Abstract P3-07-06: Initial treatment and survival among elderly breast cancer patients with positive estrogen receptor status by progesterone receptor status and stage: an analysis of US national registry data 2000–2009

Abstract

Abstract BACKGROUND: There are few recent studies of initial treatment and survival among elderly, newly diagnosed breast cancer (BC) patients with positive estrogen receptor (ER) status, by progesterone receptor (PR) status and cancer stage at diagnosis. METHODS: The linked Surveillance and Epidemiology End Results-Medicare (SEER-Medicare) database was used for this analysis. SEER is an epidemiologic surveillance system consisting of population-based tumor registries designed to track cancer incidence and survival in geographically defined areas that represent approximately 25% of the US population. The SEER registry file (available through 2007) is linked to Medicare claims and enrollment data available through 2009. We identified female patients newly diagnosed with ER positive (ER assay reported to SEER as positive/elevated) Stage I, II, III, or IV breast cancer in a SEER registry between January 2002 and December 2007. Study patients were required to be aged 66+ years with no prior history of any other (non-breast) cancer. Patients were followed from the date of breast cancer diagnosis through death or December 31, 2009. PR status was collected in the breast cancer site-specific factor variable, with patients identified as PR+ (PR−) if the PR assay was reported to SEER as positive/elevated (negative/normal). Demographics, initial treatment (surgery or radiation within 4 months of diagnosis), and survival (proportion of patients who died during the study period, survival at 96 months and median survival) were evaluated, by PR status and cancer stage. Kaplan-Meier (KM) survival curves were estimated by PR status and stage. RESULTS: 57,571 female ER+ BC patients (47,385 PR+, and 10,186 PR−) were identified. Age at diagnosis was similar for PR+ and PR- BC patients (mean [SD] 75–77 [7]; median 75–77 years) across all stages. Compared to PR- patients, those with PR+ status were more likely to be diagnosed at Stage I (56.6% vs. 50.7%), and slightly less likely to be diagnosed at other stages (Stage II: 31.7% PR+ vs. 33.2% PR−; Stage III: 7.7% vs. 10.4%; Stage IV: 4.0% vs. 5.7%). Most patients had surgery in the first 4 months following diagnosis (96% PR+; 94% PR−), with Stage IV patients least likely (42% for both PR+ and PR−). Similar proportions of PR+ and PR- patients received initial radiation (49% vs. 46%), with minor variation across stages. Overall, fewer PR+ patients died during the evaluation period (22% vs. 28% PR−). KM survival analyses suggest that survival rates were higher for PR+ than PR- patients overall (survival at 96 months: 64% vs. 59%), and, with the exception of Stage I (73% for both), by stage (Stage II: 61% vs. 55%; Stage III: 40% [median survival 76 months] vs. 31% [median 58 months]; Stage IV: 14% [median 25 months] vs. 9% [median 19 months]). CONCLUSIONS: Among elderly, newly diagnosed ER+ BC patients, those with PR+ status were diagnosed at earlier stages and had better survival outcomes. Further studies of treatment patterns and outcomes in the ER+ BC population are warranted. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P3-07-06.