Incidence of inflammatory breast cancer in women, 1992-2009, United States.

ABSTRACT

BACKGROUND: The annual incidence of inflammatory breast cancer (IBC) in the United States reportedly increased during the last quarter of the twentieth century. We investigated whether that increase has continued into the twenty-first century. METHODS: We queried the Surveillance Epidemiology and End Results database for all cases of IBC in women age 20 and older between 1992 and 2009. Cases were breast tumors with at least one of the following codes extent of disease size 998, extension 70, or ICD-3-O morphology 8530 or 8533. Age-adjusted incidence was also examined. RESULTS: During 1992-2009, the annual incidence of IBC did not increase over time in any age group, nor did it vary significantly from year to year, except between 2003 and 2004, when there was a jump from 1.6 (95 % confidence interval 1.4-1.8) to 3.1 (2.8-3.4) cases per 100,000 women. Similar changes occurred in all age and racial groups before gradually returning to prejump levels. Overall, the incidence of IBC rose steeply with age until reaching a plateau at age 65. The incidence was greatest among black women (3.0; 2.8-3.2), intermediate among white women (2.1; 2.1-2.2), and lowest among Asian women (1.4; 1.3-1.6). CONCLUSIONS: The incidence of IBC has remained essentially stable for nearly two decades. A transient jump in 2003-2004 occurred in all age and racial groups, suggesting adjustment to coding changes at that time. Often described as a disease of younger women, IBC in fact disproportionately affects older women. Racial/ethnic variation in the incidence of IBC suggests that dietary, lifestyle, or genetic factors contribute to its pathogenesis.