Colorectal cancer survival by stage of cases diagnosed in Mallorca, Spain, between 2006 and 2011 and factors associated with survival

Abstract

Objectives: To establish cause-specific survival by stage of colorectal cancer up to 8 years from diagnosis, and to identify factors which explain and predict the likelihood of survival.

Methodology: Retrospective follow-up study of people diagnosed with invasive colorectal cancer during 2006-2011, identified through the Mallorca Cancer Registry. DCO and lymphomas were excluded. Sex, age, diagnostic method, site, histology, T, N, M, and stage, date of diagnosis, date of follow-up or death, and cause of death were collected. End point of follow-up was 31st December 2013. Multiple imputation (MI) method was performed to obtain stage when unknown. Actuarial and Kaplan-Meier methods were used for survival analysis. Extended Cox models were built to identify factors that explain and predict survival.

Results: 2889 cases were identified, 41.7% in women and 58.3% in men, with a mean age of 70.5 years. Unknown stage represented 15.3% of cases. After MI, 15% were in stage I, 26.7% were in II, 32.7% in III, and 25.6% in IV. Survival was 56% at the end of the 5th year. Survival by stage changed significantly after MI and was estimated to 83% at stage I, 73% at II, 62% at III, and 16% at IV. Extended Cox model showed that survival worsened with age, mucinous histology, and stage. Risk of dying was 17.0 times higher in stage IV compared to stage I, 3.7 times in stage III, and 1.6 times in stage II.

Conclusions: More than half of colorectal cancer patients will survive 5 years after diagnosis, but only if diagnosed in stages I-III.

Keywords: Cancer registry; Multiple imputation; Stage; Survival.