Incidence and survival of inflammatory breast cancer between 1973 and 2015 in the SEER database

Inflammatory breast cancer (IBC) is an aggressive variant characterized by erythema, edema, and "peau d'orange" of the skin progressing within 6 months. We assessed the incidence and survival of IBC in the US over four decades.

Using SEER*Stat, a case list of IBC patients diagnosed between 1973 and 2015 (n = 29,718) was extracted from SEER 18 registries by using a combination of morphology, stage, and extent of disease criteria. M1 and M0 patients were included. Age-adjusted incidence rates, relative survival rates, and mean survival time were calculated. Significance was determined as non-overlapping 95% confidence intervals.

The overall incidence of IBC from 1973 to 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 overall IBC relative 5-year survival rate is 40.5% (39.0%, 42.0%), 42.5% (40.7%, 44.3%), and 29.9% (26.6%, 33.3%) for white patients and black patients, respectively. Patients diagnosed in 1978-1982 have a mean survival time of 62.3 (52.0, 72.6) months, while those diagnosed in 2008-2012 have mean survival time of 99.4 (96.4, 102.4) months. There is no significant difference in survival time between T4D patients and patients with other T staging and extent of disease coding consistent with clinical IBC presentation.

IBC survival has increased over four decades. Despite the improvement in survival for all racial groups, a persistent survival disparity that has not narrowed over two decades remains between white and black patients.