Measured adolescent body mass index and adult breast cancer in a cohort of 951,480 women

Abstract

Body mass index (BMI) in adolescence, studied predominantly as a self-reported risk factor for breast cancer (BC), may have been subjected to recall bias. We examined the association between measured BMI in adolescence and the incidence of BC by menopausal status. 951,480 Jewish Israeli females aged 16-19 who underwent anthropometric measurements in 1967-2011 were followed up to 31.12.2012 for BC incidence. Cox proportional hazards models assessed the association between adolescent BMI (as age-specific CDC percentiles) and time to BC diagnosis, adjusting for sociodemographic covariates. The analysis was also subdivided by age at diagnosis. 9619 BC cases diagnosed during 18,078,941 person-years of follow-up were included in multivariable analyses: 4901 premenopausal, 3809 perimenopausal, and 909 postmenopausal. Compared with 'healthy' BMI (5th-<85th percentiles) and adjusted for country of origin, education, and height, adolescent BMI was largely negatively associated with BC: hazard ratio (HR) = 1.057 (95 % confidence interval (CI) 0.955-1.169, p = 0.286) in underweight (<5th percentile); HR = 0.918 (95 % CI 0.849-0.993, p = 0.032) in overweight (85th-<95th percentiles); and HR = 0.682 (95 % CI 0.552-0.843, p = 0.00004) in obese (≥95th percentile) women. In premenopausal, but not peri- and postmenopausal BC, associations were statistically significant; underweight was associated with increased risk of premenopausal BC (HR = 1.15, 95 % CI 1.01-1.31, p = 0.037), and overweight and obesity with significantly lower risk. Adolescent thinness was associated with increased risk for early BC. Overweight and obesity were protectively associated with premenopausal but not postmenopausal BC. The lack of an association of adolescent overweight/obesity with increased peri- and postmenopausal BC suggests a causal role for adult weight gain.

Body fatness at a young age, body fatness gain and risk of breast cancer: systematic review and meta‐analysis of cohort studies

“…A nested case–control study that used the data from the Nurses' Health Study and the Nurses' Health Study II was further excluded; instead, we included two studies from the same populations that further reported risk estimates by menopausal status. Finally, 24 publications were eligible for inclusion in the final analysis.…”

“…Twenty‐four studies were included in this meta‐analysis, which assessed body fatness at a young age and the risk of breast cancer. In the meta‐analysis of combined premenopausal and postmenopausal women, the summary RR for each 5 kg m −2 increase in BMI was 0.86 (95% CI 0.82, 0.90) (Fig.…”

“…Although the association between adult body fatness and the risk of breast cancer has yielded convincing evidence of the potential detrimental role of excess body fatness in the development of breast cancer after menopause, the association between young age (≤30 years [including childhood, adolescence and young adulthood]) body fatness (measured by BMI) and the risk of breast cancer has been less defined. Thus far, a large number of studies have been conducted to investigate the association between body fatness at a young age and the risk of breast cancer later in life ; most, but not all, studies found an inverse association with the risk of breast cancer later in life. According to the latest findings from continuing update projects conducted by the World Cancer Research Fund and the American Institute for Cancer Research, the panel judged young adulthood body fatness as a probable protective factor for breast cancer .…”

Adolescent obesity and adult male breast cancer in a cohort of 1,382,093 men

“…In FBC, however, the relationship with adolescent BMI is inverse for premenopausal events . The reason may be the negative feedback on the hypothalamic‐pituitary axis caused by the high basal levels of circulating ovary‐produced estradiol in addition to the peripheral fat tissue synthesized hormones.…”

“…Unfortunately, we had no data to test this hypothesis. In women, SES and education were positively associated with FBC . A 1997 IARC publication focusing on social inequalities and cancer stated that while differences in cancer incidence are seen within industrialized countries by SES, the evidence is very limited as to which socioeconomic factors are of most importance, or whether it is the overall “package” of social inequality that mostly matters…”