The new research finds that adults with persistent metabolic syndrome that worsens over time are at increased risk for any type of cancer.
The conditions that make up metabolic syndrome (high blood pressure, high blood sugar, increased abdominal adiposity, and high cholesterol and triglycerides) have been associated with an increased risk of diseases, including heart disease, stroke, and type 2 diabetes, wrote Li Deng, PhD, of Capital Medical University, Beijing, and colleagues.
However, a single assessment of metabolic syndrome at one point in time is inadequate to show an association with cancer risk over time, they said. In the current study, the researchers used models to examine the association between trajectory patterns of metabolic syndrome over time and the risk of overall and specific cancer types. They also examined the impact of chronic inflammation concurrent with metabolic syndrome.
What We Know About Metabolic Syndrome and Cancer Risk
A systematic review and meta-analysis published in Diabetes Care in 2012 showed an association between the presence of metabolic syndrome and an increased risk of various cancers including liver, bladder, pancreatic, breast, and colorectal.
More recently, a 2020 study published in Diabetes showed evidence of increased risk for certain cancers (pancreatic, kidney, uterine, cervical) but no increased risk for cancer overall.
In addition, a 2022 study by some of the current study researchers of the same Chinese cohort focused on the role of inflammation in combination with metabolic syndrome on colorectal cancer specifically, and found an increased risk for cancer when both metabolic syndrome and inflammation were present.
However, the reasons for this association between metabolic syndrome and cancer remain unclear, and the effect of the fluctuating nature of metabolic syndrome over time on long-term cancer risk has not been explored, the researchers wrote.
“There is emerging evidence that even normal weight individuals who are metabolically unhealthy may be at an elevated cancer risk, and we need better metrics to define the underlying metabolic dysfunction in obesity,” Sheetal Hardikar, MBBS, PhD, MPH, an investigator at the Huntsman Cancer Institute, University of Utah, said in an interview.
Dr. Hardikar, who serves as assistant professor in the department of population health sciences at the University of Utah, was not involved in the current study. She and her colleagues published a research paper on data from the National Health and Nutrition Examination Survey in 2023 that showed an increased risk of obesity-related cancer.
What New Study Adds to Related Research
Previous studies have consistently reported an approximately 30% increased risk of cancer with metabolic syndrome, Dr. Hardikar said. “What is unique about this study is the examination of metabolic syndrome trajectories over four years, and not just the presence of metabolic syndrome at one point in time,” she said.
In the new study, published in Cancer on March 11 (doi: 10.1002/cncr.35235), 44,115 adults in China were separated into four trajectories based on metabolic syndrome scores for the period from 2006 to 2010. The scores were based on clinical evidence of metabolic syndrome, defined using the International Diabetes Federation criteria of central obesity and the presence of at least two other factors including increased triglycerides, decreased HDL cholesterol, high blood pressure (or treatment for previously diagnosed hypertension), and increased fasting plasma glucose (or previous diagnosis of type 2 diabetes).
The average age of the participants was 49 years; the mean body mass index ranged from approximately 22 kg/m2 in the low-stable group to approximately 28 kg/m2 in the elevated-increasing group.
The four trajectories of metabolic syndrome were low-stable (10.56% of participants), moderate-low (40.84%), moderate-high (41.46%), and elevated-increasing (7.14%), based on trends from the individuals’ initial physical exams on entering the study.
Over a median follow-up period of 9.4 years (from 2010 to 2021), 2,271 cancer diagnoses were reported in the study population. Those with an elevated-increasing metabolic syndrome trajectory had 1.3 times the risk of any cancer compared with those in the low-stable group. Risk for breast cancer, endometrial cancer, kidney cancer, colorectal cancer, and liver cancer in the highest trajectory group were 2.1, 3.3, 4.5, 2.5, and 1.6 times higher, respectively, compared to the lowest group. The increased risk in the elevated-trajectory group for all cancer types persisted when the low-stable, moderate-low, and moderate-high trajectory pattern groups were combined.
The researchers also examined the impact of chronic inflammation and found that individuals with persistently high metabolic syndrome scores and concurrent chronic inflammation had the highest risks of breast, endometrial, colon, and liver cancer. However, individuals with persistently high metabolic syndrome scores and no concurrent chronic inflammation had the highest risk of kidney cancer.