Like "Should have mentioned below that cancer cells have a harder time multiplying if your Vitamin D levels are normal. Easy blood test to include. My doc tells me that most people's are below normal. I take this little rubber pill every morning as a supplement, and yes my last blood test showed a level of 60 (mid-range). Doc was surprised. Check it out. Obviously if you can't quit smoking, you might as well, at least, inhibit their growth. "