Is there a need for neoadjuvant short-course radiotherapy in T3 rectal cancer with positive lymph node involvement? : A single-center retrospective cohort study

Abstract Background Neoadjuvant short-course radiotherapy is used to reduce local recurrences in stage III rectal cancer. Radiotherapy is not harmless, and meticulous total mesorectal excision surgery alone has been reported to result in low local recurrence rate in favorable stage III tumors. The aim was to evaluate the effect of short-course (5 × 5 Gy) radiotherapy on the local recurrence risk in patients with pT3N1-2 rectal cancer. Materials and methods This was a retrospective study with 151 consecutive pT3N1-2M0 rectal cancer patients operated on at Helsinki University Hospital, Helsinki, Finland, during January 2005 to June 2014. Short-course radiotherapy was given to 94 patients, and 57 patients were operated on without neoadjuvant radiotherapy. The main outcome measurement was the effect of radiotherapy on local recurrence. Also, the risk factors for local recurrence were analyzed. Results Local recurrence occurred in a total 17 of 151 (11.3%) patients, 8 of 57 (14.0%) in surgery only group compared with 9 of 94 (9.6%) in radiotherapy plus surgery group (p = 0.44). In univariate Cox regression analysis, the risk factors for local recurrence were tumor location under 6 cm from the anal verge (p = 0.01), involved lateral margin (p < 0.001), tumor perforation (p < 0.001), and mucinous histology (p = 0.006). In multivariate analysis, risk factors were tumor location under 6 cm from anal verge (p = 0.03) and involved lateral margin (p = 0.002). Conclusion Neoadjuvant short-course radiotherapy did not affect the local recurrence risk of pT3N1-2M0 rectal cancer. Further studies with larger patient number are needed to evaluate the role of short-course radiotherapy in different T3 subgroups (3a–c) as well as in N1 and N2 cancers in separate