Neoadjuvant chemoradiotherapy for potentially resectable esophageal squamous cell carcinoma and the significance of Rad51 expression as a factor predictive of the treatment response.

e14601 Background: The clinical significance of neoadjuvant chemoradiotherapy (NACRT) for potentially resectable esophageal squamous cell carcinoma (ESCC) and its effect on the development of postoperative complications are unclear. On the other hand, the Rad51 expression is related to the sensitivity to chemotherapy or radiotherapy; however, the significance of the Rad51 expression in ESCC has not yet been clarified. Methods: 1) One hundred sixty-eight patients with clinical Stage II-III (cStageII-III) ESCC were classified into two groups consisting of 76 who received NACRT followed by esophagectomy and 92 patients who received surgery alone. The prognosis and incidence of postoperative complications were retrospectively compared between the two groups. The pathological response to NACRT as well as the patient prognosis were also analyzed for the NACRT group patients. 2) The expression of Rad51 was investigated in pretreatment biopsy specimens in 41 ESCC cases who underwent surgery after NACRT, and the findings were compared with the pathological response to NACRT. Results: 1) The 5-year survival rate was 47.7% in the surgery alone group and 56.5% in the NACRT group, and the difference was not a statistically significant (p=0.4831). However, the 5-year survival rates of patients in whom NACRT was Grade 3 (markedly effective), was obviously better than that of the other patients (Grade0/1 – ineffective/slightly effective: 36.9%, Grade 2 - moderately effective: 53.8%, Grade 3 - markedly effective: 100%). The incidence of postoperative complications was 31.5% in the surgery alone group and 40.8% in the NACRT group, and the difference was not a statistically significant (p=0.2121). 2) Grade 3 was more frequently observed in Rad51-negative cases (n=13) than Rad51-positive cases (n=28; 71.4% vs. 28.6%, p=0.0239). Conclusions: The pathological complete response of NACRT is critical for improving the survival of patients with cStageII-III ESCC. The Rad51 expression in pretreatment biopsy specimens was therefore suggested to be a useful predictive factor for the response to NACRT.