Sure, you may have smoked, and while that may likely have contributed to your disease, the operative word is "may." "Sometimes the factors that cause our illnesses are related to things that we can't help at all—environmental exposures, congenital problems, familial issues, and even bad luck," says Dr. Antonoff. "Lung cancer is multifactorial, and we don't know for any one individual exactly what caused their tumor cells to grow."
So your particular lung cancer might have more to do with the chemicals you've been exposed to at work, for instance. And since you don't know for sure and neither does your oncologist, stop beating yourself up—and move on to the next item on this list.