Weight change since age 20 and incident risk of obesity‐related cancer in Japan: a pooled analysis of the Miyagi Cohort Study and the Ohsaki Cohort Study

Abstract

It is unclear whether weight change during adulthood affects the risk of obesity-related cancers such as those of the esophagus, colorectum, pancreas, breast, endometrium, and kidney among Japanese, where obesity is less frequent and less severe. We examined the association between weight change during adulthood and the risk of obesity-related cancer among Japanese by conducting a pooled analysis of two prospective studies of residents in Miyagi Prefecture, Japan. A total of 78,743 persons (40,422 women and 38,321 men) aged 40-79 years participated in the Miyagi Cohort Study in 1990 and in the Ohsaki Cohort Study in 1994. Weight change since age 20 was divided into four categories (weight loss; stable weight; moderate weight gain; high weight gain). Cox proportional hazards regression analysis was used to estimate the multivariate hazard ratios (HRs) and 95% confidence intervals (CIs) for obesity-related cancer incidence. During 1,057,899 person-years of follow up, 4,467 cases of obesity-related cancer (women; 1,916 cases, men; 2,551cases) were identified. In women, compared to the stable weight, weight gain was associated with an increased risk of obesity-related cancer (moderate weight gain; HRs = 1.10, 95%CIs: 0.97-1.26, high weight gain; HRs = 1.29, 95%CIs: 1.14-1.47). The results indicate that weight gain since age 20 was associated with a significantly increased risk of obesity-related cancer among Japanese women. By contrast, in men, our study found that weight change is not associated with the incidence of obesity-related cancer.

Body weight variability and cancer incidence in men aged 40 years and older-Korean National Insurance Service Cohort

“…Many studies have been conducted on weight and cancer risk or weight gain and obesity-related cancer risk, whereas several studies have examined the association between BWV and cancer 11 , 13 , 20 – 24 . Most previous studies showing a positive association between weight cycling or fluctuation and cancer risk were conducted in women 11 , 13 , 20 – 26 , especially in obesity-related cancers such as breast cancer, endometrial cancer, and renal cancer 25 , 26 . Meanwhile, a few studies in men showed a null association between weight change or cycling and cancer incidence, including prostate cancer 5 , 27 .…”

Levels of Physical Fitness and Weight Status in Children and Adolescents: A Comparison between China and Japan

“…Existing evidence suggests that physical fitness in childhood and adolescence is associated with total and abdominal adiposity, cardiovascular disease risk factors, skeletal health, psychological symptoms, and even academic performance [ 9 ]. In recent decades, a decline in physical fitness [ 10 , 11 ] and increased prevalence of overweight and obesity [ 12 , 13 ] are well documented in both China and Japan. According to a joint survey conducted by the two countries in 2016, the prevalence of overweight and obesity was 17.5% and 5.8% higher in China than in Japan among boys and girls [ 14 ].…”

Preventable fractions of cancer incidence attributable to 7-years weight gain in the Norwegian Women and Cancer (NOWAC) study

“…Still, WCRF suggests that weight gain is associated with pancreatic cancer, but only as an interrelated aspect with other anthropometrics of body fatness. In addition, two recent studies on weight change and pancreatic cancer also reported null associations 9 , 10 . There are some plausible explanations to why we found a strong association between weight gain and pancreatic cancer, contrary to that of the literature.…”

“…However, weight gain tends to capture increases in fat mass more precisely than BMI and is based on at least two repeated measurements and therefore less prone to misclassification 5 . Adults tend to follow upward weight trajectories 6 and weight gain has been shown to be independently associated with several cancers [7][8][9][10] . Weight change and cancer studies most commonly assess long-term weight change from recalled age at 18 to enrolment, with various designs in relation to sample size, exposure treatment, and follow-up duration.…”