Variation in cancer incidence in northeastern Belgium and southeastern Netherlands seems unrelated to cadmium emission of zinc smelters.

Exposure to cadmium has been established to be carcinogenic for humans by the International Agency for Research on Cancer, but this is mainly based on studies with occupational exposures. The substantial 100 year long emission of cadmium by three zinc smelters in the Kempen area across the Dutch-Belgian border might have affected the incidence of cancer in this region. Following a study of increased risks of lung cancer due to cadmium emission (hazard ratio was 4.2 for high vs. low cadmium exposure areas in that study), we used data from the three regional population-based cancer registries, covering an area with 2.9 million inhabitants. Analyses of observed incidence were carried out for all cancers and cancer of the lung, kidney, bladder, prostate, testis, and breast separately. At the municipality level standardized incidence ratios were calculated and smoothed using a Poisson-gamma or a conditional autoregressive model. To detect clusters and to calculate an observed/expected ratio (O/E ratio) for each cluster a spatial scan statistic was applied. Significantly increased cancer incidence rates were found at a multimunicipality level for female lung cancer (O/E ratio=1.2), male and female bladder cancer (O/E ratio male=1.8, O/E ratio female=1.7), and prostate cancer (O/E ratio=1.3), none of these clusters being located specifically around the area of the zinc smelters. Therefore, the long term emission of cadmium by the zinc smelters in the Kempen area did not seem to lead to an increase in the incidence of all cancers, and lung, kidney, bladder, prostate, testicular, or breast cancer.

Reduction in hormone replacement therapy use and declining breast cancer incidence in the Belgian province of Limburg.

Breast cancer is the most common female cancer in Europe, but its incidence and mortality are rapidly changing across Europe. The early termination of the women's health initiative (WHI) trial, after the detection of an increased breast cancer risk in hormone replacement therapy (HRT) users, was followed by strong declines of HRT use worldwide. We investigated whether the reduction of HRT sales affected breast cancer incidence in the Belgian province Limburg. All women registered in the Limburg Cancer Registry with a diagnosis of invasive breast cancer diagnosed between 1/1/1996 and 31/12/2005 were included in the study. Data on the use of HRT in the population were obtained from the vendors and the social security system. For age-standardization using the direct method, the European standard population was taken. In 2003 and 2004, the breast cancer incidence rate decreased significantly as compared to 2002 for women aged between 50 and 69 years. This sudden drop in the incidence intercepted a markedly increasing trend until 2002, but was followed again by an increase in 2005. Between 2002 and 2006, the sales of HRT (about 75% to women aged 50-69 years) were reduced by 41%. Breast cancer incidence was maximally related to HRT use in the previous year (R(2) = 77%). The decrease of breast cancer incidence in the Belgian province of Limburg may largely be related to the fall of HRT use following the early termination of the WHI trial. This suggests that HRT stimulates the growth of pre-existing, clinically latent tumours that may not otherwise become clinically apparent.

A quasi-randomized trial on the effectiveness of an invitation letter to improve participation in a setting of opportunistic screening for cervical cancer.

The objective of the study was to assess the effect of an invitation letter on the level of participation in a setting of mainly opportunistic screening for cervical cancer and to do a cost analysis of this intervention. We designed a quasi-randomized trial in which a sample of women between the ages of 25 and 64 years and residing in the province of Limburg, Belgium, who had no Pap smear taken in the past 30 months according to LIKAR (Limburg Cancer Registry), were assigned to an intervention group or to a control group. A written invitation was sent to 43 523 women in the intervention group. Baseline participation in cervical screening was recorded in the year before the intervention to determine its effect. Differences in cumulative incidence between the intervention and the control group were used to report the effect. The net effect of a written invitation resulted in 3355 more women undergoing a Pap smear, which is an increase of 6.4% (95% confidence interval: 5.9-6.9). The cost per additional Pap smear taken amounted to euro29.8. Within an opportunistic cervical cancer screening setting, the effect of a registry-based invitational programme to nonattenders increases the participation further, and at no extra cost compared with an invitational programme to all screen-eligible women irrespective of their screening status.