An epidemiologic study of early onset lung cancer.

Using cases from an ongoing case-control study, we completed a case series analysis by comparing epidemiologic, clinical and survival characteristics among lung cancer patients characterized by age at diagnosis. Our sample included 230 early onset lung cancer (EOLC) (all Caucasian and no older than 50 years of age at diagnosis) and 426 later-onset cases (LOLC) (all Caucasian and no younger than 70 years of age at diagnosis) who were referred to The University of Texas M.D. Anderson Cancer Center, Houston between 1995 and 2004. Detailed lifestyle, exposure, clinical, survival and self-reported cancer family history data were available from personal interviews. We observed a higher proportion of never smokers (23.9%) for the EOLC cases as compared to the LOLC cases (17.6%) and a higher proportion of former smokers (59.4%) among the LOLC cases compared to EOLC cases (17.8%). Adenocarcinoma was the most common histology (55.2%) among the EOLC cases. More (83.4%) of the EOLC cases presented with stage 3 or 4 lung cancer compared to the LOLC cases (58.6%). Median (M) survival was 16.7 months among the EOLC cases (M = 19.2 months for the LOLC cases) and the 24-month survival rate was 20.6% for the EOLC cases and 29.5% for the LOLC cases. Female EOLC cases (M = 20.7 months) exhibited better survival than male EOLC cases (M = 13.0 months, P = 0.004). EOLC cases diagnosed with squamous cell carcinoma had poorer survival (M = 8.2 months) compared to cases with other histologies (P < 0.001). For both groups, higher stage at presentation was associated with poorer survival (P < 0.001). These findings support the need for further study in the characterization and identification of genetic factors that influence and modulate early onset lung cancer risk and outcome.