For the study area, we calculated expected numbers of cancers as the number of subjects multiplied by reference incidence rate for that cancer by sex, age, time period, SES, distance to sea, and distance to river.
Otherwise known as rate multipliers, IRRs indicate the relative impact of a covariate on a reference incidence rate, here represented by the estimated intercept (which reports the incidence rate of drug utilization per 100,000 individuals).
The capital cities of these northernmost and southernmost states are located at 27.5º south and 42.9º south, respectively (table 1). Figure 1 shows the pattern of risk for multiple sclerosis for each two month period of birth, expressed as an incidence rate ratio for each period of birth relative to the reference incidence rate ratio (1.0) for May-June.
Assuming independence, the risk expressed in breast-years would be twice as high as in breast cancer survivors only one breast is at risk for CBC and the reference incidence rates concern cancer in any of two breasts.
We then calculated the number of iNTS cases for each country by using the reference incidence rates from the cell, according to the assignment of each country in the matrix and each country's population stratified by age groups.
External reference incidence rates for leukaemia were calculated from published general population French cancer registers (Bas-Rhin, Doubs and Isère 1978 1992, Calvados 1978 1987, Haut-Rhin 1988–1992) (IARC, 1987; IARC, 1992; IARC, 1997).
Follow-up did not stop at the date of first diagnosis of cancer, and so all primary cancers diagnosed during the follow-up were counted as observed cases and included in the reference incidence rates.
The expected number of cases was calculated using normal population-based age- and sex-specific reference incidence rates from a recently published study on diabetes incidence in the Kronoberg county of southern Sweden (15) and correspondingly stratified patient-years in KIMS.
We estimated reference incidence rates separately for total Finnish population and Finnish farmers, dividing the number of new cases of cancer by the population at risk in 1980, by sex, age, time period, and SES (in analyses of all people but not farmers).
Expected numbers of cases for each block group were computed by applying reference incidence rates for the same years (as estimated from the four administrative departments of the study area, plus the departments of Doubs and Hérault) to the person-years of each area stratified by gender and 5-year age classes.
However, the age-specific HNC-to-reference incidence rate ratio decreased with aging, with the highest noted in those HNC patients younger than 40 years (HR: 5.76, 95% CI: 3.99 8.33).
