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, geographical and socioeconomic differences and past epidemiological 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 socio-economic 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.