One of the most serious cancers among women is breast cancer. This disease is the first reason for the death of women due to cancer. Increasing breast cancer risk may associate with many factors including genetic, reproductive factors, people's lifestyle, metabolic syndrome (MS) and hormones. MS has been known as a risk factor for prostate, pancreatic, breast and colorectal cancers. The purpose of this review is to identify the relationship between MS components and breast cancer individually. This study was performed by researching electronic database references including PubMed, Google Scholar, CINAHL ProQuest, and web of science through 2019. The effect of MS with its components and breast cancer was reported in many studies.Nevertheless, a thorough understanding of the mechanisms involved remains a challenge.However, one can take several preventive measures, including a proper diet, which is one of the most important determinants of metabolic status. Also, general preventive recommendations are including reducing alcohol consumption, red meat and total fat in the diet. Moreover, increasing the consumption of vegetable and fruit reduce the proportion of MS patients to improve the outcome of breast cancer patients.

Background: Given the increasing prevalence of type 2 diabetes in the community and the use of metformin as one of its most common therapies as well as presence of some evidences on a link between the use of this medicine and vitamin B12 levels, we decided to measure and compare serum level of vitamin B12 among the diabetic patients under treatment by metformin and compare with its natural content. Decreased Vitamin B12 levels leads to some clinical problems including anemia, gastrointestinal disorders (diarrhea, constipation, decreased appetite, etc.,), neurological disorders (tingle, numbness, muscle weakness, etc.,) and mental disorders (memory impairment, depression, behavioral problems, etc.,). Therefore, we would determine if the duration of metformin use and dosage may be effective on serum levels of vitamin B12 among metformin-treated diabetic patients. Methods: Serum vitamin B12 level in metformin-treated type 2 diabetic patients referred to Rasoul-e-Akram Hospital and Specialist Clinic of Taban in Tehran in 2016 (306 subjects selected by convenience sampling) was determined and then compared to its normal level. Results: Of the 306 participants in the study, 120 ones were females (39.2%) and 186 ones were males (60.8%). Also, 150 ones (49%) were healthy and 156 ones (51%) were suffering from diabetes Miletus. There was a significant difference between the type 2 diabetes mellitus and healthy individuals with quantitative variables such as age, height, weight, BMI, serum cholesterol (Chol) level, LDL serum level, HDL serum level, triglyceride (TG) level. The mean blood level of Vitamin B12 level was 448.92±156.75pg/mL among all participants. A Vitamin B12 deficiency frequency of above 6% was seen among diabetic patients. In regression analysis, a model was defined based on which age, gender, diabetes and Metformin used had a significant effect on serum levels of vitamin B-12. Also, none of the variables gender, age, duration of treatment, metformin quantity, weight and BMI was associated with a deficiency of vitamin B12. Conclusion: In the diabetic group, the prevalence of Vitamin B12 deficiency was more than6%. It was also seen that age, gender, diabetes mellitus, metformin intake and metformin content had a significant effect on serum B12 levels. Therefore, measurement of serum levels of vitamin B12 in metformin-treated subjects is recommended.