The effect of neoadjuvant chemotherapy on ductal carcinoma in situ in triple-negative breast cancer patients: A nationwide analysis.

PURPOSE: Recent studies show that ductal carcinoma in situ (DCIS) accompanying HER2+ breast cancer can be completely eradicated following neoadjuvant systemic therapy in up to 52 %. We aimed to determine the complete response rate of DCIS in triple-negative breast cancer (TNBC) patients in a nationwide cohort and to assess clinicopathological variables associated with response. Furthermore, the impact on surgical treatment after neoadjuvant chemotherapy (NACT) was investigated.

METHODS

Women diagnosed with TNBC, treated with NACT followed by surgery, between 2010 and 2020, were selected from the Netherlands Cancer Registry (NCR). Pre-NACT and postoperative pathology reports were obtained from Palga, the Dutch nationwide pathology databank, to determine presence of DCIS. Clinicopathological factors associated with DCIS response were investigated using uni- and multivariable logistic regression analysis.

RESULTS

In total, 4494 patients were included. A DCIS component was present in the pre-NACT biopsy of 442 (9.8 %) patients. Pathologic complete response of the DCIS component was achieved in 53.6 % of these patients. The presence of calcifications in the pre-NACT biopsy was associated with a lower chance of DCIS response in univariable logistic regression analysis (OR 0.52, CI 95 % 0.27-0.98, p = 0.04). In multivariable analysis, no statistically significant associations were found between DCIS response and clinicopathological variables. Mastectomy rates were higher in case of IBC + DCIS compared to IBC (53.4 % vs 40.1 %, p < 0.001).

CONCLUSION

Pathologic complete response of DCIS to NACT occurred in 53.6 % of TNBC patients. Future studies are required to be able to predict DCIS response based on clinicopathological variables and imaging.