| Purpose. To compare mammographically occult (MamOcc) and mammographically positive (MamPos) early-stage breast cancer patients treated with breast-conservation therapy (BCT), to analyze differences between the two cohorts.;Methods. The 2 cohorts were comprised of 214 MamOcc and 2168 MamPos patients treated with BCT. Chart reviews were conducted to assess mammogram reports and method of detection. All clinical--pathologic and outcome parameters were analyzed to detect differences between the two cohorts.;Results. Median follow-up was 7 years. There were no differences in final margins, T stage, nodal status, estrogen/progesterone receptor status, or "triple-negative" status. Significant differences included age at diagnosis (p < 0.0001), more positive family history (p = 0.0033), less HER-2+ disease (p = 0.0294), and 1° histology (p < 0.0001). At 10 years, the differences in overall survival, cause-specific survival, and distant relapse between the two groups did not differ significantly. The MamOcc cohort had more breast relapses (15% vs. 8%; p = 0.0357), but on multivariate analysis this difference was not significant (hazard ratio 1.0, 95% confidence interval 0.993--1.007, p = 0.9296). Breast relapses were more commonly not picked up on mammography in the MamOcc cohort (32% 12% p = 0.0136).;Conclusions. Our study suggests that there are clinical--pathologic variations for the MamOcc cohort vs. MamPos patients that may potentially affect management, but that breast relapse rates after BCT are ultimately not significantly different for these 2 cohorts. Breast recurrences were more often mammographically occult in the MamOcc cohort; consideration should be given to closer follow-up and alternative imaging strategies (ultrasound, breast MRI) for routine post-treatment examination. To our knowledge, this represents the largest series addressing the prognostic significance of MamOcc cancers treated with BCT. |
