The use of adjuvant chemotherapy is not associated with recurrence or cancer-specific death following curative resection for stage III rectal cancer: a competing risks analysis

Background: The role of adjuvant chemotherapy (AC) in stage III rectal cancer (RC) has been argued based on evidence from its use in colon cancer. Previous trials have analysed disease-free and overall survivals as endpoints, rather than disease recurrence. This study compares the competing risks incidences of recurrence and cancer-specific death between patients who did and did not receive AC for stage III RC. Methods: Consecutive patients who underwent a potentially curative resection for stage III RC (1995–2019) at Concord Hospital, Sydney, Australia, were studied. AC was considered following multidisciplinary discussion. Primary outcome measures were the competing risks incidences of disease recurrence and cancer-specific death. Associations between these outcomes and use of AC (and other variables) were tested by regression modelling. Results: Some 338 patients (213 male, mean age 64.4 years [SD12.7]) were included. Of these, 208 received AC. The use of AC was associated with resection year (adjusted OR [aOR] 1.74, 95%CI 1.27–2.38); age ≥75 years (aOR0.04, 95%CI 0.02–0.12); peripheral vascular disease (aOR0.08, 95%CI 0.01–0.74); and postoperative abdomino-pelvic abscess (aOR0.23, 95%CI 0.07–0.81). One hundred fifty-seven patients (46.5%) were diagnosed with recurrence; death due to RC occurred in 119 (35.2%). After adjustment for the competing risk of non-cancer death, neither recurrence nor RC-specific death was associated with AC (HR0.97, 95%CI 0.70–1.33 and HR0.72, 95%CI 0.50–1.03, respectively). Conclusion: This study found no significant difference in either recurrence or cancer-specific death between patients who did and did not receive AC following curative resection for stage III RC.