The bowel cancer screening age will be lowered to 56 years old, Government says, allowing tens of thousands more people to get checked.

The screening age will change from 58 to 56 years old in September, Health Minister Simeon Brown said on Thursday.

The rollout is expected to take two years. By September 2028, another 200,000 New Zealanders will have become eligible for screening.

It was estimated that over the next 25 years, the expansion of the scheme would prevent 638 bowel cancers and save 522 lives.

"Earlier diagnosis means faster treatment, better outcomes and ultimately more lives saved," Brown said.