Background: No previous Australian population-based studies have described or quantified the progression of colorectal cancer (CRC) to metastatic disease. We describe patterns of progression to metastatic disease for an Australian cohort diagnosed with localised or regional CRC.
Methods: All localised and regional CRC cases in the New South Wales Cancer Registry diagnosed during 2000-2007 were followed to December 2011 for subsequent metastases (identified by subsequent disease episode notifications) or CRC death. Cox regression was used to identify factors associated with metastatic progression.
Results: After a median 5.3 years follow-up, 26.4% of the 12757 cases initially diagnosed with localised or regional colon cancer had developed metastatic disease, as had 29.5% of the 7154 rectal cancer cases. For both cancer sites, risk of metastatic progression was significantly higher for those initially diagnosed with regional disease (adjusted hazard ratio [aHR] 3.49 for colon, 2.66 for rectal cancer), and for older cases (e.g. aHR for >79years vs <60years: 1.38 for colon, 1.69 for rectal cancer). Risk of disease progression was significantly lower for females, and varied by histology type. For colon cancer, the risk of disease progression decreased over time. For rectal cancer, risk of metastatic progression was significantly higher for those living in more socioeconomically disadvantaged areas compared with those in the least disadvantaged area.
Conclusions: An understanding of the variation in risk of metastatic progression is useful for planning health service requirements, and can help inform decisions about treatment and follow-up for colorectal cancer patients.
Keywords: Cancer registry; Colorectal cancer; Histology type; Metastatic progression; Population-based study; Primary tumour location; Socio-economic status; Stage at diagnosis.
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