It is estimated that in 2018 there were 1.8 million patients diagnosed with colorectal cancer (CRC) worldwide resulting in 862,000 deaths, which is an increase from 2012 by 33% and 24%, respectively ( ). Surgical resection remains the standard of care for resectable, non-metastatic, CRC. Following complete resection, more than 90% of recurrences occur in the first 5 years with most occurring in the first 3 years ( ). Beyond 5 years, however, there are currently no clear recommendations. There are some studies with up to 10 years of follow-up after surgery that have reported late recurrences after 5 years ( ), thus the utility of prolonged follow-up after the initial 5 years is an important question. To address this knowledge gap, Kong investigated the efficacy of prolonged follow-up beyond 5 years using a retrospective cohort of 1,054 CRC patients who underwent radical resection from 1980 to 1996 at their institution ( ). The patient cohort consisted of 15% right-sided colon tumors, 18% left-sided colon tumors, and 62% rectal tumors. Pathological stages included 14% stage I, 56% stage II, and 31% stage III. Patients were followed every 3 months for the first 2 years, every 6 months in the following 3 years, and then yearly. To detect local or distant recurrence, the authors utilized a physical exam, ultrasound, X-ray, and computed tomography. The authors found significant associations between survival and the following variables: age (P=0.026), tumor site (P<0.001), and pathologic stage (P<0.001). Compared to patients who died within 5 years of surgery, patients who survived past 15 years had a higher proportion of colon cancer relative to rectal cancer and stage I/II disease. Furthermore, 91% of relapses occurred in the first 5 years after surgery, whereas less than 1% of patients relapsed after 15 years of surveillance.
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