To Örebro University

BACKGROUND/AIM: The optimal treatment sequencing for asymptomatic de novo metastatic rectal cancer is unclear. The aim of this study was to investigate the role of upfront radiotherapy, with or without chemotherapy on risk for local complications, in patients with asymptomatic advanced metastatic rectal cancer treated with palliative intention.

PATIENTS AND METHODS: All patients with de novo metastatic rectal cancer diagnosed between January 2008 and December 2017 in two healthcare regions in Sweden (Örebro län, Sörmland) were identified and data were extracted from electronic medical records. Patients were divided into 3 groups based on treatment sequence: upfront radiotherapy, upfront chemotherapy, and only palliative surgery.

RESULTS: In total, 102 patients were included in the study cohort, 30 patients in upfront radiotherapy group, 54 in upfront chemotherapy, and 18 in only palliative surgery group. Patients with only upfront CT [odds ratio (OR)= 5.10; 95% confidence interval (CI)=1.24-20.91, p=0.024] had a higher risk to suffer from a local complication compared to those who received upfront radiotherapy. Cause-specific Cox regression analysis among patients who received oncological therapy revealed that female patients [cause-specific hazard ratio (csHR)=3.61; 95% confidence interval (CI)=1.67-7.81] and upfront chemotherapy [csHR=1.85; 95% CI=1.11-3.77] were associated with increased cumulative incidence of local complication over time, whereas primary surgery with ostomy or stent with lower risk [csHR=0.45; 95% CI=0.21-0.99].

CONCLUSION: Patients who received upfront radiotherapy, with or without chemotherapy, had fewer local complications due to primary tumor compared to patients who only received chemotherapy. This could indicate that radiotherapy to the primary tumor could be discussed with the patients as a first treatment option for asymptomatic metastatic rectal cancer to prevent local complications later during the disease.