Did the effect of the dietary intervention on risk of breast cancer differ by tumor type, such as estrogen receptor status or progesterone receptor status?
Yes, women in intervention group experienced a significantly greater reduction in the risk of progesterone receptor negative breast tumors than in the risk of progesterone receptor positive tumors. It appeared that the low fat dietary pattern may have had the most benefit in preventing tumors that were both estrogen receptor positive and progesterone receptor negative. These findings support the argument of some effect of the intervention on breast cancer risk, and reinforce the view that breast cancer is a heterogeneous diagnosis with several major subtypes.
