Objective To investigate the surgical treatment strategies and prognostic factors of cT4bM0 primary rectal cancer.Methods The clinical data of 53 patients with cT4bM0 primary rectal cancer who were admitted to the First Hospital of Peking University from January 2000 to December 2010 were retrospectively analyzed.All the patients received en-bloc multivisceral resection and postoperative chemotherapy.The survival and prognostic factors were analyzed.The patients were followed up via out-patient examination,phone call or mail,and the follow-up was ended till December 2012.The survival curve was drawn using the Kaplan-Meier method,and the survival was analyzed using the Log-rank test.Uni-and multivariate analysis were done using chisquare test and COX's proportional hazard model.Results Of all the 53 patients,20 received posterior pelvic exenteration (PPE),20 received total pelvic exenteration (TPE),3 received low anterior resection (LAR) +local resection of ballder,2 received LAR + ovariectomy,2 received LAR + local resection of ureter,1 received LAR + local resection of posterior vaginal wall,1 received LAR + vesiculectomy and vesectomy,3 received abdominoperineal resection (APR) + local resection of posterior vaginal wall,1 received APR + sacrectomy.R0 resection was achieved in all the patients.No intraoperative death was observed,and the incidence of postoperative complication was 9.4% (5/53).The results of postoperative pathological examination showed that 2 patients were with well-differentiated adenocarcinoma,41 with moderate-differentiated adenocarcinoma,and 10 with poorly differentiated adenocarcinoma.Twenty-four patients were with lymph node metastasis.Four patients were in TNM stage Ⅰ,25 in TNM stage Ⅱ and 24 in TNM stage Ⅲ.Fifty-three patients were followed up postoperatively,and the median time for follow-up was 33 months (range,4-116 months).The overall 5-year survival rates was 57.3%.The 5-year survival rate for patients with or without lymph node metastasis were 77.1% and 30.4%,respectively,with significant difference between the 2 groups (x2 =7.374,P < 0.05).The 5-year survival rates of patients with malignant infiltration and inflammatory adhesion mere 51.0% and 68.5%,with no significant difference (x2=1.148,P >0.05).The 5-year survival rates of patients with malignant infiltration and inflammatory adhesion in stage Ⅱ were 74.6% and 85.7%,with no significant difference between the 2 groups (x2=0.118,P > 0.05).The 5-year survival rates of patients with malignant infiltration and inflammatory adhesion in stage Ⅲ were 28.8% and 37.5%,with no significant difference between the 2 groups (x2 =0.959,P > 0.05).The results of univariate analysis showed that lymph node metastasis and TNM stage were the risk factors influencing the prognosis of patients with cT4bM0 primary rectal cancer (x2=6.468,6.596,P < 0.05).The results of multivariate analysis showed that lymph node metastasis was the independent risk factor (RR =3.797,P < 0.05).Conclusions En-bloc multivisceral resection should be the first surgical treatment choice for patients with cT4bM0 primary rectal cancer,and lymph node metastasis is the independent risk factor.Under the same N stage,the prognosis of patients with malignant infiltration or inflammatory adhesion is similar if R0 resection is achieved. Key words: Rectal neoplasms ; Surgical procedures, operative; Prognosis