The conditions that comprise 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, China, and colleagues.
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 2019 study published in Diabetes showed evidence of increased risk for certain cancers (pancreatic, kidney, uterine, cervical) but no increased risk for cancer overall.
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.
What Does New Study Add to Other Research on Metabolic Syndrome and Cancer Risk?
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 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.
What Are the Limitations of This Research?
The researchers of the current study acknowledged the lack of information on other causes of cancer, including dietary habits, hepatitis C infection, and Helicobacter pylori infection. Other limitations include the focus only on individuals from a single community of mainly middle-aged men in China that may not generalize to other populations.
Also, the metabolic syndrome trajectories did not change much over time, which may be related to the short 4-year study period.
What Is the Takeaway Message for Clinical Practice?
The results suggest that monitoring and managing metabolic syndrome could help reduce cancer risk, the researchers concluded.
“This research suggests that proactive and continuous management of metabolic syndrome may serve as an essential strategy in preventing cancer,” senior author Han-Ping Shi, MD, PhD, of Capital Medical University in Beijing, said in a press release accompanying the study.
More research is needed to assess the impact of these interventions on cancer risk, he noted. However, the data from the current study can guide future research that may lead to more targeted treatments and more effective preventive strategies, he said in a statement.
The study was supported by the National Key Research and Development Program of China. The researchers had no financial conflicts to disclose.