A Pilot Study Comparing the Effect of Flaxseed, Aromatase Inhibitor, and the Combination on Breast Tumor Biomarkers

Abstract

Use of complementary approaches is common among breast cancer survivors. Potential interactions between aromatase inhibitors (AI) and high phytoestrogen foods, such as flaxseed (FS) are not often described. We conducted a pilot 2×2 factorial, randomized intervention study between tumor biopsy and resection, in 24 postmenopausal women with estrogen receptor positive (ER+) breast cancer, to assess the effects of flaxseed and anastrozole, and possible interactions between them, on serum steroid hormone and tumor-related characteristics associated with long-term survival (Roswell Park Cancer Institute, 2007–2010). The effect of each treatment vs placebo on outcomes was determined by linear regression adjusting for pre-treatment measure, stage, and grade. Although not statistically significant, mean ERβ expression was approximately 40% lower from pre- to post-intervention in the FS+AI group only. We observed a statistically significant negative association (β±SE −0.3±0.1; p=0.03) for androstenedione in the FS+AI group vs placebo and for DHEA with AI treatment (β±SE −1.6±0.6; p=0.009). Enterolactone excretion was much lower in the FS+AI group compared to the FS group. Our results do not support strong effects of flaxseed on AI activity for selected breast tumor characteristics or serum steroid hormone levels, but suggest AI therapy might reduce the production of circulating mammalian lignans from flaxseed.

The Effect of Flaxseed in Breast Cancer: A Literature Review

“…These women were then divided randomly into four groups: Group 1 with 25 g/daily of ground flaxseed and 1 placebo pill daily; Group 2 with 1 mg/daily of anastrozole; Group 3 with 25 g/daily of ground flaxseed and 1 mg/daily of anastrozole; and Group 4 with 1 placebo pill daily. This study did not show any effects regarding flaxseed on the aromatase inhibitor activity in selected breast tumor characteristics and serum steroid hormone levels ( 9 ). Further studies are needed to support a possible interaction between flaxseed intake and the aromatase inhibitor––anastrozole.…”

“…Although they are defined as one of the richest plant sources in omega-3 fatty acids, these seeds are also characterized by their lignan content. Although lignans are found in a variety of vegetable sources, such as whole grains, sesame seeds, vegetables, and fruits, flaxseeds have approximately 100 times more lignans than other foods ( 9 , 17 , 18 ).…”

“…These are structurally similar to estrogen, and have antioxidant activity and a weak estrogenic action (Figure 1 ). It also works as an antiestrogenic because its structure is very similar to the main form of estrogen, which allows its binding to the cell’s receptors, thus inhibiting the growth of cancer cells ( 9 , 20 – 23 ).…”

“…Many people with cancer choose to make some changes in their eating habits while subjected to conventional, like chemotherapy. The patients do this in the hopes of decreasing the treatment’s severe side effects such as anxiety, depression, insomnia, headaches, nausea, and vomiting (among others) ( 6 – 9 ).…”

Phytotherapy and Nutritional Supplements on Breast Cancer

“…However, these recommendations should be confirmed through clinical trials. The use of flaxseed and aromatase inhibitor (using anastrozole as model drug) was also studied by MaCann and collaborators using biopsy and resection samples from postmenopausal women with oestrogen receptor-positive breast cancer [ 62 ]. Nevertheless, the results did not support strong effects on aromatase inhibitor activity but suggested that anastrozole might reduce the beneficial effects of flaxseed.…”