A very common question from so many patients. And very often it is difficult to give them a definitive answer. To make sense of this situation, it is natural to seek a reason for this cancer diagnosis, something they did or didn't do. But, for most patients, my answer is simple: We really don't know what caused your breast cancer. Now for about 10% of breast cancers, there can be an inherited genetic mutation on a specific gene that led to this cancer. But what about the other 90%? Unlike lung cancer, I can't blame this new diagnosis on a bad habit like smoking. Or melanoma from UV radiation from the sun. Certainly there are risk factors that contribute to an increased risk for breast cancer, such as age, hormone exposure, obesity, family history, etc. But a direct cause? No. I can't even blame hormones in every case, even though most patients ask about it. One thing that is very important for my patients to know is that they are not to blame for this cancer. Naturally, they want to find a reason for it, link it with something they did or didn't do. Lately my answer has been simple: Blame it on biology. We are learning more and more about how cancers form, from a molecular level, with various inflammatory mediators and molecular signals or receptors not working as they should to protect the body from cancer formation. This has led to development of therapies that specifically target these small changes, with the goal of minimizing the cancer potential at the molecular level. And even recently, scientists are looking at the beneficial effects of aspirin on decreasing breast cancer recurrence. How about bacteria? There is even evidence that certain bacteria might have the potential to slow cancer growth. More and more discoveries are forthcoming in the field of cancer and molecular biology. So even though I know it's not a great answer to their question, at least they can put less blame on themselves, and put more of it on biology.