The optimal regimen and frequency of follow-up examinations are not well defined because the impact on patient survival is not clear and the quality of data is poor.[33,34,35]
Factors Associated with Recurrence
Diet and exercise
No prospective randomized trials have demonstrated an improvement in outcome with a specific diet or exercise regimen; however, cohort studies suggest that diet or exercise regimen may improve outcome. The cohort studies contain multiple opportunities for unintended bias, and caution is needed when using the data from them.
Two prospective observational studies were performed with patients enrolled on CALGB-89803 (NCT00003835), which was an adjuvant chemotherapy trial for patients with stage III colon cancer.[37,38] In this trial, patients in the lowest quintile of the Western dietary pattern compared with the highest quintile experienced an adjusted hazard ratio (HR) for disease-free survival of 3.25 (95% confidence interval [CI], 2.04-5.19; P < .001) and an OS of 2.32 (95% CI, 1.36-3.96; P < .001). Additionally, findings included that stage III colon cancer patients in the highest quintile of dietary glycemic load experienced an adjusted HR for OS of 1.76 (95% CI, 1.22-2.54, P < .001) compared with those in the lowest quintile. Subsequently, in the Cancer Prevention Study II Nutrition Cohort, among 2,315 participants diagnosed with colorectal cancer, the degree of red and processed meat intake before diagnosis was associated with a higher risk of death (relative risk [RR], 1.29; 95% CI, 1.05-1.59; P = .03), but red meat consumption after diagnosis was not associated with overall mortality.[Level of evidence: 3iiA]
A meta-analysis of seven prospective cohort studies evaluating physical activity before and after a diagnosis of colorectal cancer demonstrated that patients who participated in any amount of physical activity before diagnosis had a RR of 0.75 (95% CI, 0.65-0.87; P < .001) for colorectal cancer-specific mortality compared with patients who did not participate in any physical activity. Patients who participated in a high amount of physical activity (vs. a low amount) before diagnosis had a RR of 0.70 (95% CI, 0.56-0.87; P = .002). Patients who participated in any physical activity (compared with no activity) after diagnosis had a RR of 0.74 (95% CI, 0.58-0.95; P = .02) for colorectal cancer-specific mortality. Those who participated in a high amount of physical activity (vs. a low amount) after diagnosis had a RR of 0.65 (95% CI, 0.47-0.92; P = .01).[Level of evidence: 3iiB]