Higher risk of gynecological cancers in women with metabolic syndrome, a meta-analysis suggests
A systematic review and meta-analysis found that women with metabolic syndrome are at an increased risk of gynaecological cancers, regardless of the study design, type of gynaecological cancers, and definition of metabolic syndrome
Metabolic syndrome is a multifactorial disorder comprising of obesity, hyperglycaemia, hypertension, high triglycerides, and low high-density lipoprotein cholesterol. The co-occurrence of these metabolic abnormalities increases the risk of cardiovascular diseases, type 2 diabetes and cancers.
A recent systematic review and meta-analysis published with the Indian Journal of Medical Research (IJMR), which included 25 studies (four cross-sectional, eight case-control, and 13 cohort studies), concluded that women with metabolic syndrome are at an increased risk of gynaecological cancers, regardless of the study design, type of gynaecological cancers, and definition of metabolic syndrome.
Association of uterine/endometrial cancer with metabolic syndrome
Women in studies who had uterine/endometrial conditions were about twice as likely to be exposed to the risk compared to those without the condition, and similar results were seen in other types of studies. This means that having the risk factor increased the likelihood of someone experiencing the outcome being studied, and this finding was consistent across different kinds of study designs.
Association of ovarian cancer with metabolic syndrome
Women with ovarian cancer and metabolic syndrome were about three times more likely to have certain risk factors in case-control studies, but in other types of studies, such as cohort studies, having metabolic syndrome did not seem to make much difference to their risk. This means that the link between metabolic syndrome and ovarian cancer risk is still uncertain and varies depending on how the research has been conducted.
Association of cervical cancer, vaginal/vulvar cancer with metabolic syndrome
Women with metabolic syndrome are at 25% higher risk of developing cervical cancer compared with women without metabolic syndrome, based on studies that followed groups of women over time. This means metabolic syndrome makes it more likely for women to get cervical cancer, even when taking into account other health factors. In the case of vaginal or vulvar cancer, women with metabolic syndrome have about 50% higher risk compared with women without the syndrome, based on one study.
Risk of bias, quality of evidence
The risk of bias, as assessed using critical appraisal checklists, revealed a low risk of bias for all studies. However, the quality of evidence using the GRADE (Grading of Recommendations, Assessment, Development and Evaluation) framework indicated very low-quality evidence for all included studies. In the GRADE assessments, the quality of study design and imprecision parameters were not serious, but parameters for inconsistency and indirectness had serious concerns.
A closer look at the meta-analysis results reveals that risk is markedly higher in ovarian cancer compared to endometrial cancer, as per pooled odds ratio results from the case-control studies. However, the pooled hazards ratio from cohort studies depicts a higher risk of uterine/endometrial cancer compared to ovarian and cervical cancer.
There is significant heterogeneity across all studies, so caution is necessary when interpreting the pooled estimates. Differences in diagnostic criteria for metabolic syndrome and the absence of individual patient data limited the ability to conduct a detailed meta-regression analysis. Additionally, due to the limited number of studies for each gynaecological cancer, meta-regression, publication bias, and subgroup analyses could not be carried out.
Regarding India, 54 studies were screened for inclusion. Of these, 31 were excluded because they did not focus on women with metabolic syndrome, and 20 were unrelated to cancer. One study on oral cancer, a non-gynaecological cancer, was also excluded. Additionally, three studies included fewer than three components of metabolic syndrome and could not be diagnosed with it based on standard definitions, leading to their exclusion.
Based on these findings, we recommend that managing metabolic syndrome should be a key component in preventing and treating gynaecological cancers in India. Additionally, primary prevention and early detection are crucial for women with fully developed conditions like diabetes.
