Necessity of neoadjuvant chemoradiation therapy in extremely low rectal cancer initially requiring abdominoperineal resection retrospective study in Korea.

Purpose: This study aimed to analyze the benefit of neoadjuvant chemoradiation therapy (nCRT) versus adjuvant chemotherapy alone after surgery without nCRT on oncologic and perioperative outcomes of patients with extremely low rectal cancer requiring abdominoperineal resection (APR) when initially diagnosed.

Methods: Between March 2001 and December 2018, 88 patients who underwent APR for low rectal adenocarcinoma (anal verge < 4 cm) with clinical stage II and III (clinical T3/4, N -/+) were retrieved from a retrospective database. Sixty-eight patients received adjuvant chemotherapy alone after APR without nCRT, and 20 patients received nCRT before APR.

Results: Median follow-up was 59.7 months. The 5-year disease-free survival rate was significantly higher in the nCRT group compared to in chemotherapy alone group (85.5% vs. 58.2%, P= 0.022). The 5-year overall survival rate was also significantly higher in nCRT group compared to in chemotherapy alone group (79.6% vs. 60.0%, P= 0.042). The total recurrence rate was 45.6% in chemotherapy alone group and 15.0% in the nCRT group (P= 0.010). There was no significant difference in circumferential resection margin positive rate, postoperative morbidity, and mortality between the two groups.

Conclusion: Based on present data, the oncologic outcomes are better in nCRT compared to adjuvant chemotherapy alone after surgery without nCRT in patient with extremely low rectal cancer requiring APR initially diagnosed, even if curative resection is possible at first.