Minimum radial margin in pelvic exenteration for locally advanced or recurrent rectal cancer.

PURPOSE: The aim of this study was to clarify the suitable radial margin (RM) for favourable outcomes after pelvic exenteration (PE), focusing on the discrepancy between the concepts of circumferential resection margin (CRM) and traditional R status.

METHODS

Seventy-three patients with locally advanced (LARC, n = 24) or locally recurrent rectal cancer (LRRC, n = 49) who underwent PE between 2006 and 2018 were retrospectively analysed. Patients were histologically classified into the following 3 groups; wide RM (≥1 mm, n = 45), narrow RM (0-1 mm, n = 10), and exposed RM (n = 18). The analysis was performed not only in the entire cohort but also in each disease group separately.

RESULTS

The rates of traditional R0 (RM > 0 mm) and wide RM were 75.3% and 61.6%, respectively, resulting in the discrepancy rate of 13.7% between the two concepts. Preoperative radiotherapy was given in 12.3%. In the entire cohort, the local recurrence and overall survival (OS) rates for narrow RMs were significantly worse than those for wide RMs (p < 0.001 and p = 0.002), but were similar to those for exposed RMs. In both LARC and LRRC, RM < 1 mm resulted in significantly worse local recurrence and OS rates compared to the wide RMs. Multivariate analysis showed that RM < 1 mm was an independent risk factor for local recurrence in both LARC (HR 15.850, p = 0.015) and LRRC (HR 4.874, p = 0.005).

CONCLUSIONS

Narrow and exposed RMs had an almost equal impact on local recurrence and poor OS after PE. Preoperative radiotherapy might have a key role to ensure a wide RM.