Cancer registry data based estimation of regional cancer incidence: application to breast and colorectal cancer in French administrative regions

Study objective-In many countries, cancer registries cover only a small par t of the national population. Cancer incidence far the rest off the country has therefore to be estimated. This can be done from mortality data using the relation between incidence and mortality observed in the cancer registr y areas. Such an approach was used to study geographical variation and tren d of colorectal and breast cancer incidence ire France where 10% of the nat ional population is covered by cancer registries, Design-This study applies the incidence/ mortality ratios of cancer registr y areas to regional mortality data to obtain an estimation of cancer incide nce at re given point in time. Age and period effects are included in the s tatistical models. Main results-The incidence estimations are given for 21 administrative regi ons and three time points (1985, 1990, 1995). The European standardised inc idence rates for breast cancer ranged from 86.8 to 128.8. For colorectal ca ncer, these rates ranged from 48.2 to 79.6 for men, and from 32.5 to 48.8 f or women. Breast cancer incidence has increased considerably between 1985 a nd 1995 with a higher increase in the north than in the south of France. Th e incidence of colorectal cancer has also increased, albeit to a lesser ext ent. Conclusion-The incidence estimation method proposed leads to regional incid ence rates that are useful for planning health care services on a regional basis and may also be used to study regional differences in incidence. This method is useful when only partial incidence data are available.