Research from the US says unnecessary medical testing can do more harm than good for patients.

New York's Memorial Sloan Kettering Cancer Centre says a wide-net testing approach can do physical, mental and social harm.

Dr Deborah Korenstein says individual tests can be invasive, and any false positive or negative can burden someone psychologically.

She told Tim Dower it calls into doubt the "more is better" medical approach.

"So if you're doing things that aren't necessary you're subjecting them to the harms without any potential benefit."

LISTEN ABOVE AS DEBORAH KORENSTEIN SPEAKS WITH TIM DOWER