OBJECTIVE: To explore whether Paget's disease (PD) has an effect on outcome in patients with breast cancer.

DESIGN: Retrospective analysis of comprehensive pathology database, medical records, and slides of samples showing pathologic features.

SETTING: UMass Memorial Health Care.

PATIENTS: All patients with breast cancer and PD with records in a prospectively maintained database between January 1, 1990, and December 31, 2008, were identified. Each participant was matched (criteria: age within 5 years, year of treatment, and stage of breast cancer) with 2 controls (1:2 ratio).

MAIN OUTCOME MEASURES: Overall and disease-free survival were analyzed using Kaplan-Meier statistics and Cox proportional hazards modeling, accounting for matching in the latter analyses by using robust standard error estimates.

RESULTS: Mean (SD) follow-up was 47 (33) months. Treatment involved mastectomy in 29 (91%) PD vs 16 (25%) non-PD patients (P < .001), radiotherapy in 14 (44%) PD vs 53 (83%) non-PD patients (P < .001), and hormonal therapy in 14 (44%) PD vs 33 (52%) non-PD patients (P = .004). Biological markers were not significantly different except for ERBB2 (formerly HER2 or HER2/neu) overexpression in 14 (44%) PD vs 16 (25%) non-PD patients (P = .008). The PD group had an overall 5-year survival of 81.2% vs 93.8% of the non-PD group (Kaplan-Meier log-rank, P = .03). The unadjusted hazard ratio for the PD vs non-PD group was 5.31 (95% CI, 1.74-16.27; P = .003). The corresponding hazard ratio after adjusting for local and systemic treatment was 2.26 (95% CI, 0.46-11.06; P = .32).

CONCLUSIONS: These exploratory data show that PD may have a negative effect on breast cancer survival. This finding needs to be substantiated in larger data sets.