Final analysis of a safety and efficacy trial of preoperative sequential chemoradiation therapy for the nonsurgical treatment (NST) in early breast cancer (EBC): Japan Clinical Oncology Group Trial (JCOG0306).

Abstract

552 Background: The combination of preoperative anthracycline-containing regimen and taxane can obtain a good pathologic complete response (pCR) rate for patients (pts) with EBC. To pursue higher pCR rate with maintaining good systemic control may lead to the NST in the future. The objective of this trial is to determine whether the addition of radiation therapy (RT) to chemotherapy (CT) can surpass the pCR rate of 50% as the first step of turning the NST into reality. Methods: We conducted a safety and efficacy trial of CT (4 courses of doxorubicin and cyclophosphamide [60/600mg/m2] followed by 12 courses of weekly paclitaxel [80mg/m2]) and RT (whole breast 45Gy + boost 10Gy) sequentially as a primary therapy in pts with stage I-IIIA (5.0cm ≥ tumor size ≥ 2.0cm) breast cancer (BC). All pts received mastectomy or lumpectomy 12-16 weeks after completion of RT to maximize the effect of RT. Primary endpoint was pCR rate. pCR was assessed by the central pathological review board. Results: Between June 2004 and April 2005, 108 pts were enrolled. Median age was 50 years (range 23-69). 62% (67/108) were hormone receptor (HR) +, and 31% (34/108) had HER2+. 36% of the entire population achieved a pCR. The pCR rate was 57% in pts with HR-/HER2+, and 52% in triple-negative pts, respectively. While 7% of HR–/HER2+ pts recurred, higher incidence of recurrence (24%) was observed in triple-negative pts in follow-up of 4.5 years. The rate of breast- conserving surgery was 91% (96/106). One pt received debridement for radiation associated necrosis 3 months after lumpectomy. Other toxicities were mild to moderate. Conclusions: Preoperative sequential chemoradiation therapy did not increase the risk of operative complications and could achieve high rate of breast-conserving surgery, even though expected % pCR was not achieved. Choosing the subgroup of EBC can be necessary to realize NST in the next step. Characteristics No. of pts pCR rate No. of recurrence events HR+/HER2- 46 24% 10 (22%) HR+/HER2+ 20 40% 3 (15%) HR-/HER2- 25 52% 6 (24%) HR-/HER2+ 14 57% 1 (7%) No significant financial relationships to disclose.