Lignans are accessible to human breast cancer xenografts in athymic mice

Lignan-rich diet has been linked with reduced breast cancer risk, and experimental studies have supported the hypothesis of lignans as cancer growth inhibiting compounds. However, it has not been clear if these compounds are accessible in the mammary tumor tissue in vivo. In this study, the accessibility and accumulation of lignans to breast cancer tissue was determined after oral administration of tritium labeled dietary lignan secoisolariciresinol diglucoside (3H-SDG) to athymic mice bearing MCF-7 tumors. The 3H-SDG administration increased tumor tissue radioactivity to the level similar to that in brain, skin, spleen, kidney, uterus, and lungs. The tumor tissue radioactivity was up to 92% of that found in serum, with the highest concentrations found in small (< 0.5 g) tumors. Accessibility of lignans to tumor tissue suggests that part of the anticancer activity of lignans may be due to their direct local effects on the breast cancer tissues.