Introduction:
Breast cancer (BC) is the most commonly diagnosed cancer among women in the United States, but less than 5% of women develop BC before age 40. We sought to determine the trend over time in incidence and survival rates, and pathologic features of Non-Hispanic White (W), Non-Hispanic Black (B) and Hispanic (HIS) women (<40 years) with invasive breast cancer.
Methods:
Women <40 years old diagnosed with invasive BC were identified from the SEER 13 registry. Patients were stratified by year of diagnosis (1992-2014), race/ethnicity (W, B, and HIS) and pathologic features (stage, grade, ER and PR status). Age-adjusted incidence rates and 5- and 10-year disease-specific survival (DSS) rates were calculated. Incidence rate ratios (IRRs) were estimated by race/ethnicity group and pathologic features to express relative risk of BC incidence. Temporal trends of incidence rates (1992-2014), 5- (1992-2009) and 10-year (1992-2004) DSS rates were assessed as average annual percentage change (AAPC) using a joinpoint model. Survival estimates were calculated using the Kaplan-Meier method and Log-rank tests were used to test for differences in DSS among the race/ethnicity groups.
Results:
A total of 28,686 patients were included in this analysis: 64.1% W, 16.6% B, and 19.3% HIS. Overall, young B women had a higher incidence and worse survival than W women. Tumors with poor prognostic features (stage IV, grade III, ER- and PR-) were more common than those with better prognosis (stage 1, grade 1, ER+ and PR+, respectively) among young B women compared to W and HIS women. Young B women had worse 5- and 10-year DSS compared to their W and HIS counterparts (all p<0.001).
Young W women experienced a 0.8% per year increase in the incidence of invasive BC; incidence rates were stable in B and HIS women. B women had a slightly higher AAPC than W women for 5- and 10-year DSS rates. The incidence of advanced stage tumors (stage 4) and PR- tumors has been rising slightly faster in B than W women.
Trends of incidence and mortality rates by race/ethnicity and pathologic features. WBHISIRR (95% CI)Overall vs HIS1.38 (1.34-1.42)1.74 (1.69-1.81)referenceStage 4 vs 10.13 (0.12-0.14)0.41 (0.36-0.46)0.26(0.23-0.30)Grade 3 vs 17.43 (7.02-7.89)13.82 (11.99-16.00)10.40 (9.22-11.76)ER- vs +0.55 (0.53-0.56)0.83 (0.78-0.88)0.64 (0.60-0.66)PR- vs +0.71 (0.69-0.73)1.13 (1.06-1.20)0.85 (0.80-0.91)DSS 5-yr86.7 (86.1-87.2)72.9 (71.5-74.3)80.6 (79.4-81.8)10-yr78.0 (77.3-78.7)63.2 (61.5-64.8)71.4 (69.9-72.9)AAPCOverall0.8*0.20.2Stage 44.3*4.4*3.0*Grade 31.4*1.11.0*ER--0.4-0.50.2PR-1.1*1.2*1.9*DSS 5-yr0.6*0.8*0.8*10-yr0.9*1.0*1.1**AAPC is statistically different from zero (p<0.05).
.
Conclusion:
The incidence of higher stage and PR- tumors is increasing at a faster rate in young black women when compared to whites. Although the incidence of BC is increasing over time for young white women and not young black women, disparities still exist in overall incidence. Similarly, although DSS is increasing at higher rates for black and Hispanic women compared to whites, large survival disparities still exist. Improvements have been made over time, but more work needs to be done to determine which factors are associated with these disparities and how to close the gap in survival.
Citation Format: Oyekunle TO, Thomas SM, Greenup RA, Hyslop T, Blackwell K. Incidence and mortality among breast cancer patients < 40 years old: U.S. trends from 1992-2014 [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P6-10-01.
