Importance: Oncologic outcomes among patients with rectal cancer after developing local recurrence and/or distant metastases remain poorly studied.
Objective: To analyze the trend of overall survival after treatment failure for patients with rectal cancer within three consecutive phase 2 or 3 trials of the German Rectal Cancer Study Group.
Design, setting, and participants: This cohort study is a post hoc analysis of 3 randomized phase 2 or 3 trials (CAO/ARO/AIO-94, -04, and -12 trials, conducted in Germany) that included 1948 patients with locally advanced rectal adenocarcinoma. The CAO/ARO/AIO-94 trial recruited patients between February 1995 and September 2002, the CAO/ARO/AIO-04 trial recruited patients between July 2006 and February 2010, and the CAO/ARO/AIO-12 trial recruited patients between June 2015 and January 2018. Statistical analysis was conducted between September 2022 and March 2023.
Exposures: A total of 119 of 391 patients in the CAO/ARO/AIO-94 trial group A, 295 of 1236 patients in the CAO/ARO/AIO-04 trial, and 69 of 306 in the CAO/ARO/AIO-12 trial experienced treatment failure (R2 resection or local recurrence or distant metastases) and were included in further analyses.
Main outcomes and measures: Characteristics of treatment failure and overall survival were assessed in all 3 trial cohorts.
Results: Of the 1948 patients treated in the 3 trials, 15 were excluded because of missing data. Of the remaining 1933 patients (median age, 62.5 years [range, 19-84 years]; 1363 men [71%] and 570 women [29%]) with locally advanced rectal adenocarcinoma (cT3 or 4 or cN+) treated within 3 consecutive clinical trials, 483 experienced treatment failure and were analyzed. After a median follow-up of 36 months (IQR, 24-51 months) for all patients, overall survival after treatment failure was significantly improved in the CAO/ARO/AIO-04 trial (at 3 years, 44% [IQR, 37%-51%]; hazard ratio [HR], 0.61 [95% CI, 0.47-0.79]) and further improved in the CAO/ARO/AIO-12 trial (at 3 years, 73% [IQR, 60%-87%]; HR, 0.32 [95% CI, 0.18-0.54]) compared with the CAO/ARO/AIO-94 trial (at 3 years, 30% [IQR, 22%-39%]) (both P < .001). Distant metastasis was the main reason for treatment failure throughout a 5-year follow-up (range, 67%-87%), and the relative risk for treatment failure was highest in the first 18 months in all 3 trials. ypTNM stage was significantly associated with the risk and time interval to treatment failure. Improvement in overall survival after treatment failure was independent of sex.
Conclusions and relevance: This cohort study suggests that advancements in salvage strategies during the past decades have likely improved overall survival among patients with rectal cancer who experienced treatment failure.