Does constant worry and fear when younger increase chances of developing cancer when older?

No: Actually, it is a biologically interesting and complex question which could only be answered in detail with very large population studies (very, very expensive). However, child abuse - as a paradigm example - is certainly associated with later stress disorders but not with cancer. (Remember, finding an example or two doesn't prove cause-and-effect. Otherwise, breathing would cause cancer.)

Not really: There is no correlation between anxiety and cancer, that we know yet. Although many behaviors and habits could be dangerous in persons with anxiety, like smoking cigarettes and drinking alcohol in excess. Anxiety is treatable by psychotherapy and medications, very successfully and safely.

No: Anxiety is not known to be a risk factor for cancer.