Inflammatory and other breast cancer incidence rate trends by estrogen receptor status in the Surveillance, Epidemiology, and End Results database (2001-2015).

Our results show a reversal of the rising rates of IBC overall reported at the end of the twentieth century. Direction of trends for IBC is consistent with other breast cancer types, except for ER+ localized breast cancer in older women. Decreasing parity and rising prevalence of older age at first birth may contribute to declining rates of ER- IBC. Otherwise, patterns of changing risk factors are inconsistent with the trends we observed. Further studies of IBC are necessary to identify additional risk factors and possible preventive strategies.