Fat stands as a biggest factor causing breast cancer, and avoiding it ensures less chances of breast cancer. How does fat cause breast cancer has already been discussed here. Including vegetables in your diet can work best to reduce the amount of fats intake.

Cruciferous vegetables like, broccoli, brussel sprouts, cabbage, turnips and cauliflower and some others can make a good variety in your diet. Vegetables are, however, effective only if they’re cooked I a way that their nutrients are not wasted. So, the best way is to steam them or eat them raw. Vegetables actually contain a good number of nutrients that help fighting cancer, so eating them in a state that they have maximum nutrients will work best.
The vegetables mentioned above contain sulfurous compounds called indoles that help eliminating estrogen from the body, and so they help preventing the body from accelerated growth of breast cancer.