Determining the morphological features of breast cancer and predicting the effects of neoadjuvant chemotherapy via diagnostic breast imaging

Background Neoadjuvant chemotherapy has recently become common therapy for breast cancer. This work studied whether or not the effects of neoadjuvant chemotherapy can be predicted from morphological features of breast cancer in initial diagnostic imaging. Materials and methods A total of 186 cases who underwent neoadjuvant chemotherapy at this hospital in 2006 were studied. Morphological features were classified into four categories. One is a type of invasive carcinoma that tends to grow along the mammary ducts (type A1), another is a type of expansively growing invasive carcinoma that is relatively well-defined (type A2), a third is a type of irregularly shaped mass that retracts surrounding tissue (type A3), and the fourth is a mixed type. Thus, the effects of neoadjuvant chemotherapy on carcinomas of the four types were compared on the basis of image and pathological findings. Effects of neoadjuvant chemotherapy were classified into three categories of enlarged mass, pCR, and other, with the latter indicating no change or shrinkage. Results Of the 186 total cases, 72 were classified as type A1, 31 as type A2, 52 as type A3, and 31 as a mixed type. Seven of 31 cases of type A2 (22.6%) were cases of an enlarged mass, revealing a high percentage of such cases. Dividing cases into type A2 and other types and looking at the proportion of cases of an enlarged mass thus indicated a significantly higher tendency. pCR was achieved in 6 of 31 cases with type A2 (19.4%). Here, also, the proportion of type A2 cases was significantly higher. Conclusion Morphological features prior to neoadjuvant chemotherapy can contribute to determining the effects of the therapy. Expansively growing well-defined masses contain lesions at both extremes, tending to enlarge in some instances or instead allowing pCR, so the course of therapy must be carefully followed when performing neoadjuvant chemotherapy. This article is based on a presentation delivered at Presidential Symposium 1, “Breast cancer: individualized diagnosis for tailored treatment,” held on 29 June 2007 at the 15th Annual Meeting of the Japanese Breast Cancer Society in Yokohama.