Section 5. Breast: Overview: Current status of breast conserving therapy in Japan

Breast conserving operations have become the standard operation for early breast cancer. They were performed in about 40% of all breast cancer patients in Japan in 2000, and the percentage is still increasing. Ductal carcinoma in situ (DCIS) accounts for about 7% of all breast cancers and breast conserving operations for DCIS have been followed by a low in-breast recurrence rate, leading to wider indications for breast conserving operations as screening mammography has come to be used in Japan. In-breast recurrence is correlated to surgical margin status. It is important to evaluate the surgical margin for volume of cancer cell nests as well as for positivity. Neoadjuvant chemotherapy has become popular as an in vivo sensitivity test and as a means of down-staging to increase the possibility of performing a breast conserving operation. There are two patterns of shrinkage when neoadjuvant chemotherapy is effective: cocentric and honeycomb, and the pattern of residual cancer cell nests must be determined before surgery. MRI is an effective method of evaluating residual cancer cell nests. The in-breast recurrence rate after down-staging to perform breast conserving operations is reported to be higher than among candidates for breast conserving operation at the start. Sentinel node biopsy techniques and endoscopic operations are now being assessed in conjunction with breast conserving operations. The current status of breast conserving operations in Japan is reviewed in comparison with their status in Western countries.