Must every silver lining come with a drenching cloud? Medicine has made major advances in treating fearsome conditions like cancer, HIV-AIDS, congenital heart disorders, and infectious diseases. This progress has won deserved acclaim, edging some care givers to incautious use of a problematic four-letter word: cure.

Less known, however, are some later- and late-developing health challenges for patients once told they were free of what have been killer maladies. Some of the new and potentially big problems arise from the very lifesaving therapies that patients earlier received.

And while these unanticipated ills took time for patients and doctors to recognize and understand, they also offer an unpleasant reminder: Understatement and caution can be a best path for doctors, hospitals, and medical researchers. Patients also may wish to be wary of ways that Big Pharma and doctors talk about treatments and outcomes....