Impact of estrogen monotherapy on survival in women with stage III-IV non-small cell lung cancer

Abstract

ObjectivesWomen with lung cancer have better survival than men. The reasons are unknown, but estrogen is hypothesized to improve survival. Our objective was to examine the association between estrogen monotherapy and cancer-specific and overall survival in elderly women with non-small cell lung cancer (NSCLC). Materials and methodsWe used the SEER-Medicare database to identify women ≥65 years old who were diagnosed with stage III or IV NSCLC. Estrogen monotherapy (EM) was defined as at least one estrogen claim without any progesterone claims 6 months prior to diagnosis. To assess cancer-specific survival and overall survival, we used Kaplan-Meier and multivariate Cox modeling with propensity score adjustments. As an exploratory analysis, we also examined the effect of combined estrogen and progesterone hormonal therapy on survival using Cox modeling. ResultsWe identified 6958 women in our initial cohort: 283 used EM (4%) and 6675 (96%) did not. The median follow-up time was 46.5 months in the EM patients and 49.5 months in the non-EM patients. In a Kaplan-Meier analysis, median overall survival was 8.2 months in patients who receive EM and 6.2 months in those who did not (p = 0.004).In our 1:4 propensity-matched cohort, median follow-up was 46.5 in the EM group and 50.6 in the non-EM group; median overall survival was 8.0 months in the EM group and 6.4 months in the non-EM group (p = 0.02). In a multivariate Cox regression of the matched cohort, EM was significantly associated with overall survival (HR 0.84; 95% CI 0.73 – 0.97). All results were similar for cancer-specific survival. In our exploratory analysis, combined Estrogen-Progesterone did significantly impact overall survival (HR 0.84; 95% CI 0.71–0.99, p = 0.04) but did not appear to effect cancer-specific survival (HR 0.91; 95% CI 0.77–1.09, p = 0.30). ConclusionEM was associated with a significant improvement in cancer-specific survival and overall survival in women with late stage NSCLC.