CIRCUMFERENTIAL MARGIN INVOLVEMENT AFTER MESORECTAL EXCISION OF RECTAL-CANCER WITH CURATIVE INTENT - PREDICTOR OF SURVIVAL BUT NOT LOCAL RECURRENCE

PURPOSE: This study examines the prognostic significance of circumfere ntial margin involvement by tumor in resected specimens after potentia lly curative rectal cancer surgery. METHODS: During an eight-year peri od, all patients with rectal cancer were prospectively audited. For tu mors of the middle and lower thirds of the rectum, a total mesorectal excision was performed; for tumors of the upper third, mesorectal exci sion proceeded at least 5 cm distal to the primary tumor. Resected spe cimens were subjected to careful histologic assessment, and patients u ndergoing curative procedures were entered into a surveillance program to detect both local and distant recurrence. RESULTS: Of 218 patients in the cohort, 9 had no resection, 14 underwent local excision, 1 had pre-operative radiotherapy, and 42 patients (20 percent) had palliati ve resections and were excluded from further analysis. This left 152 p atients having a curative resection, of whom 20 (13 percent) had tumor within 1 mm of the circumferential margin. After follow-up until deat h or a median period of 41 months, recurrent disease was seen in 24 pe rcent of patients with a negative margin and 50 percent with a positiv e margin. Both disease-free survival and mortality were significantly related to margin involvement (log-rank, P = 0.01 and P = 0.005, respe ctively). Local recurrence, however, was not significantly different i n the two groups (11 and 15 percent, respectively; log-rank, P = 0.38) . CONCLUSIONS: When a mesorectal excision is performed, circumferentia l margin involvement is more an indicator of advanced disease than ina dequate local surgery. Patients with an involved margin may die from d istant disease before local recurrence becomes apparent.