Inflammatory breast carcinoma and noninflammatory locally advanced breast carcinoma: distinct clinicopathologic entities?

PURPOSE: Inflammatory breast carcinoma (IBC) and noninflammatory locally advanced breast carcinoma (LABC) are both associated with poor prognosis; however, whether they are distinct clinicopathologic entities remains controversial.
MATERIALS AND METHODS: To determine whether IBC and LABC were different, we compared tumor characteristics, prognosis, and age-specific incidence rate patterns in the Surveillance, Epidemiology, and End-Results program. An age of 50 years served as a surrogate marker for menopause.
RESULTS: Younger age at diagnosis, poorer tumor grade, and negative estrogen receptors (ERs) were more predictive of IBC (n = 2,237) than of LABC (n = 7,985). Breast carcinoma survival was worse for patients with IBC than for those with LABC (log-rank test, P <.0001). Age-specific incidence rates for IBC increased until 50 years and then flattened, whereas rates for LABC increased for all ages. When rates for LABC were stratified by estrogen receptor-positive (ERP) and -negative (ERN) expression, rates for ERP and ERN diverged; that is, rates for ERP increased with advancing age, whereas rates for ERN flattened after 50 years. When rates for IBC were stratified by ER expression, rates for both ERP and ERN flattened after 50 years of age.
CONCLUSION: IBC and LABC seemed to be distinct biologic entities, as indicated by different prognostic factor profiles and age-specific incidence rate patterns. Rates that increased before 50 years and then stabilized, possibly indicated that premenopausal exposures had a greater effect on maintaining rates for IBC than for LABC.