Legislation before state lawmakers in New York would significantly change medical malpractice law by allowing patients to sue years after an alleged misdiagnosis or mistreatment.

Patients currently must file lawsuits within 2½ years after the alleged malpractice.

The bill would amend the statute of limitations on such cases to start the clock when a patient first realizes they were possibly misdiagnosed or harmed by a medical professional — as long as the lawsuit is filed within 10 years of the original incident.

The Medical Society of the State of New York opposes the change, saying it would make medical malpractice insurance far more expensive and lead to “disastrous” increases in health care costs.

Supporters of the change say that when it comes to complex conditions such as cancer, it can take several years for a patient to realize they were misdiagnosed or otherwise mistreated by a physician or other medical professional.

Elissa McMahon was treated for what doctors told her were benign uterine fibroids in 2012 at a New York City hospital. In 2014, however, she learned she had advanced uterine cancer that already had spread to her liver and spine. She said her new doctors told her the disease should have been caught in 2012 — but since it had been almost three years it was too late to file a malpractice suit.

She’s now a leading supporter of the effort to pass the bill.

“The window was closed before I even knew,” said the 46-year-old single mother, who lives in the Boston suburbs. “I may not live to see this law passed, but if I don’t, and I helped pass it, then I’m glad I did it.”

Many states allow lawsuits for one to three years following the discovery of an alleged injury, though most require them to be filed within five years of the incident, regardless of when it was discovered. Supporters of the bill argue New York has one of the strictest windows in the nation, preventing many patients from having legal recourse.

The Medical Society, however, contends the New York bill would go too far by allowing date-of-discovery cases to be filed as long as 10 years — far longer than most other states. The state already has among the highest rates for medical malpractice insurance, said Elizabeth Dears, senior vice president and chief legislative counsel at the Society.

She said many states with more liberal statutes of limitations on malpractice claims also have caps on damages for pain and suffering — something New York does not have.

“Given that many hospitals and physicians all across New York State are barely able to keep their door open now … any increases of this nature would prompt a very serious access-to-care problem,” she wrote in the Society’s formal response to the bill.

The bill has broad support with the state Assembly’s Democratic majority and passed that chamber last year. But it faces obstacles in the Republican-led Senate. No vote is scheduled, but lawmakers intend to adjourn their session for the year later this month.

(AP)