Trends in synchronous invasive ductal carcinomas of the breast: A SEER database analysis.

Abstract

e13081 Background: Synchronous breast cancers are uncommon and account for around 2% of all breast cancer diagnosis. Lobular histology is considered a risk factor for synchronous breast cancers. We sought to study the trends in synchronous breast cancer of ductal histology and influence of age by interrogating the SEER database. Methods: The SEER Research data 1973-2013 was interrogated for synchronous infiltrating ductal carcinoma diagnosis (2 diagnosis within 6 months of each other). Overall survival (OS), the primary endpoint, was defined as the time (in months) from diagnosis to death from any cause. Univariate proportional hazards modeling results were used to assess the effect of age, race and stage on overall survival. All associations were considered statistically significant at an alpha error < 0.01. All analyses were performed using SAS version 9.4. Results: 1469 cases were identified. Data was categorized by age group: ≤ 65 years or > 65 years. 60% were 65 years or younger. 85% were Caucasians, 9.6% African Americans and 5.2% others. Younger women (≤ 65 years) had a statistically higher proportion of Stage III/IV breast cancer diagnosis as compared to older women (33.4% vs 25.2%; p = 0.002). The incidence rate of synchronous breast cancers has been rising since 1973, more pronounced in the older age group. Incidence rates overall have risen from 0.09/100,000 persons in 1973-1980 to 0.29/100,000 persons in 2001-2013 (p < 0.001). Incidence rates for synchronous breast cancer in women > 65 years has increased from 0.30/100,000 persons in 1973-1980 to 1.03/100,000 persons in 2001-2013. The adjusted OS among older women is significantly worse than that of younger women (HR 1.05; 95% CI 1.04-1.05; p < 0.001). Conclusions: Better imaging techniques and breast cancer screening guidelines have likely improved breast cancer detection rates thus leading to a rise in the incidence of synchronous breast cancers. It can be speculated that underlying medical problems and advanced age result in more morbidity and subsequent mortality in older women with standard treatment. The finding of more advanced disease among younger women deserves scrutiny as to cause.