Disparités géographiques d’évolution d’incidence des cancers de la thyroïde par taille entre 1983 et 2000 en France

BackgroundThe aim of this investigation was to study geographic time trends of thyroid cancer incidence according to tumor size in France, 1983 to 2000.MethodsIncidence data were provided from six French registries over the period 1983–2000 covering seven administrative districts. Five tumor size groups were distinguished: < 10 mm, 10–20 mm, 20–40 mm, > 40 mm and unknown size. Papillary cancers diagnosed in women were analyzed according to tumor size in each geographic area. World age standardized rates were calculated and annual percent change rates were estimated for each tumor size group in each geographic area. Loglinear Poisson regression models were used to study geographic discrepancies in time trends incidences.ResultsThe six French registries included 2222 papillary thyroid cancers in women between 1983 et 2000. Thyroid cancer incidence was increasing in the six geographic areas. Geographical variations in time trends incidence between registries reflected geographical variations in time trends incidence of small sized tumors (less than 10 mm).ConclusionWide geographic variations in thyroid cancer incidence were noticed for small size tumors, which may be correlated with geographic variations in medical practices.     

Fine‐mapping of two differentiated thyroid carcinoma susceptibility loci at 9q22.33 and 14q13.3 detects novel candidate functional SNPs in Europeans from metropolitan France and Melanesians from New Caledonia

Incidence of differentiated thyroid carcinoma varies considerably between countries and ethnic groups, with particularly high incidence rates in Melanesians of New Caledonia. Differentiated thyroid cancer (DTC) has a familial relative risk higher than other cancers, highlighting the contribution of inherited factors to the disease. Recently, genome‐wide association studies (GWAS) identified several DTC susceptibility loci. The most robust associations were reported at loci 9q22 (rs965513 and rs1867277) and 14q13 (rs944289 and rs116909734). In this study, we performed a fine‐mapping study of the two gene regions among Europeans and Melanesians from Metropolitan France and New Caledonia. We examined 81 single nucleotide polymorphisms (SNPs) at 9q22 and 561 SNPs at 14q13 in Europeans (625 cases/776 controls) and in Melanesians (244 cases/189 controls). The association with the four SNPs previously identified in GWAS was replicated in Europeans while only rs944289 was replicated in Melanesians. Among Europeans, we found that the two SNPs previously reported at 9q22 were not independently associated to DTC and that rs965513 was the predominant signal; at 14q13, we showed that the haplotype rs944289[C]‐rs116909374[C]‐rs999460[T] was significantly associated with DTC risk and that the association with rs116909374 differed by smoking status (p‐interaction = 0.03). Among Melanesians, a new independent signal was observed at 14q13 for rs1755774 which is strongly correlated to rs2787423; this latter is potentially a functional variant. Significant interactions with parity (p < 0.05) and body mass index were observed for rs1755774 and rs2787423. This study contributed to a better characterization of the DTC loci 9q22 and 14q13 in Europeans and in Melanesians and has identified novel variants to be prioritized for further functional studies.     

Second primary malignancies in thyroid cancer patients

The late health effects associated with radioiodine ((131)I) given as treatment for thyroid cancer are difficult to assess since the number of thyroid cancer patients treated at each centre is limited. The risk of second primary malignancies (SPMs) was evaluated in a European cohort of thyroid cancer patients. A common database was obtained by pooling the 2-year survivors of the three major Swedish, Italian, and French cohorts of papillary and follicular thyroid cancer patients. A time-dependent analysis using external comparison was performed. The study concerned 6841 thyroid cancer patients, diagnosed during the period 1934-1995, at a mean age of 44 years. In all, 17% were treated with external radiotherapy and 62% received (131)I. In total, 576 patients were diagnosed with a SPM. Compared to the general population of each of the three countries, an overall significantly increased risk of SPM of 27% (95% CI: 15-40) was seen in the European cohort. An increased risk of both solid tumours and leukaemias was found with increasing cumulative activity of (131)I administered, with an excess absolute risk of 14.4 solid cancers and of 0.8 leukaemias per GBq of (131)I and 10(5) person-years of follow-up. A relationship was found between (131)I administration and occurrence of bone and soft tissue, colorectal, and salivary gland cancers. These results strongly highlight the necessity to delineate the indications of (131)I treatment in thyroid cancer patients in order to restrict its use to patients in whom clinical benefits are expected.