R1 rectal resection: look up and don't look down.

Background: After rectal resection for adenocarcinoma, pathological examination may reveal invasion of the distal margin (DM) and/or a circumferential resection margin of the tumor (CRM-T) or of involved nodes (CRM-N) less than or equal to 1 mm. Such findings transform a planned R0 resection to R1.

Aim: : The aim was to analyze the impact of an R1 resection on prognosis, recurrence rate, and choice of adjuvant treatment.

Patients And Methods: All R1 resections observed between 2006 and 2011 were retrospectively collected. Patients were matched with 80 patients with R0 resections according to age, body mass index, gender, neoadjuvant treatment, type of resection, ypT/pT stages, and N stage.

Results: Among 472 rectal resections performed, 40 (8.5%) were R1 (CRM-T=34; CRM-N=11; invaded DM=4). Among the 4 patients with invaded DM, 3 underwent salvage abdominoperineal resection. Of the 12 patients who had not received neoadjuvant treatment, 5 received adjuvant radiotherapy. Mean follow-up was 49.3±29.3 months for the 120 patients; 5-year overall survival (OS) and disease-free survival (DFS) were 72% and 56%. Comparison between R0 and R1 resections showed a trend toward worse OS in R1 resections: 62% versus 79% (P=0.0954), a significantly worse DFS: 41% versus 65% (P=0.0267). Local recurrence rates were similar: 12% versus 13% (P=0.9177), whereas distant recurrence was significantly more frequent after R1 resection: 56% versus 26% (P=0.0040).

Conclusions: R1 resection is associated with a worse prognosis, but local recurrence rate does not differ significantly from matched R0 resections. The difference was observed for distant recurrences, especially lung, favoring the use of chemotherapy and close surveillance of the thorax.