Analysis of Local Recurrence Risk in Ductal Carcinoma In Situ and External Validation of the Memorial Sloan Kettering Cancer Center Nomogram

SIMPLE SUMMARY: Adjuvant treatments after breast-conserving surgery (BCS) in ductal carcinoma in situ (DCIS) have shown to reduce the risk of ipsilateral breast tumor relapse (IBTR), but its effect on overall survival remains controversial. Due to this argument, some nomograms tried to select the patients who may benefit the most to these not free of side-effects adjuvant treatments. In this study, an external validation of the Memorial Sloan Kettering Cancer Center (MSKCC) nomogram was performed not reaching statistical significance in a Spanish cohort of patients. Nonetheless, the expression of estrogen receptors, not included in the MSKCC nomogram, showed potential prediction power for IBTR in the studied population and may be considered in future nomograms. ABSTRACT: Background: Adjuvant radiotherapy and hormonotherapy after breast-conserving surgery (BCS) in ductal carcinoma in situ (DCIS) have been shown to reduce the risk of local recurrence. To predict the risk of ipsilateral breast tumor relapse (IBTR) after BCS, the Memorial Sloan Kettering Cancer Center (MSKCC) developed a nomogram to analyze local recurrence (LR) risk in our cohort and to assess its external validation. Methods: A historical cohort study using data from 296 patients treated for DCIS at the Hospital Clínic of Barcelona was carried out. Patients who had had a mastectomy were excluded from the analysis. Results: The mean age was 58 years (42–75), and the median follow-up time was 10.64 years. The overall local relapse rate was 13.04% (27 patients) during the study period. Actuarial 5- and 10-year IBTR rates were 5.8 and 12.9%, respectively. The external validation of the MSKCC nomogram was performed using a multivariate logistic regression analysis on a total of 207 patients, which did not reach statistical significance in the studied population for predicting LR (p = 0.10). The expression of estrogen receptors was significantly associated with a decreased risk of LR (OR: 0.25; p = 0.004). Conclusions: In our series, the LR rate was 13.4%, which was in accordance with the published series. The MSKCC nomogram did not accurately predict the IBTR in this Spanish cohort of patients treated for DCIS (p = 0.10).