest X-ray to CT scans to the newest subspecialty of nuclear medicine with technetium bone scans and 18-FDG PET-CT scans. Pathology has pushed the boundaries even further, with different specialised staining techniques callediImmunohistochemistry (IHC) to genetic analysis of specific mutations within the cancer cell (Exon 19 mutations of the EGFR oncogene) to molecular assays of cell surface proteins like Programmed Death-Ligand 1 (PD-L1). Nearly every day, there are new discoveries that further our understanding about the pathogenesis of lung cancer and thereby give us new tools and weapons in our armamentarium which can specifically target genes and pathways that help us stop this cancer from growing or spreading. But, even with this avalanche of information, like the proverbial iceberg, it seems like we have only scratched the surface of the myriad mechanisms and pathways of cancer and lung cancer in particular.

Treatment advances

Keeping with the breakneck pace of inventions and discoveries in the field of medicine, oncology seems to command a large share of research and clinical trials especially in drug discovery. The number of oncology medicines available for any given cancer is rising exponentially. This leap in funding is largely covered by the exorbitant costs of many of these new medications. This has led to many cutting edge technologies and medications being put out of the reach of many people and certainly a large section of population in a developing country like India. Nevertheless, the impact of these new discoveries cannot be understated. Cancers that could not be cured 20 years back are being cured today. Cancers that were virtually guaranteed death in months a few years back, now have patients living for years.

In lung cancer too, advances have come in leaps and bounds. With the advent of a new form of treatment called immunotherapy, the dismal survival rates of stage IV lung cancer which saw little change over decades, saw a 26% increase in 5-year-survival over just a decade (from 2009-2019). New molecular targets like EGFR, ALK and ROS1 (among many more) have given multiple oral preparations which have been proven to be as, if not more effective than conventional chemotherapy in those particular subset of patients. Advances in surgery and the advent of robotic surgery has opened avenues of potential resectability in hitherto unresectable lung tumours.

As with all formidable illnesses, prevention is always better than cure, especially when the cure is as elusive as that in lung cancer. Stopping smoking at any point of time carries tremendous health benefits, not only with respect to lung cancer.

One year after quitting, the risk of coronary artery disease is half that of a smoker’s.

1. In 5-10 years, the risk of stroke is almost the same as a non-smoker.
2. At 10 years, the risk of lung cancer is half that of a smoker.
3. At 20 years after quitting, it even approaches that of a non-smoker.

Hence, smoking cessation is the single most important health intervention which can be implemented in the fight against cancer.

This article is the first of four concerning lung cancer. In the coming articles, we will discuss

• The common clinical presentation
• Investigations
• Treatment options
• Future trends in lung cancer

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.