Results from case-control and prospective studies suggest a moderate positive association between obesity and height and differentiated thyroid carcinoma (TC). Little is known on the relationship between other measures of adiposity and differentiated TC risk. Here, we present the results of a study on body size and risk of differentiated TC based on a large European prospective study (EPIC). During follow-up, 508 incident cases of differentiated TC were identified in women, and 58 in men. 78% of cases were papillary TC. Cox proportional hazard models were used to estimate hazard ratios (HRs). In women, differentiated TC risk was significantly associated with body mass index (BMI, kg/m 2 ) (HR highest vs lowest quintile 5 1.41, 95% CI: 1.03-1.94); height (HR 5 1.61; 95% CI: 1.18-2.20); HR highest vs lowest tertile waist (HR 5 1.34, 95% CI: 1.00-1.79) and waist-to-hip ratio (HR 5 1.42, 95% CI: 1.05-1.91). The association with BMI was somewhat stronger in women below age 50. Corresponding associations for papillary TC were similar to those for all differentiated TC. In men the only body size factors significantly associated with differentiated TC were height (non linear), and leg length (HR highest vs. lowest tertile 5 3.03, 95% CI: 1.30-7.07). Our study lends further support to the presence of a moderate positive association between differentiated TC risk and overweight and obesity in women. The risk increase among taller individuals of both sexes suggests that some genetic characteristics or early environmental exposures may also be implicated in the etiology of differentiated TC.

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...

Although earlier studies have indicated an inverse association between corpulence during childhood and the risk for breast cancer in adulthood, no study had evaluated body shape at different ages or body shape evolution in relation to the risk for breast cancer defined by menopausal status and hormone receptor status. Hazard ratios (HR) were estimated using multivariate Cox models in 81,089 women from the French E3N cohort to evaluate the risk for breast cancer associated with body shape (Sørensen's scale) at ages 8, menarche, 20-25, and 35-40 years. Six lifetime body shape trajectories were also estimated according to Nagin's approach to group-based trajectory modeling, and were analyzed in relation to the risk for breast cancer. During follow-up, 3573 breast cancer cases were diagnosed. At age 8 and at menarche, an increasing size of the body was associated with a significantly negative risk for estrogen receptor (ER)+/progesterone receptor (PR)+ postmenopausal breast cancer [both had a P(trend)=0.001; HR=0.80 (0.67-0.94) and HR=0.74 (0.64-0.86), respectively], for the largest body shapes compared with the first body shape. No significant association with body shape was found at the other ages. In terms of body shape evolution throughout life, women with a large body shape at menarche, irrespective of their body shape before or after menarche, tended to have a decreased risk for ER+/PR+ postmenopausal breast cancer compared with women who were constantly lean. Adjustment for current BMI or age at menarche did not modify any associations. Our study found an inverse association between adiposity at menarche and the risk for ER+/PR+ postmenopausal breast cancer, independent of corpulence at other ages. This work should encourage longitudinal studies with hormonal information to examine the underlying biological mechanisms.

Objective: We evaluated the relationship between hip and waist circumferences (HCs, WCs), waist-to-hip ratio, height, weight and body mass index (BMI) and breast cancer risk according to menopausal status of women and cancer hormone receptor status. Design: We used data from the French E3N longitudinal prospective cohort. Subjects: In the total population of 63 726 women who were analyzed, 1887 breast cancer cases were diagnosed during follow-up. Results: Among postmenopausal women, the risk of ER þ /PR þ breast cancer increased with increasing weight, BMI, and both HCs and WCs, although these two associations disappeared after adjustment for BMI. No association was seen with ERÀ/PRÀ breast cancers. Among premenopausal women, among the different factors studied, HC only (no association was observed for any of the different factors studied except for HC) was associated with an increased risk of ER þ /PR þ breast cancer after adjustment for BMI (hazard ratio (HR) ¼ 1.65; (1.04-2.62) when comparing the highest to lowest tertile; P-trend across tertiles ¼ 0.03) and of ERÀ/PRÀ breast cancer both before and after adjustment for BMI (HR ¼ 2.85 (1.33-6.13); P-trend o0.01, and HR ¼ 3.13 (1.19-8.27) P-trend ¼ 0.02, respectively). In the latter group, the association with HC was observed whatever the WC (HR ¼ 2.81 (1.18-6.70) and HR ¼ 2.79 (1.16-6.76) in women with high HC/low WC and high HC/high WC, respectively). Conclusion: The increase in risk of premenopausal breast cancer associated with large HC for both ER þ /PR þ and ERÀ/PRÀ subtypes may provide insight into a specific risk factor for premenopausal breast cancer.

Background: Physical activity probably protects against the risk of breast cancer after menopause, but questions remain about how rapidly and for how long this protective effect exists.Methods: We analyzed data from 59,308 postmenopausal women (2,155 incident invasive breast cancers) followed between 1993 and 2005 (8.5 years postmenopause on average) through biennial questionnaires. Multivariable Cox models included time-varying exposure data, using levels of recreational physical activity self-reported in 1993, 1997, and 2002.Results: Women with recent (within the previous 4 years) recreational physical activity levels !12 metabolic equivalent task-hours (MET-h)/week had a lower risk of invasive breast cancer than women with lower levels [HR, 0.90; 95% confidence interval (CI), 0.82-0.99], with no apparent dose-response relation beyond 12 MET-h/ week. Associations did not vary significantly across ER/PR subtypes. Risk reductions were of the same magnitude order regardless of weight change, body mass index, waist circumference, or less recent (5-9 years earlier) physical activity levels. Among women with levels of physical activity !12 MET-h/week 5 to 9 years earlier, those who became less active (<12 MET-h/week) had a significantly increased risk of breast cancer compared with those who did not (HR, 1.16; 95% CI, 1.01-1.35). And, compared with the least active women at both time points, they had no significantly decreased risk of breast cancer (HR, 1.06; 95% CI, 0.87-1.29).Conclusions: Our results suggest a decrease in risk associated with recent recreational physical activity even of modest levels.Impact: Starting or maintaining physical activity after menopause may be beneficial regarding breast cancer risk. Cancer Epidemiol Biomarkers Prev; 23(9); 1893-902. Ó2014 AACR.