Body weight is considered a risk factor for cancer — but can losing it reverse that risk?
The results came from a long-term study of more than 30,000 Cleveland Clinic patients between 2004 and 2017. The patients all had a body mass index of 35 or greater — considered “class 2,” or “moderate risk” obesity by medical professionals.
Researchers followed up with about 5,000 patients between ages 18 and 80 who had gastric bypass or gastric sleeve surgery during the study period. None of the people studied had been previously diagnosed with cancer.
And their chances of developing, or dying of, obesity-linked cancers such as ovarian and pancreatic cancer were significantly lower. During the study, 2.9 percent of patients who had surgery developed cancer, compared with 4.9 percent of their counterparts; 0.8 percent died, compared with 1.4 percent of nonsurgical patients. The effects were seen across the board and appeared to be independent of age, sex or race.
According to the Centers for Disease Control and Prevention, more than 1.7 million new cancer cases were reported in 2019 alone. Additionally, nearly 42 percent of U.S. adults had obesity as of March 2020.
“Given the growing epidemic of obesity, obesity-associated cancers are a major public health concern,” says Ali Aminian, director of the Cleveland Clinic’s Bariatric and Metabolic Institute and the study’s lead author. “If we help patients to lose weight, we can significantly mitigate that risk.”
Bariatric surgery has gained steam as an obesity treatment in recent years, with an estimated 256,000 such procedures performed in the United States in 2019, according to an industry group. The researchers said “substantial weight loss” was required to reduce cancer risk.
Other factors might be at play — it’s unclear whether the surgical patients made healthier lifestyle choices or the nonsurgical patients were hesitant to participate in cancer screenings. Few of the patients were not Black or White, indicating a need for further research.