Staging and survival of rectal cancer in Vila Nova de Gaia, Portugal

Abstract

In the county of Vila Nova de Gaia (northern Portugal) in the period of 2004-2006, there were an average of 35 new cases of colorectal cancer per 100,000 population, which constitutes one of the highest rates in the world. The latest research has shown that there are many differences between colon and rectal cancers, thereby justifying an independent approach. The study pertained to the period 1995-2004, by using the census of 1991 and 2001 for calculating specific rates. The 399 diagnosed cases of rectal cancer were drawn from a specialized and active cancer registry, oncological registry of Gaia. Overall survival was calculated using the Kaplan-Meier method and the curves were compared using a Log Rank test. The effect of topography and histological type on survival was obtained by controlling the stage disease, using a Cox proportional hazards regression model. There was a slight predominance of males, with a ratio between sexes of 1 : 3. The 50% overall survival rate after 5 years increased over time. The localization of the tumour and the histological type, after adjusting by stage, were not significant factors in the prognosis. Our study shows an increase in the number of cases over time, particularly in elderly women. The cumulative risk of having rectal cancer remains unchanged from 1981 to 2004. Unlike other studies, an increase in early lesions was not observed.