Pelvic wall involvement denotes a poor prognosis in T4 rectal cancer.

Purpose: An aggressive surgical approach with en bloc resection of involved structures is often possible with anterior rectal cancers that invade adjacent visceral organs, but is rarely possible in tumors that invade the pelvic wall. However, most staging systems include both situations in the same group of T4 rectal cancers. We performed a retrospective study of patients with stage T4 rectal cancer undergoing surgery to assess the influence of different organ involvement on resectability and survival.
Methods: A retrospective review was conducted of 84 patients with T4 rectal cancer treated at the University of Minnesota and affiliated hospitals over a ten-year period. Forty-seven patients (56 percent) were staged for local invasion on the basis of final pathology, 19 (23 percent) on the basis of operative findings, and 18 (21 percent) on the basis of ultrasound images. Patients were divided into two groups, those with or without pelvic wall involvement. Resectability, local control, and overall survival were compared between groups. Survival curves were estimated by the Kaplan-Meier method and compared by log-rank test. Multivariate analysis was performed with Cox proportional and logistic regression.
Results: Thirty-one patients (37 percent) had involvement of the pelvic wall, whereas 53 patients (63 percent) had visceral involvement only. All 29 patients with distant metastasis died of their disease. Forty-seven of the 55 patients without distant metastasis underwent tumor resection. Age and pelvic wall involvement were the only two factors independently associated with the probability of resection in logistic regression analysis (P = 0.0067 and P = 0.037, respectively). The only factor that affected median survival in patients without distant metastasis was tumor resection (49.1 months for resection vs. 6.1 months for no resection, P = 0.017). Patients with visceral involvement had a longer median survival (49.2 months) than those with pelvic wall involvement (13.2 months), but the difference did not reach statistical significance (P = 0.058).
Conclusion: Rectal cancers with pelvic and visceral involvement have different rates of resectability and median survival. These differences should be reflected in the TNM classification system.