Investigation of factors related to periods to ipsilateral breast tumor recurrence after breast-conserving surgery and measures for preventing recurrence in early breast cancer

BACKGROUND: The most important issue in breast-conserving surgery is avoidance of ipsilateral breast tumor recurrence (IBTR). We have investigated the factors related to the period between surgery and recurrence and the measures taken. SUBJECT AND METHODS: From April 1989 to December 2004, 888 cases (excluding cases who underwent neoadjuvant chemotherapy) of breast-conserving surgery were performed. IBTR occurred in 56 of these cases. We investigated the timing of these recurrences. Furthermore, the rate of recurrence before and after 1999 when postoperative adjuvant therapy (such as CEF and Taxanes) was started as standard treatment was investigated. RESULTS: The mean period to recurrence in the 56 patients that experienced IBTR was 41.3 months; early recurrence within two years occurred in 21 (37.5%) patients. On the other hand, recurrence from the fifth year onwards post-surgery occurred in 11 patients (19.6%). Of the factors related to the timing of recurrence, a significant difference was seen in tumor proliferative activity, ER (estrogen receptor) status, lymphatic invasion (ly), and whether the lesion was inside or outside the mammary gland tissue. Furthermore, patients experiencing an early recurrence including inflammatory type breast recurrence had a complicated course with distant metastases and their prognosis was poor. Therefore, there was delayed onset of recurrence in the ER positive and ly negative patients with decreased tumor proliferation. With regard to the timing of operation in relation to adjuvant therapy, there was an increase in the conservation rate for the patients in the later phase of the study (1999 onwards), and the number of significantly large and surgical margin positive patients that were at risk of a recurrence was high. However, early recurrence was significantly low, and standard therapy was found to inhibit recurrence. CONCLUSIONS: Although tumor proliferative activity, ER status and ly caused differences in timing of recurrence, standard adjuvant therapy, particularly chemotherapy for early recurrence, was effective in inhibiting recurrence.