Prediction model for individualized precision surgery in breast cancer patients with complete response on MRI and residual calcifications on mammography after neoadjuvant chemotherapy.

Background: Identifying whether there is residual carcinoma in remaining suspicious calcifications after neoadjuvant chemotherapy (NAC) in breast cancer patients can provide crucial information for surgeons in determining the most appropriate surgical approach. Therefore, we investigated factors predicting calcifications without residual carcinoma (ypCalc_0) or with residual carcinoma (ypCalc_ca) and aimed to develop a prediction model for patients exhibiting residual suspicious calcifications on mammography but complete response on MRI after NAC.
Methods: This retrospective study included breast cancer patients undergoing NAC, showing residual suspicious mammographic calcifications but complete response on MRI between January 2019 and December 2020 (development set) and between January 2021 and December 2022 (validation set). Multivariable logistic regression analysis identified significant factors associated with ypCalc_0. The prediction model, developed using a decision tree and factors from logistic regression analysis, was validated in the validation set.
Results: The development set included 134 women (mean age, 50.6 years; 91 with ypCalc_0 and 43 with ypCalc_ca) and validation set included 146 women (mean age, 51.0 years; 108 with ypCalc_0 and 38 with ypCalc_ca). Molecular subtype (P = .0002) and high Ki-67 (P = .02) emerged as significant independent factors associated with ypCalc_0 in the development set. The prediction model, incorporating hormone receptor (HR)-/human epidermal growth factor receptor 2 (HER2)+ with high Ki-67 as ypCalc_0 predictors, and HR+/HER2- cancers or HR+/HER2+ or triple-negative (TN) cancers with low Ki-67, as ypCalc_ca predictors, achieved an area under receiver operating characteristic curve of 0.844 (95% CI 0.774-0.914) in the validation set.
Conclusion: Minimized surgery may be considered for managing residual calcifications in HR-/HER2+ with high Ki-67 cancers, while complete excision is recommended for HR+/HER2- breast cancers or for HR+/HER2+or TN breast cancers with low Ki-67.
(© 2024. The Author(s), under exclusive licence to The Japanese Breast Cancer Society.)