Breast Cancer Patients Treated With Breast-Conserving Therapy
Objective: To study whether Japanese breast cancer patients obtain favourable results with breast-conserving surgery if the same selection criteria as those for Western patients are used, and, simultaneously, to assess the outcome of breast-conserving surgery alone versus breast-conserving surgery followed by either irradiation of the remaining breast or adjuvant chemotherapy with tamoxifen.
Design and Setting: A prospective, randomised study and a retrospective study of postoperative adjuvant therapy for breast cancer following breast-conserving surgery were performed at 21 centres in Japan during 1989 to 1991.
Patients and Interventions: In the prospective, randomised study, 112 patients with tumours 2cm or smaller in diameter who underwent lumpectomy received either adjuvant chemotherapy with tamoxifen 20 mg/day for 2 years (Group T, n = 53) or no therapy (Group C, n = 59) postoperatively.
Results: Median 5-year disease-free survival rates after 72 months were 78.5% and 86.0%, respectively, with no significant difference between the two groups [log-rank test: p = 0.308, hazard ratio 1.47 (95% confidence interval 0.59-3.66)]. In the retrospective study, a further 70 patients who underwent similar breast-conserving surgery during the same period as the prospective study followed by radiotherapy (Group R) were compared with the patients in Groups T and C combined (n = 112). Median 5-year disease-free survival rates after 71 months were 86.6% and 82.2%, respectively, with no statistically significant difference between the two groups [log-rank test: p = 0.352, hazard ratio 0.72 (95% confidence interval 0.33-1.59)].
Conclusion: These findings suggest that breast cancer patients may not always require radiotherapy after breast-conserving surgery.

In Japan, breast-conserving surgery is performed in approximately 30% of all breast cancer patients, and results with this procedure have proved better than in Western patients. If tumour-negative margins of resected specimens are confirmed, postoperative radiotherapy may not be performed, and one Japanese study has reported that the prognosis after local excision of breast tumours is similar with and without postoperative radiotherapy. A high percentage of women with tumour-free margins may in fact receive unnecessary radiotherapy if breast-conserving surgery with lumpectomy plus axillary lymph node dissection plus radiotherapy is performed in all such cases. To study whether Japanese breast cancer patients obtain favourable results with breast-conserving surgery if the same selection criteria as those for Western patients are used, we initiated a prospective, randomised comparative study in 1989 and, simultaneously, a retrospective comparative study to assess the outcome of breast-conserving surgery alone versus breast-conserving surgery followed by either irradiation of the remaining breast or adjuvant chemotherapy with tamoxifen.