EFFECTIVENESS OF FLAXSEED IN LOWERING RISK OF BREAST CANCER IN WOMEN: A SYSTEMATIC REVIEW

Abstract

Background: Breast cancer is a cancer that occurs commonly in women. Although pharmacological therapy such as tamoxifen has reduced the incidence of breast cancer, it may induce severe adverse effects. Today, flaxseed is widely studied due to the relation it may have with breast cancer. However, no systematic review has been conducted to find out their effectiveness in preventing breast cancer in healthy women or in treating women with breast cancer. Objectives: This review aims to examine available evidence concerning the effectiveness of flaxseed in lowering breast cancer-related biomarkers in healthy women and in women with breast cancer or breast cancer remission, as compared to placebo or usual care (tamoxifen). Methods: A search in the six electronic databases was performed from inception to 01 January 2021 to identify English-language research studies without any limitation on year published. The risk of bias tool, ROBINS-I tool and JBI critical appraisal checklist were used to assess the quality of individual studies. The overall evidence was evaluated using GRADE approach. Results: Amongst the 724 records retrieved, nine were RCTs, two were quasi-experimental studies and two were case-control studies. All the RCTs had unclear risk of bias and both the quasi-experimental studies had a moderate risk of bias. Narrative synthesis showed that flaxseed has different effects on different markers of breast cancer risk. According to the GRADE criteria, a very low overall quality of evidence was yielded, with the exception of a high quality of evidence for an outcome that emerged from the two case-control studies. Conclusions: This suggests that flaxseed may potentially be effective in preventing and treating breast cancer and should be further researched on with more well-designed RCTs using larger sample size to develop a more robust evidence.