Objective: To examine the effect of preoperative radiotherapy (PRT) on patients who undergo rectal resection with total mesorectal excision (TME) for stage T3 low rectal cancers. Summary Background Data: Evidence for the value of PRT before rectal cancer surgery is weakened by variability in the use of TME. Many surgeons have concluded that PRT is unnecessary for small rectal tumors if TME is performed, but there are no prospective data to support this opinion. Methods: Since 1980, 2,200 patients with rectal cancer have been enrolled in a prospective database. Of these, 259 underwent curative anterior or abdominoperineal resection with TME for pathologically confirmed T3 lesions within 8 cm of the anal verge. Patients were grouped by receiving PRT (n = 92) or not receiving PRT (n = 167). Five-year overall survival and 5-year local recurrence rates were evaluated. Results: Overall survival was increased from 52% in patients not receiving PRT to 63% in those receiving PRT. PRT increased overall survival for node-negative patients from 58% to 82%, with no benefit for node-positive patients. There was no significant difference in local recurrence rates. When categorized by tumor size, there was no difference in overall survival or local recurrence for 0- to 2-cm tumors or those larger than 5 cm, but PRT increased overall survival from 50% to 72% for patients with 2- to 5-cm tumors. Similar results were observed for patients with tumors staged as T3 on preoperative endoluminal ultrasound. Conclusions: Patients with pT3 low rectal cancers undergoing resection with TME have an improved survival with PRT. The effect is most beneficial for patients with node-negative and 2- to 5-cm tumors, although this group may include larger and node-positive tumors that have been downstaged by PRT. PRT should be advocated for all patients with T3 rectal cancers less than 8 cm from the anal verge, even if the surgery includes a properly performed TME.
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