Background:According to some studies, the metabolic syndrome causes diverse primary cancers; however, there is no evidence about metabolic syndrome impact on second cancers development in women.Aim:To find out the implication of the modified metabolic syndrome in women with second cancers.Materials and Methods:This was a case–control study, at a general hospital in Mexico City, in women with second cancers (cases) and age-matched women with only one neoplasm (controls). The analysis comprised: Tumor (s), anthropometric features, and body mass index (BMI); moreover, presence of diabetes mellitus, hypertension, and fasting serum levels of total cholesterol, triglycerides and glucose.Results:The sample was of nine cases and 27 controls. In cases, the metabolic syndrome (diabetes mellitus or glucose > 99 mg/dL + hypertension or blood pressure ≥ 135/85 mm Hg + triglycerides > 149 mg/dL or BMI ≥ 30 kg/m2) was more frequent (odds ratio 20.8, 95% confidence interval: 1.9–227.1).Conclusion:Our results suggest that in women, the modified metabolic syndrome may be a risk factor for second cancers.