Abstract PS7-06: Incidence and survival of inflammatory breast cancer between 1973 - 2015 in the surveillance, epidemiology and end results (SEER) database
Authors: Abraham Hannah , Xia Yaoxuan , Mukherjee Bhramar , Merajver Sofia D 
Published: February 2021

PurposeInflammatory breast cancer (IBC) is a rare and aggressive variant of breast cancer characterized by erythema, edema, and “peau d’orange” of the breast progressing within six months. We assessed the incidence and survival of IBC in the US currently, compared to historical results.

MethodsUsing SEER*Stat, a case list of IBC patients diagnosed between 1973-2015 (n = 29,718) was extracted from the SEER 18 registries by defining IBC using a combination of morphology, stage, and extent of disease criteria. Age-adjusted incidence rates, relative survival rates, and mean survival time were calculated. Significance was determined as non-overlapping 95% confidence intervals.

ResultsThe overall incidence of IBC from 1973 - 2015 is 2.76 (2.73, 2.79) cases per 100,000 people, with white patients having an incidence rate of 2.63 (2.60, 2.67), black patients 4.52 (4.39, 4.65), and patients of other race 1.84 (1.76, 1.93). The relative rate of 5-year survival for IBC patients as a whole is 40.5% (39.0%, 42.0%), with white patients having a rate of 42.5% (40.7%, 44.3%) and black patients’ survival rate 29.9% (26.6%, 33.3%) (see Table 1). White patients diagnosed in 1988-1992 have a mean survival time of 81.9 (53.5, 110.3) months, while those diagnosed in 2008-2012 have mean survival time of 101.9 (90.0, 113.7) months. In contrast black patients diagnosed in 1988-1992 have a mean survival time of 48.5 (37.5, 59.4) months, while those diagnosed in 2008-2012 have mean survival time of 84.3 (77.2, 91.4) months (see Table 2).

ConclusionsOur results suggest that IBC survival has moderately increased in recent years. However, despite the overall improvement in survival for all racial groups, there remains a persistent survival disparity between white and black patients that has not narrowed over two decades. Further research is urgently needed to understand and address this disparity.

Table 1: Relative Survival Rates for inflammatory breast cancer by race, %(95% CI). “Cohort”: cohort analysis, “Period”: period analysis.5-year10-year15-year20-yearBlackCohort29.8 (26.7, 32.9)14.8 (10.9, 19.4)10.4 (5.0, 18.1)3.7 (0.7, 11.2)Period29.9 (26.6, 33.3)18.4 (15.2, 21.8)16.7 (12.9, 20.9)16.2 (9.1, 25.1)WhiteCohort44.0* (42.4, 45.7)30.6* (28.2, 33.0)22.1* (18.8, 25.6)17.5* (13.4, 22.0)Period42.5+ (40.7, 44.3)30.7+ (28.9, 32.5)25.1+ (22.7, 27.5)22.1 (19.2, 25.2)OtherCohort46.8* (41.5, 51.8)26.3 (18.5, 34.7)19.1 (10.3, 29.9)14.1 (3.8, 31.0)Period43.6+ (38.0, 49 .0)32.6+ (26.7, 38.7)30.5 (22.8, 38.6)26.9 (18.3, 36.3)AllCohort41.9* (40.5, 43.3)28.0* (25.9, 30.0)21.3* (18.3, 24.4)15.6* (12.1, 19.5)Period40.5+ (39.0, 42.0)28.9+ (27.4, 30.4)24.0+ (22.0, 26.1)21.5 (18.9, 24.2)Significance relative to black patients, determined by non-overlapping 95% CI calculated via the Greenwood method and demonstrated by * for cohort and + for period analysis.

Table 2: Mean Survival Months by Race Before and After Imputation Using Cox Model Adjusted for Age and Race (95% CI).Mean Survival Time (Months)African AmericanWhiteYearUnadjustedAdjustedUnadjustedAdjusted1988-199246.4* (37.4, 55.4)48.5 (37.5, 59.4)71.3 (65.9, 76.7)81.9 (53.5, 110.3)1993-199649.1* (41.8, 56.4)61.0 (48.2, 73.8)68.1 (64.6, 71.6)86.1 (59.0, 113.2)1997-200247.4* (43.7, 51.2)63.8* (55.3, 72.3)64.8 (62.9, 66.7)99.8 (81.0, 118.7)2003-200741.0* (39.5, 42.5)72.1* (66.6, 77.7)49.9 (49.1, 50.6)98.2 (86.8, 109.6)2008-201225.7* (24.8, 26.4)84.3 (77.2, 91.4)28.7 (28.2, 29.1)101.9 (90.0, 113.7)Significance relative to white patients, determined by non-overlapping 95% CI and demonstrated by *.

Citation Format: Hannah Abraham, Yaoxuan Xia, Bhramar Mukherjee, Sofia D Merajver. Incidence and survival of inflammatory breast cancer between 1973 - 2015 in the surveillance, epidemiology and end results (SEER) database [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS7-06.