A bill that would require large group insurers to cover mammograms for women between the ages of 35 and 39 was signed into law Friday by Gov. Andrew Cuomo.

The measure is known as “Shannon’s Law” — named in honor of a Long Island woman who was diagnosed with breast cancer at 28 and died at 31.

“We know that with cancer diagnoses, early detection is the best possible treatment. This administration has taken and will continue to take aggressive action to break down any barriers to breast cancer screenings for women across the state,” Cuomo siad.

“By signing this legislation, we are taking another step to break down barriers to breast cancer screening and improve access to health care for all women in New York.”

Many large insurance companies are required to cover mammogram screenings for women over 40. But there are also 12,000 cases of breast cancer diagnosed each year among women under age 40.

The new law requires large insurance companies to cover the mammograms when medically necessary.

“I strongly believe in the importance of early detection, and it is imperative that individuals under 40 have access to annual mammograms when deemed medically necessary,” said Sen. Monica Martinez. “With 1 in 8 women developing breast cancer in their lifetime, the enactment of this bill is critical to enabling early detection and saving lives.”