Abstract P2-01-02: Do decreased breast microcalcifications after neoadjuvant chemotherapy predict pathological complete response?

Abstract

Abstract Background: Clinical response evaluation by image examination after neoadjuvant chemotherapy for breast cancer is important for determining drug response and progression. Mammography is less correlated with pathological response assessment than magnetic resonance imaging or ultrasonography particularly because mammographic calcifications can increase or decrease in response to neoadjuvant chemotherapy. A conventional theory of breast microcalcifications is that they are likely to paradoxically change with neoadjuvant chemotherapy. Traditionally, microcalcifications have been said to occur due to necrosis. If conventional theory is correct, the increase in necrotic cells would increase microcalcifications in response to neoadjuvant chemotherapy. However, decreased microcalcifications were found as a clinical response to neoadjuvant chemotherapy in many cases. To increase the diagnostic ability of mammography after neoadjuvant chemotherapy, it is important to clarify the cases in which microcalcifications can be reduced by anticancer agents. The present study clarified characteristics of breast cancer cases with decreased microcalcifications after neoadjuvant. Methods: Consecutive patients who received neoadjuvant chemotherapy for breast cancer at our hospital from January 2013 to June 2017 were retrospectively reviewed. Characteristics of cases with microcalcifications before neoadjuvant chemotherapy and those showing a reduction after were examined. Stromal tumor-infiltrating lymphocytes were evaluated in the biopsy. before neoadjuvant chemotherapy based on the protocol of the International TILs Working Group 2014. Pathological complete response was also explored in cases exhibiting a decrease in microcalcifications by neoadjuvant chemotherapy. In addition, sensitivity, specificity, and likelihood ratios were calculated for pCR assessment in patients with segmental microcalcifications, pleomorphic/linear microcalcifications, and microcalcifications without mammographic mass. Results: A total of 184 breast cancer cases, including 8 with synchronous bilateral breast cancer, received neoadjuvant chemotherapy at our hospital. Of them, 114 cases were excluded due to unavailable mammograms at our institute before or after neoadjuvant chemotherapy. Seventy breast cancer cases were included; 37 had no malignant microcalcifications before neoadjuvant chemotherapy and 33 did. Breast cancer with microcalcifications was significantly more positive for human epidermal growth factor receptor 2 than those without microcalcifications (48% versus 22%, P = 0.018). Only 6 out of 33 cases with microcalcifications before neoadjuvant chemotherapy showed a decrease after treatment. These cases tended to have high stromal tumor-infiltrating lymphocytes (50% versus 17%), segmental microcalcifications (66% versus 33%), and pleomorphic/linear microcalcifications (83% versus 37%). The sensitivity of each group, compared with total cases of microcalcifications after neoadjuvant chemotherapy, tended to increase, although no significant difference was observed (sensitivity; patients with segmental microcalcifications, 42.9%; patients with pleomorphic/linear microcalcifications, 57.1%; and patients with microcalcifications but without mass, 50.0%). Conclusion: These results suggest that neoadjuvant chemotherapy is able to decrease malignant calcifications, particularly segmental and pleomorphic/linear microcalcifications and microcalcifications with high stromal tumor-infiltrating lymphocytes. By clarifying the mechanisms of formation and disappearance of microcalcifications, a consensus can be reached on whether microcalcifications apparent by mammography are useful for evaluating response to neoadjuvant chemotherapy. Citation Format: Atsushi Fushimi, Rei Kudo, Hiroshi Takeyama. Do decreased breast microcalcifications after neoadjuvant chemotherapy predict pathological complete response? [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P2-01-02.