Unintentional weight loss associated with increased risk of cancer
Recent and unintentional weight loss is associated with an increased risk of a cancer diagnosis in the coming year, according to a new study in JAMA. Researchers from Karolinska Institutet and others behind the study urge healthcare professionals and the public to be vigilant about sudden and unintentional weight loss.
"If you lose weight without making changes to your diet and exercise routine, you should see a doctor to find out what the cause may be. There are several conditions that can result in unexpected weight loss. Doctors can evaluate whether it is something that needs further investigation," says Qiaoli Wang, a researcher at the Department of Clinical Science, Intervention and Technology, Karolinska Institutet, and the study's first author.
The new study included 157 474 people aged 40 and older in the United States. They were followed for more than 30 years. Detailed information on weight and exercise was collected every two years and dietary data was reported every four years. The researchers assessed weight loss-promoting behaviors by evaluating changes in participants' diet and exercise.
Weight loss intentionality was classified as 'high' for those who had increased their physical activity and improved their diet, 'medium' if only one of the factors had changed, and 'low' if no changes had been made to the diet and exercise. In the latter group, the incidence of cancer in the coming year was twice as high in people who lost more than 10% of their body weight during the past two years compared to those who did not lose weight.
'We found that the risk was particularly elevated for upper gastrointestinal cancer, hematological cancer, colorectal cancer and lung cancer, but not for breast cancer, urinary tract cancer, brain cancer or melanoma,' says Qiaoli Wang.
Should see a doctor for examinations
The study suggests that people who have recently lost weight, especially those with unintentional weight loss, should see their doctor for further examinations to rule out possible cancers. Unintentional weight loss is important for healthcare providers to consider when assessing individual cancer risk.
"Intentional weight loss through more exercise or a healthier diet can be good for people's health. But unintentional weight loss that is not due to healthier behaviors may indicate an underlying disease, including cancer," said Qiaoli Wang.
The study was mainly funded by the National Institutes of Health (USA) and the Swedish Research Council and the Bob Parsons Fund. The researchers declare that there are no conflicts of interest.
"Cancer Diagnoses After Recent Weight Loss", Qiao-Li Wang, Ana Babic, Michael H. Rosenthal, Alice A. Lee, Yin Zhang, Xuehong Zhang, Mingyang Song, Leandro F. M. Rezende, Dong Hoon Lee, Leah Biller, Kimmie Marios Giannakis, Andrew T. Chan, Jeffrey A. Meyerhardt, Charles S. Fuchs, A. Heather Eliassen, Brenda M. Birmann, Meir J. Stampfer, Edward L. Giovannucci, Peter Kraft, Jonathan A. Nowak, Chen Yuan, Brian M. Wolpin, JAMA, online January 23, 2024, doi: 10.1001/jama.2023.25869