568P - Risk factors for recurrence after surgery for rectal cancer in a modern, nationwide population-based cohort

Background

The success of modern multimodal treatment in rectal cancer is dependent on risk prediction. Better knowledge of the risk of locoregional and distant recurrence, in relation to preoperative treatment, pathological stage, and commonly used risk factors, is needed when deciding on adjuvant therapy and surveillance.

Methods

The Swedish ColoRectal Cancer Registry was used to identify patients diagnosed with rectal adenocarcinoma between 2011 to 2018. Readily available variables including patient, tumour, and treatment factors were exposures. Cox proportional hazard models were used to identify important risk factors for recurrence and calculate recurrence risks.

Results

A total of 9428 curatively resected patients were included and followed for a median of 72 months. Eight-teen per cent had distal- and 3% locoregional recurrence at 5 years. Risk factors with major impact on distal recurrence were pT4a (HR 5.1, 95% CI 3.3-8.0), pN2b (HR 3.4, 95% CI 2.7-4.2), tumour deposit (HR 1.7, 95% CI 1.5-1.9), lymph node yield (HR 1.5, 95% CI 1.3-1.8), and tumour level 0-5cm (HR 1.5, 95% CI 1.3-1.8. Pathologic stage and number of risk factors identified groups with markedly different recurrence risks in all neoadjuvant treatment groups.

Conclusions

Readily available risk factors, as a complement to stage, are still valid and robust in all neoadjuvant treatment groups. Tumour deposit is important, while circumferential resection margin might no longer be important with improved oncological treatments and high-quality TME-surgery. Tailored surveillance is possible in selected groups using risk stratification based on stage and risk factors.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Center for Research and Development, Uppsala University/Region Gävleborg, Sweden grant number CFUG-978856, and the Swedish Cancer Society.

Disclosure

The author has declared no conflicts of interest.