To investigate the role of potentially modifiable factors including access to health services and comorbidities on the differences in treatment for colorectal cancer and subsequent survival for Aboriginal and non-Aboriginal people in NSW. Adjuvant treatment patterns for Aboriginal people with colorectal cancer are described also.
Records in the NSW Central Cancer Registry for people with colorectal cancer diagnosed in 2001-2007 were linked to all NSW hospital inpatient episodes in public and private hospitals. We also collected detailed diagnosis and treatment information from medical records for 143 Aboriginal people diagnosed with colorectal cancer between the years 2000 and 2011.
Of the 29,777 eligible colorectal cancer cases, 278 (0.9%) were identified as Aboriginal. Similar proportions of Aboriginal and non-Aboriginal patients had surgery (76% v 78%, odds ratio=0.91 95% CI:0.67-1.23). Colorectal cancer-specific survival was similar for Aboriginal and non-Aboriginal patients in the first 18 months after diagnosis. However from 18 months to five years after diagnosis Aboriginal patients were twice as likely to die from their colorectal cancer as non-Aboriginal patients and this persisted after adjustment for sex, age, year of diagnosis, place of residence, spread of disease, socioeconomic disadvantage, comorbidities and surgical treatment (adjusted hazard ratio=2.43, 95% CI:1.85-3.20). Of the 143 Aboriginal patients with detailed treatment information, 117 had surgery of whom 45% had adjuvant chemotherapy and/or radiotherapy. However of the 53 patients with regional spread of disease who had surgery, 19% had neither adjuvant chemotherapy nor radiotherapy.
Aboriginal people with colorectal cancer were twice as likely to die from colorectal cancer in the period 18 months to five years after diagnosis. Possible reasons for this disparity, that will require further research, are Aboriginal people not receiving adjuvant treatment such as chemotherapy and radiotherapy, possibly due to cultural or practical barriers and differences in follow-up after initial treatment.