A newly published study has reported that flaxseed oil enhances the effectiveness of Herceptin in reducing tumor growth in a mouse model of HER2+ breast cancer. Herceptin is used for breast cancer that overexpresses human epidermal growth factor receptor 2 (HER2). However, tumors typically eventually develop resistance to Herceptin. Flaxseed oil, which is rich in the omega-3 fatty acid alpha-linolenic acid, has been shown to reduce HER2 expression and signaling in estrogen receptor positive (ER+) breast cancer.

In the study, mice had their ovaries removed, HER2 overexpressing tumors were established in the mice, and estrogen pellet implants were administered to promote tumor growth. The mice were then divided into groups which were administered either Herceptin (2.5 or 5 mg/kg body weight) or no Herceptin and given either a basal diet or the basal diet plus dietary flaxseed oil. Weekly measurements were taken of palpable tumor area.

Tumors in the untreated mice grew 187% whereas tumors of mice treated with 2.5 mg/kg Herceptin did not change in size. On the other hand, tumors of mice treated with 5 mg/kg Herceptin were found to shrink by 75% after four weeks of treatment, tumors of mice treated with flaxseed oil plus 2.5 mg/kg Herceptin shrank 89%, and tumors of mice treated with flaxseed oil plus 5 mg/kg Herceptin shrank 84%. Flaxseed oil plus 2.5 mg/kg Herceptin was found to result in significantly lower tumor cell proliferation and higher cell death compared to 2.5 mg/kg Herceptin treatment alone, and had an effect similar to that of 5 mg/kg Herceptin treatment with or without flaxseed oil. The authors conclude that flaxseed oil enhanced Herceptin's tumor-reducing effects. Furthermore, the combination of flaxseed oil and low dose Herceptin was as effective as high dose Herceptin treatment in the mice.

Please see our article on how to optimize your breast cancer diet for information on what to eat during all stages of treatment and recovery.