Incidence of NSCLC has more than doubled among nonsmokers

The incidence of non–small cell lung cancer has more than doubled among individuals who have never smoked, according to research presented at the World Conference on Lung Cancer.

Perspective from Edward S. Kim, MD

Never-smokers accounted for nearly 28% of NSCLC diagnoses in 2013, up from 13% in 2007, according to researchers. Further, many of these never-smokers presented with advanced-stage disease.

Eric Lim, MD, MSc, a thoracic surgeon at Royal Brompton & Harefield NHS Foundation Trust in London, and colleagues sought to define the incidence of NSCLC in never-smokers. In addition, researchers used data from the prospectively collected database of patients at Royal Brompton to evaluate clinical features of never-smokers who presented early with NSCLC and underwent surgery.

The analysis included data from 2,170 patients who underwent lung cancer surgery between March 2008 and Nov. 2014.

The incidence of lung cancer in never-smokers climbed steadily from 13% in 2007, to 15% in 2008, 18% in 2009, 19% in 2010, and 20% in 2011 and 2012. The incidence then jumped to about 28% in 2013.

This trend is attributable to an increase in the absolute number of never-smokers diagnosed with NSCLC and not a change in the ratio of never-smokers to ever-smokers, Lim said.

Researchers also identified a series of nonspecific symptoms that patients presented with that may make it harder to identify NSCLC without imaging. Imaging may, thus, play a more important role in diagnosing NSCLC in nonsmokers in the future, Lim said.

Fifty-two percent of the patients presented with a cough (34%) or chest infection (18%), neither of which are specific enough individually to warrant a potential NSCLC concern.

Also, 36% of the patients did not have any symptoms. Thirty percent of NSCLCs were detected on an incidental CT scan, 14% were detected on incidental chest film, 7% were detected on incident PET/CT, and 1% were detected on incidental MRI.

Meanwhile, specific symptoms that are indicative of NSCLC occurred in only 11% of the patients, with coughing blood being the most prevalent.

“Clearly it’s not going to be cost-effective to screen the entire population of nonsmokers,” Lim said during a press conference. “[But] research into early detection, ideally by noninvasive molecular screening, is urgently required to identify early lung cancer in nonsmokers.” – by Anthony SanFilippo

For more information:

Lim E, et al. Increasing incidence of non-smoking lung cancer: Presentation of patients with early disease to a tertiary institution in the UK. Presented at: 16th World Conference on Lung Cancer; Sept. 6-9, 2015; Denver, Colorado.

Disclosure: HemOnc Today was unable to obtain a list of relevant financial disclosures at the time of reporting.

Perspective

Edward S. Kim, MD

Lim and colleagues report an analysis on never-smokers, as this population has become more prominent in the treatment and assessment of lung cancer. Risk factors for lung cancer detection with CT screening center around a population of patients who are aged older than 55 years with a prior history of 30 pack-years of smoking. For patients who do not have a significant smoking history, risk factors are yet to be defined. Researchers performed a retrospective analysis involving 2,170 patients, the abstract of which was presented at WCLC 2015. The final manuscript will be important to review; however, there are some aspects to consider in this analysis. There is a description of increasing incidence of lung cancer in patients who are never-smokers (13% to 28%), many of whom were diagnosed on incidental imaging. Datasets which report smoking as a risk factor need to be interpreted with caution. Lung cancer chemoprevention studies capture very comprehensive information from patients such as smoking history (date started, date stopped, packs per day), occupational history and possible exposures (carpenters, bartender etc), and other exposure history. Data regarding passive exposure is more difficult, but this also may include whether one’s parents smoked in the household. Without this type of data, it may be difficult to accurately characterize a population of never-smokers who have risk factors for lung cancer development. These limitations in our data collection will limit our ability to identify and subsequently test a diagnostic which will improve mortality and be cost-effective.

Edward S. Kim, MD

HemOnc Today Editorial Board member

Levine Cancer Institute

Carolinas HealthCare System

Disclosures: Kim reports no relevant financial disclosures.