Duration of symptoms, stage at diagnosis and relative survival in colon and rectal cancer

In colorectal cancer, the relation between duration of symptoms and stage at presentation and prognosis is not yet settled. All 1263 patients treated for colorectal cancer at Levanger Hospital, 1980-2004, and 2892 patients treated in Norway during 2004 were included. The association between symptom duration as an explanatory variable and tumour stage as a dependent variable was analysed using a proportional odds logistic regression model. Known duration of symptoms was divided into four categories: <1 week, 1-8 weeks, 2-6 months and >6 months. There was an inverse relationship between symptom duration and colon cancer TNM-stage, OR=0.73 (95% CI 0.63-0.84), p<0.001 (Levanger Hospital) and 0.84 (0.75-0.95), p=0.004 (Norway 2004), where the OR is per category of symptom duration. Duration of symptoms were also inversely associated with T-stage, N-stage and M-stage in colon cancer. These relationships were not found for rectal cancer. In colon cancer the relative five-year survival for the four intervals of symptom duration was 44%, 39%, 54% and 66%, p<0.001, in Levanger, 1980-2004, and four-year survival was 46%, 62%, 75% and 74%, p<0.001, in Norway 2004, respectively. For rectal cancer survival was not dependent on symptom duration. In a multivariate analysis of relative survival of patients with colon cancer, duration of symptoms was associated with survival independent of tumour differentiation and TNM-stage. Increasing duration of symptoms was positively associated with less advanced disease and better survival in colon cancer, but not in rectal cancer.