Geographical variation in cancer patient survival in Finland: chance, confounding, or effect of treatment?

STUDY OBJECTIVE The aim was to determine whether survival of cancer patients in Finland varies with their place of residence, and if so, what proportion of the variation might be due to health services rather than to confounding variables. DESIGN Patients with breast and prostatic cancer diagnosed in Finland between 1970 and 1981 were classified by place of residence (from 21 hospital districts), and area specific 5 year relative survival rates were estimated. SETTING This was a population based survey of the whole of Finland. PATIENTS 16,754 cases of breast cancer and 9483 cases of prostatic cancer were identified. Of these, 0.5% of breast cancers and 4.1% of prostatic cancers were excluded because diagnosis was based only on necropsy findings or because the only information available was from the death certificate. MEASUREMENTS AND MAIN RESULTS There was a large variation in rates, ranging from 59% to 76% for breast cancer, and from 30% to 65% for prostatic cancer. However, after accounting for age of patient and extent of disease, the standardised differences for prostatic cancer closely followed random distribution, indicating equal results of treatment in different areas. For breast cancer there was more variation than expected by chance and patients resident in any of the university central hospital districts with modern radiotherapy equipment survived better than other patients. CONCLUSIONS There is little indication that large variations in crude mortality rates from these two cancers in different parts of Finland are due to inequalities of medical care, though a small effect on breast cancer survival which might be care related was shown.