BC Cancer Agency, Vancouver, BC, Canada
Richard M. Lee-Ying , Daniel John Renouf , Howard John Lim , Hagen F. Kennecke , Sharlene Gill , Caroline Speers , Winson Y. Cheung
Background: Surveillance is frequently conducted after the completion of curative treatment in early stage cancers to detect resectable recurrences. As more stage IV patients undergo curative resection of metastases (CRM), surveillance of such cases is increasingly performed, but its utility is unclear. Using a cohort of metastatic colorectal cancer (mCRC) patients, we aimed to 1) characterize surveillance patterns in a population-based setting and 2) examine if surveillance contributed to improved outcomes. Methods: Patients diagnosed with mCRC from 1995 to 2010 and referred to any 1 of 5 cancer centers in British Columbia were reviewed. Using Cox regression models that adjusted for confounders, we identified predictors of overall survival (OS) in patients who underwent CRM. Recurrences were categorized into those detected by surveillance vs symptoms and whether further attempts at CRM were feasible. Results: We identified 2082 mCRC patients of whom 254 proceeded to CRM. Median age was 63, 52% were men, 44% had de novo stage IV disease, 56% received perioperative chemotherapy, and 17%/66% had lung/liver metastases, respectively. Surveillance practices after CRM varied widely, but included clinical examination (85%), CEA (86%), imaging (89%) and endoscopy (28%) in the first 5 years. The median OS of CRM cases was 40.9 months, including 191 (75%) recurrences. The median time to recurrence was 10.2 months. Recurrences were detected by surveillance in 152 (80%) cases, and proceeded to a second CRM in 41 (21%). Compared to recurrences detected by symptoms, those based on surveillance were more likely to proceed to another CRM (25% vs. 11%, p < 0.001). Adjusting for confounders, surveillance (HR 0.61 95% CI 0.39-0.94, p = 0.026) and a second CRM (HR 0.53, 95% CI 0.34-0.82, p = 0.004) were independently correlated with improved OS. Conclusions: In this population-based cohort of mCRC patients, the majority recurred after the initial CRM, but recurrences detected by surveillance were more amenable to a subsequent CRM. While surveillance was performed in most cases, significant variations in practice were observed, underscoring the need for wider dissemination of evidence-based guidelines for the surveillance of selected metastatic disease.
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