An easier question would be what I haven't been worried about having. Lol, but anyway, here goes:
Brain tumor, ALS (repeatedly), Parkinson's, melanoma, diabetes, leukemia, colon cancer, ovarian cancer, esophageal cancer, breast cancer, oral cancer, COPD, lymphoma, cervical cancer. I am sure there are more that I cannot remember right now.
Now that I have kids I worry about their health too. It's exhausting!