Risk of differentiated thyroid cancer in relation to adult weight, height and body shape over life: The French E3N cohort

Abstract

The increasing incidence rate of thyroid cancer warrants investigation of potentially modifiable factors, especially overweightness. Few prospective studies have investigated anthropometry from childhood to adulthood in relation to thyroid cancer. We analyzed data from 91,909 women of the E3N study, a cohort of French women insured by a national health scheme mostly covering teachers with the age of 40-65 years at inclusion in 1990. Risk estimates of first primary differentiated thyroid cancer (n 5 317) were computed using Cox proportional hazards models. There was a significant doseeffect relationship between thyroid cancer risk and weight or body mass index (BMI) but not height. Compared with women whose BMI was 18.5-22 kg/m 2 , women with BMI 22-25 and those with BMI over 30 had a 39% [95% confidence interval (CI) 7-81] and 76% (12-176) higher risk of thyroid cancer, respectively, with a 21% (5-39) increased risk per 5 kg/m 2 increase in BMI. A large body shape from age 35-40 was significantly associated with an increased risk of differentiated thyroid cancer when compared with a lean one, while earlier body shapes were not. The highest risk was observed in women whose body shape increased from lean to large between menarche and adulthood, with a HR of 2.17 (95% CI 1.04-4.53) when compared with women who were lean at both periods. Our study adds to the existing evidence in relation to excess weight to the risk of thyroid cancer, particularly in women whose body shape increased from menarche to adult age.Incidence of differentiated thyroid cancer has increased over the recent decades, raising concerns about a potential influence of the Chernobyl accident. Evidence points to the rising number of surgeries of nodules as the main reason for such an increase. 1 However, environmental factors are also suspected to play a role, as suggested by a large variation in incidence worldwide. 1 Anthropometry is a good candidate as a potential and modifiable risk factor. A meta-analysis of case-control studies concluded that there exists a significant association between weight and height and risk of thyroid cancer but with significant heterogeneity between studies. 2 From 1 pooled analysis of 12 case-control studies and 1 cohort study, the WCRF report concluded to a potential association between thyroid cancer and body size, possibly through changes in iodine requirement. 3 Few prospective studies have investigated the association between anthropometric measurements and risk of differentiated thyroid cancer, and they provided conflicting results. 4,5 A recent metaanalysis of prospective datasets reported sex-specific relative risks, and it estimated from 3 studies a 14% increased risk per 5 kg/m 2 increase in body mass index (BMI) in women. 6 Observed associations between thyroid cancer and height suggest the influence of growth factors or hormones during childhood or adolescence. 3,7 However, there is little data regarding anthropometry during childhood and adolescence and risk of thyroid cancer.Using the data from the Fre...

Obesity Does Not Modify the Risk of Differentiated Thyroid Cancer in a Cytological Series of Thyroid Nodules

“…Although several case-control [7,8,9,10,23,24,25] and cohort prospective studies [11,12,13,14,15,16,17,18,19] have evaluated the association between BMI and thyroid cancer, to our knowledge, this is the first study to investigate this association in a large series of FNAC cytologies. In both the large cytological and the small surgical series, our study does not confirm an association between thyroid cancer and obesity.…”

“…A limitation of the majority of these studies is that the rate of malignancy in obese patients was compared with that of the general population [7,9,10,11,12,13,14,15,18,19]. This methodological approach may have introduced a possible diagnostic bias.…”

“…Several case-control [7,8,9,10] and cohort studies [11,12,13,14,15,16,17,18,19] have reported a positive association between obesity and thyroid cancer [7,8,9,10,11,12,13,14,15,16,17,18,19]. A recent, pooled analysis of 5 prospective studies showed that BMI is positively associated with the risk of thyroid cancer both in men and women, thus providing evidence for obesity as an independent risk factor for thyroid cancer [20].…”

Leptin enhances migration of human papillary thyroid cancer cells through the PI3K/AKT and MEK/ERK signaling pathways

“…A comprehensive systematic review found that an increase of body mass index (BMI) by 5 kg/m 2 was associated with increased risk of thyroid cancer in both men and women with a relative risk of 1.33 and 1.14, respectively (1). Subsequently, the French E3N study including 91,909 women confirmed a significant dose-effect relationship between BMI and thyroid cancer risk (19). At present, the mechanisms for the risk associated between obesity and thyroid cancer are poorly understood.…”

Anthropometric Factors and Thyroid Cancer Risk by Histological Subtype: Pooled Analysis of 22 Prospective Studies

“…However, associations of waist circumference with thyroid cancer risk have been examined in only three studies, with conflicting results (14,15,20). BMI specifically in young adulthood has been associated with an increased risk of thyroid cancer in some studies (6,10,11,15) but not others (8,21). Few studies have evaluated associations for specific histological subtypes apart from papillary carcinoma, which is the least aggressive and increasingly predominant subtype.…”