Increasing trend of NSCLC among never-smokers prompts new research efforts

Twenty percent of lung cancer cases in the United States are diagnosed in people who never smoked.

This translates to between16,000 and 24,000 Americans annually, according to the American Cancer Society. The majority of these cases are non–small cell lung cancer.

Although the exact cause for increased proportion of lung cancer cases among never-smokers has not been established, researchers suggest environmental factors may to be blame.

However, they emphasize more data are needed to identify the factors that are driving the increase ― and determine the most appropriate treatment options for never-smokers ― before changing practice.

HemOnc Today asked Lorraine Pelosof, MD, about her research efforts conducted while she was an assistant professor at University of Texas Southwestern that examined NSCLC rates among never-smokers ― including findings she presented last fall at the 16th World Conference on Lung Cancer ― and what, if anything, can be done to stop the trend.

Question: How common is lung cancer among nonsmokers?

Answer: An estimated 10% to 15% of lung cancer cases occur in never-smokers. Lung cancer in never-smokers has been associated with patients of East Asian descent and female sex, though it does not always fit this pattern. Causes of lung cancer in never-smokers include many possible factors, such as radon and air pollution, but the precise cause in an individual patient is often not known.

Q: What do the trends suggest about incidence?

A: Based upon our data, where we looked at three different institutions in our area, it looks like the trend for non–small cell lung cancer among never-smokers is increasing. However, in small cell lung cancer, the rate is stable. This is most likely because this type is almost 100% attributed to tobacco. The increase that we observed was in NSCLC. On average — during the course of our study, between 1990 and 2013 — the percentage of patients with NSCLC across all three institutions who were never-smokers increased from about 9% to about 15%.

Q: What appears to be driving this trend?

A: This is something we do not yet know. First, we want to look at other databases and institutions and see what is similar across the board. We want to confirm that this is not an artifact of the data. Then we need to look at other factors, such as environmental factors. With our data, we looked to see if maybe the increase had to do with earlier diagnoses, because we now have fancier imaging, but this did not appear to be the case. We also looked at race/ethnicity, which serves as a surrogate for mutational patterns that often are seen in never-smoker lung cancer cases. There are targeted therapies for some of these mutations, and there are some institutions that are conducting clinical trials of these targeted therapies. Obviously, they attract a higher percentage of patients with these specific mutations for that reason. In our study, we did not see that race/ethnicity made any difference in the rates. The increase that we are seeing appears to be independent of race and ethnicity, and it also appears to be independent of stage.

Q: In your opinion, what can be done about it?

A: If this turns out to be confirmed, the next step ― once we find out what is causing this increase ― is to find a way to change what we do in terms of screening. But at this point, the data are still early, so we are not proposing any changes in screening among low-risk patients such as never-smokers. At this point, it would be too premature to make guidelines for screening lower-risk populations. The data are definitely out that screening in higher-risk populations can help improve survival. In the lower-risk populations, though, it is still too early. However, it is important for everyone to keep in mind that lung cancer can occur among never-smokers.

Q: Do treatment options for never-smokers with lung cancer differ from those with lung cancer who have smoked?

A: Some of the treatment options are definitely the same, but lung cancer in never-smokers is more likely to have “targetable” mutations that confer sensitivity to certain targeted oral chemotherapy agents, as well.

Q: Is there a certain population of nonsmokers that appear to be affected more so than others?

A: The typical demographic is never 100%, but often times we see it more so in females.

Q: Are the rates higher in one geographic area than others?

A: Our data only looked at two areas in the United States, though they were demographically diverse. However, another study published by a group in the United Kingdom ― led by Eric Lim, MB, ChB, MD, MSc, FRCS (C-Th) ― showed a similar trend as we did. Asia has a higher rate of never-smokers with lung cancer. It is estimated that about 50% of Asian females with lung cancer are never-smokers.

Q: Do you have anything else you would like to add?

A: We are hoping to get these data out, and hopefully the data will bring about good questions. More research and a closer look at these data need to occur. Then, I think we will have a better idea of what is causing this trend, and we can figure out what we can do about it. – by Jennifer Southall

Reference:

Pelosof L, et al. Abstract ORAL22.01. Presented at: 16th World Conference on Lung Cancer; Sept. 6-9, 2015; Denver, Colorado.

Proli C. Abstract ORAL24.03. Presented at: 16th World Conference on Lung Cancer; Sept. 6-9, 2015; Denver, Colorado.

For more information:

Since the conduct of this research, Lorraine Pelosof, MD, joined the FDA as medical officer for the Center for Drug Evaluation and Research’s Office of New Drugs and Office of Hematology and Oncology Products. She can be reached at: lorraine.pelosof@fda.hhs.gov.

Disclosure: Pelosof reports no relevant financial disclosures.