A longitudinal study of nearly 74,000 US women has found that the woman has already been overweight or obese during his adult life, the greater the risk of developing cancer.
The finding highlights the importance of preventing overweight and obesity at any age, the study authors said.
The main authors of the agency of the World Health Organization International Health Research Caner (IARC) and the University of Calfornia, Irvine, assessed the overweight and obesity duration by body mass index data (BMI) at different time points during the life of the participant. BMI is calculated by dividing weight in kilograms by height in meters squared.
The study, published in the journal Medicine found that overweight for long periods of time is linked to an increased risk of various cancers.
“also noted that, in women after menopause, for some cancers increased risk with increasing duration overweight is ‘more pronounced’ than for others,” said Melina Arnold, lead author study and cancer epidemiologist at the WHO IARC.
“For example, while it was observed that the risk of postmenopausal breast cancer increased by 7% for each last ten years with obesity, this was 23% for endometrial cancer.”
Approximately two thirds of the women in the study were overweight or obese at some point during their adult life. Health outcomes of these women were compared with those who had never been overweight or obese. The researchers took into account other important information on factors related to obesity, such as physical activity, diet, smoking, hormone use, and history of diabetes.
The authors used data collected by the Health Initiative of Women, Americans enrolling postmenopausal women aged between 50 and 79 and followed their health over time.
“we wanted to answer questions like” How important is the number of years they have been obese during their lifetime? “Y” Does the degree of overweight and obesity play a role in this? ‘In epidemiology we call this’ the response rate “or the” impact of cumulative exposure’ dose. “
The study found that the risk of breast cancer after menopause and endometrial cancer related to the duration of overweight were much more pronounced in women who had never used postmenopausal hormones.
excess weight for longer periods of time increases the risk and severity of hypertension, insulin resistance, chronic inflammation, DNA damage and changes in hormone metabolism – the key mechanisms that also increase the risk cancer, she said Dr. Arnold
future research aims to examine whether it matters if you become obese during young adulthood or only later in life and how the duration of obesity affects cancer prognosis, he said.
Dr. Arnold noted that the general conclusions of this study can not be translated directly at the individual level.
“this means that not all women who have had excess weight for some time in your life will develop cancer at some point. The cause of cancer is always multifactorial, which means that both multiple genetic and environmental components could play a role here. Its exact interaction has not yet been explored, “he said.
Professor Ian Olver, Chair of Translational Cancer Research at the University of South Australia, said the findings of study were significant.
“There are many other factors that are associated with cancer, where both the intensity and duration are important. This adds sufficient evidence of the importance of the duration of the independent obesity other risk factors, such as use of hormone replacement in this group, “he said.
” Although the cause can not be deduced from a study of the population and the study should not be used alone to determine management, one of the study’s conclusions is that worth looking further into the control of obesity to reduce the risk of cancers been associated with being overweight or obese. “
Professor Olver said the study used data from BMI calculated from information collected in retrospect, in some cases, the subjective perception of the study participants. This you can allow errors to be introduced, he said.
“in addition, BMI is not the best measure to assess body fat and its association with cancer,” he said.
Tamar Cranswick, Editor, the Conversation
Interview: Ian Olver ,, director of the Institute for Health Research Sansom; Chair of Translational Cancer Research at the University of South Australia
and Melia Ornold, Health and Scientific Cancer Epidemiologist, International Agency for Research on Cancer (IARC)
Courtesy: The conversation