The reason tomatoes aren't accepted in a macrobiotic diet is because they're a nightshade and cause the blood to become too acidic. Acidic blood leads to poor health. Healthy blood is slightly alkiline.
I believe Macrobiotics is the best solution for cancer. A friend of my father's cured his cancer with it. Don't shun it just because it uses Japanese ingredients. The 60% grains and 30% vegetables should both be locally grown and organic. The Japanese things are only a small portion of the diet. You don't import all your food from Japan or something crazy like that.