Geographical differences in primary therapy for early-stage breast cancer

Breast-conserving surgery may not be uniformly available to all women. We evaluated geographical differences across Connecticut in the proportions of cases with early stage breast cancer treated by partial mastectomy (PM). We also looked at geographical variation in PM with axillary lymph node dissection (AND) and PM with adjuvant radiotherapy (RAD).

The Connecticut Tumor Registry identified 9106 cases of early disease for 1991 to 1995. Latitude-longitude coordinates for place of residence at diagnosis and initial form of therapy were available for 8795 records. A spatial scan statistic was used to detect geographical differences in treatment rates across the state.

A total of 57.7% of early breast cancer cases were treated by PM. Women living around New Haven were less likely than others to be treated in that manner (relative risk [RR] = .86; P = .0001), whereas those living around Norwalk were more likely (RR = 1.26; P = .0001). PM with AND, relative to PM alone, was reported less often for cases from a large area of southwestern Connecticut (RR = .89; P = .0001), but more often for those in north central Connecticut (RR = 1.13; P = .0001). PM with RAD, relative to PM alone, was less common for cases around Danbury (RR = .40; P = .0001) but more common among cases around Hartford (RR = 1.14; P = .0001).

Geographical analysis is a way for physicians and health officials to identify groups of women who may not yet benefit from preferred surgical procedures.