Cancer and cancer risk in South Australia: what evidence for a rural-urban health differential?

OBJECTIVE: To determine the extent of evidence for a rural-urban health differential in cancer and cancer risk in South Australia.
DESIGN: Secondary analysis and synthesis of data available between 1977 and 2000 from the publications of the South Australian Cancer Registry and reports of population health surveys carried out by the South Australian Department of Human Services.
RESULTS: The mean annual age-standardised incidence of all forms of cancer combined was about 4% lower for rural residents (265.2 per 100,000 cf. 274.9 per 100,000). Of 31 types of cancer listed, the incidence of three was significantly higher among rural residents, the incidence of eight was significantly higher among urban residents and for 20 types there was no significant difference. Five year case survival for all cancers combined was 52% in both urban and rural residents. Significant survival differences were identified for only 10 cancers and survival for each was higher among urban residents. Melanomas were diagnosed in situ more often in the country, but invasive cases tended to be thicker. There was no rural-urban difference in early detection rates for breast cancer or bladder cancer. There were no substantial reported differences in major risk factors and early detection experiences apart from higher rates of smoking in the country.
CONCLUSIONS: There is little evidence for substantial or systematic differences in risk factors for, and incidence and early detection of cancers between urban and rural South Australia. However, the apparent consistently poorer survival among rural residents warrants further study. WHAT THIS PAPER ADDS: It is widely reported that the health status of rural Australians is worse than that of their urban counterparts. There is an apparent increasing gradient in mortality from urban to remote areas of Australia. However, this apparent gradient is not evident for all diseases. This paper seeks to answer the question: is there any difference in the cancer disease experience (incidence, survival and early detection) and cancer risk factors between residents of rural and urban South Australia. Cancer registry data indicate that overall, the incidence of cancer is similar in rural and urban South Australia. The findings on survival differentials are of concern. While overall survival rates are very similar in country and city, and this is encouraging, analysis of individual types of cancer raises some concerns. The registry reports that significant differences in survival were only measured for 10 cancers and for all of these rural residents experienced higher mortality rates.