False. False-positive results, which suggest cancer where there really isn’t any, are common. It’s estimated that over the span of a decade the results of 50 to 61 percent of mammograms, 10 to 12 percent of PSA tests, and about 23 percent of regular fecal occult blood tests (a stool test) will be false-positive. False-positives may be caused by another disease or no disease at all.
True. Screening tests themselves carry risk. They may cause complications or side effects, or false-positive result that lead to unnecessary treatment. That's why doctors and scientists study whether the benefits of a screening test outweigh its risks before it’s recommended for widespread use. Sometimes screening makes sense for people only at high risk because of their age, health, or family history.