Somatotype and risk of breast cancer: a case-control study in Uruguay Somatotipo de risco de câncer de mama: um estudo caso-controle no Uruguai
According to the evidence, there is a need for more thorough assessment and quantification of body size and shape and the risk of breast cancer. Using the somatotype methodology, we carried out an original research in order to explorepossible associations between body shape and the risk of breast cancer in Uruguayan women. With this objective, 254 recent breast cancer cases and 1,000 frequency-matched healthy controls were interviewed on menstrual and reproductive story, and a series of skinfolds, circumferences and diameters were measured specifically to calculate somatotype. A positive association with breast cancer was found forhigh endomorphy (Odds Ratio [OR] = 2.82, p < 0.001), mainly among premenopausal women (OR = 4.98, p =45) menstruations had ceased at least for 6 months, excluding pregnancy, she was classified as postmenopausal; • History of cancer in first and second degree relatives; • Physical exercise (yes/no), frequency, duration and intensity and • Self-reported weight at age 18. There was noquestion on hormonal replacement therapy, because it is not usually prescribed to postmenopausal women who belong to the studied subpopulation. The question about physical exercise referred to free-time activity, recreational or competitive, 5 years prior the interview. This assessment was performed only as an exploratory tool in the studied group, whose low income limits their time and access tosport institutions. The method was not validated. Concerning anthropometry, the following measurements were taken:
Rev Bras Epidemiol 2008; 11(2): 215-27
218 Ronco, A.L. et al.
Somatotype and risk of breast cancer: a case-control study in Uruguay
• height (measured to the nearest centimeter) • weight (at intervals of 0.100 kg) • circumferences (in cm): (waist, hip, flexedand tensed arm, calf ) • skinfolds (in mm): tricipital, subscapular, supraspinal, calf ) • diameters (in mm): bicondyleal (femur) and bicondyleal (humerus). Anthropometric equipment included a height scale and headboard, a weighing scale, a Vernier caliper, a flexible plastic measuring tape, and a skinfold caliper. The same mechanical scale was used along the whole study period, with a weeklycalibration. Subjects were weighed wearing minimal clothing. For body measurements a plastic measuring tape at intervals of 0.5 cm (for circumferences), a Vernier caliper (for diameters) and a FatTrack Pro ® (Accufitness, Greenwood Village, CO, USA) digital caliper (for skinfolds) were used. Regarding these latter, if two consecutive measurements were similar, the value obtained was registered asvalid. If both were different, a third one was taken and the median value was then registered. Measurements were performed according to Carter’s Instruction Manual33. Somatotype
into account: height, weight, four skinfolds (triceps, subscapular, supraspinal, and medial calf), two circumferences (tensed arm, calf ), and two bone breadths (humerus, femur). Mean values of somatotype werecalculated for all cases and all controls. Formulas applied to calculate somatotype are the following: Endomorphy = - 0.7182 + 0.1451 (Σ) - 0.00068 (Σ 2) + 0.0000014 (Σ 3) Mesomorphy = (0.858 HB + 0.601 FB +0.188 CAG + 0.161 CCG) - (0.131 H) + 4.5 Ectomorphy: If HWR ≥ 40.75, then Ectomorphy = 0.732 HWR - 28.58 If HWR < 40.75 and > 38.25, then Ectomorphy = 0.463 HWR - 17.63 If HWR ≤ 38.25, then Ectomorphy =0.1 where: Σ = (sum of triceps, subscapular and supraspinale skinfolds) multiplied by (170.18/height in cm); HB = humerus breadth; FB = femur breadth; CAG = corrected arm girth; CCG = corrected calf girth; H = height; HWR = height / cube root of weight. CAG and CCG are the girths corrected for the triceps or calf skinfolds respectively as follows: CAG = flexed arm girth - triceps skinfold/10;...
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