Gender and lung cancer-SEER-based analysis

Abstract

Background: Lung cancer remains a major cause of death worldwide. While in the past it was considered to primarily afflict males, in recent decades the number of female patients has risen, such that rates among females are similar to those among males. Nevertheless, it has been found previously (e.g., in cardiovascular disease) that when there is a sex-specific stereotype to a disease, it may remain entrenched in medical diagnostic processes, so as to cause belated diagnosis among the other sex. Gender-based differences in incidence and diagnosis are likely to exist with respect to lung cancer because of smoking habits and stereotypes, geographic and socioeconomic differences, and past epidemiologic differences between the sexes. Here we aim to characterize the effects of gender on lung cancer diagnosis and whether such effects have changed over time.

Methods: The SEER (Statistics, Epidemiology, and End Results) database was used to check for sex-based differences by tumor type and stage at diagnosis and to investigate whether these patterns have changed with time by comparing staging data in different age cohorts over time. Results were stratified by location and analyzed with data regarding possible confounders such as smoking and socioeconomic factors.

Results: We examined 458,132 cases of lung cancer from the years 2004-2012; 243,021 (53%) in males and 215,111 (47%) in females. Lung cancer rates were 73.8 (73.5-74.1) per 100k in males and 51.6 (51.4-51.8) per 100k in females. Of these, 400,800 had the stage listed, 214,479 (54%) in males, and 186,321 (46%) in females. Total lung cancer rates were higher in males than females at all disease stages. Male patients were more likely than female patients to be diagnosed at stage 3-4, consistent across lung cancer types, cancer registries, smoking, and socioeconomic backgrounds. The difference between the percentage of males versus females diagnosed in stages 3-4 correlated negatively with increased female ever-smokers and with squamous and small cell carcinoma and were not correlated with the rate of cancer in females, or the difference between male and female cancer rates.

Conclusions: Our study showed that there is no belated diagnosis of lung cancer in females. Results appear to point to the fact that smoking females are more likely to be diagnosed at later stages, which is consistent with the current literature.

Keywords: Gender; Late diagnosis; Lung cancer; SEER database; Screening; Sex.