Colon Cancer, Prognosis After Surgery : What Are the Risks of Recurrent Disease, and How Do We Find Those at Risk?

Abstract: Colon cancer is the fourth most common cancer worldwide with approximately 1.2 million yearly cases. Developments in the standard of care have improved prognosis. In Paper I the recurrence risk was investigated in a national material consisting of 14,325 colon cancer patients. Three fourths of stage II patients have a risk of approximately 11%, indicating that adjuvant chemotherapy can marginally improve prognosis. In stage III, one fifth of the patients have such a low risk of recurrence that the addition of a second chemotherapeutic drug, oxaliplatin with its risk for late toxicity, may be questioned. In Paper II emerging risk factors were investigated in a thoroughly staged and described material of 416 colon cancer patients from one county. All emerging risk factors correlated with an increased recurrence risk. Adjusting for established risk factors, pN-substage and postoperative carcinoembryonic antigen (CEA) correlated independently with recurrence. Paper III investigated the completeness and correctness of recurrences in the Swedish Colorectal Cancer registry in 2,893 patients from two counties. In patients operated more than 5 years ago 2% of recurrences were not registered. In Paper IV a nomogram for clinicians was developed using registry data to aid the interpretation of the recurrence risk and discussion with patients about treatment choices. It was validated in Norwegian cancer registry data and performed better than other available nomograms.Future investigations of the cohort from paper II are planned with immunohistochemistry, tumour-normal tissue sequencing and biomarkers.In summary, recurrence rates have decreased since the early 2000s and a large proportion of patients can probably be spared some or all adjuvant treatment. Established risk factors describe a large part of the risk, but there is room for improvement. The biomarker CEA taken after surgery could aid in the selection of patients to receive adjuvant treatment and guide follow-up. Adding other biomarkers might further improve the prediction of recurrence risk, though larger, prospective patient materials are needed.