Variations in colorectal cancer pattern of care by age and comorbidity in South Australia.

This study indicates that the association of age with surgical treatment differed significantly by the CRC subsite. Comorbidity moderated the negative association of age with chemotherapy, and less so, with extent of surgery. Results were novel in indicating associations of multiple individual comorbidity types with CRC treatment modalities. The data suggest that different individual comorbidity types may have different effects on treatment and should be studied separately.