An analysis of competing mortality risks among colorectal cancer survivors in Queensland, 1996–2009

Abstract

Colorectal cancer survivors are at risk of dying from other causes including comorbidities and second malignancies. This study was undertaken to identify demographic and clinical predictors of cancer-specific and competing causes of mortality. The crude probabilities of mortality attributed to colorectal cancer, other cancers, and non-cancer causes were estimated for 19,415 residents of Queensland, Australia, who were diagnosed with a first primary colorectal cancer between 1996 and 2007 when aged 20-79 years and survived at least 2 months, with follow-up to the end of 2009. Multivariate competing risk analysis was used to analyze covariate effects on the cumulative probability of the different mortality types. Five-year cumulative probabilities of colorectal cancer, other cancers, and non-cancer mortality were 29.4 % (95 % CI 29.3, 30.7), 2.0 % (95 % CI 1.8, 2.2), and 5.7 % (95 % CI 5.3, 6.0), respectively. Factors associated with an increased risk of non-cancer mortality included older age, male gender, unmarried status, localized disease, first primary colon cancers, no surgery, and the presence of comorbidities. Apart from diagnosis of a metachronous secondary cancer, being older, unmarried, or in blue-collar occupations were independent predictors of increased mortality due to other cancers. A better understanding of the role of competing events and the ability to predict risk of such events have the potential to translate into more effective individualized strategies for colorectal cancer management. The control of comorbidities and reducing cancer risk through clinical management and lifestyle changes should be an important and attainable goal for CRC survivors.