Aims: Australians have a high incidence of colorectal cancer (CRC) and it is the second leading cause of cancer death. CRC patients experience more comorbid conditions such as diabetes and heart diseases than expected from population norms. In this study we plan to describe the pattern of comorbidities in CRC cases in South Australia and compare them by site and stage.
Methods: Data from South Australia Cancer Registry and Clinical Registry were linked with hospital inpatient separations and Pharmaceutical Benefit Scheme data to acquire a dataset of CRC patients in South Australia. We have investigated the prevalence of different comorbidities by age, subsite and stage in the 12 months period prior to CRC diagnosis using the chronic comorbid conditions used by Charlson and RX-risk indices for those who had any record of hospital admission.
Results: Of 11,656 CRCs diagnosed in 2004-2013, a significant higher prevalence of comorbidity presented in colon than rectal cancer patients using either indices. The most prevalent comorbidities for colon and rectal cancers were: : hyperlipidaemia (38.4%, 33.7%), hypertension (25.9%, 22.0%), diabetes (17.3%, 15.6%) and gastric disease (11.4%, 12.4%). In younger patients (<50 years) with colon and rectal cancer diabetes (7.4%) and gastroesophageal reflux medications (17.1%) were the most prevalent comorbidities whereas, in older patients (>79 years) hypertension (36.7%, 32.7%) was the most prevalent comorbid condition for both colon and rectal cases respectively. The pattern of comorbidity did not change in different stages and hyperlipidaemia, hypertension and diabetes were the most frequent comorbidities in stages A to D.
Conclusion: Although often regarded as a single disease (CRC), colon and rectal cancers have different predisposing factors and clinical features. As expected, older patients have a higher prevalence of comorbid chronic diseases. We observe, however, that colon and rectal cancer have different comorbidity patterns by age.