Factors associated with lateral pelvic recurrence after curative resection following neoadjuvant chemoradiotherapy in rectal cancer patients.

PURPOSE: This study aims to determine the risk factors for lateral pelvic recurrence (LPR) in rectal cancer patients treated with neoadjuvant chemoradiotherapy (CRT) and curative surgery.

METHODS: Four hundred forty-three patients treated with neoadjuvant CRT and curative surgery from October 1999 through June 2009 were analyzed. All patients underwent total mesorectal resection without lateral pelvic lymph node (LPLN) dissection. Recurrence patterns and lateral pelvic recurrence-free survival (LPFS) were evaluated relative to clinicopathologic parameters including pelvic LN status.

RESULTS: Median follow-up was 52 months, with locoregional recurrence in 53 patients (11.9 %). Of the 53 patients, 28 (52.8 %) developed LPR, of which eight had both central and lateral PR. Multivariate analysis showed a significant relationship between LPFS and the number of lateral pelvic LN (p = 0.010) as well as the ratio of the number of positive LN/number of dissected LN (p = 0.038). The relationship between LPFS and LPLN size had a marginal trend (p = 0.085). Logistic regression analysis showed positive relationships between LPR probability and the number of LPLN (odds ratio [OR] 1.507; 95 % confidence interval [CI] 1.177-1.929; p = 0.001) as well as LPLN size (OR 1.124; CI 1.029-1.227, p = 0.009).

CONCLUSIONS: LPLN ≥ 2 and a ratio of the number of positive LN/number of dissected LN > 0.3 were prognostic of poor LPFS. The prediction curve of LPR according to the number and size of LPLN could be useful for determining the benefit of additional lateral pelvic treatment.