DETROIT – For the past 17 years, Anna Dorosh of Dearborn, Mich., has battled non-life-threatening forms of skin cancer and kidney cancer. But new research indicates there is little chance her son Ronald, 54, who has Down syndrome, will develop cancer.

Ronald Dorosh and others with the condition caused by three copies of chromosome 21 have a very low risk of getting tumors, and new research from Children’s Hospital in Boston sheds light on a possible reason why.

The extra chromosomes carried by those with Down syndrome create a third helping of a tumor blocker that keeps blood away from budding cancers.

The finding could lead to new treatments for anyone with cancer, said lead researcher Sandra Ryeom of the Children’s Hospital Vascular Biology Program.

“It’s an amazing clue from a very unique population,” she said.

By examining cells from people with Down syndrome, and reproducing cancer conditions in mice, Ryeom and colleagues showed a specific gene – in three copies – makes more of the tumor blocker than people and mice with only two copies of the gene. The excess tumor blocker, Dscr1, stops blood vessels from forming – and without nutrients and oxygen from blood, tumors can’t grow.

“We want to make cancer manageable,” Ryeom said. The next step, she said, is to see how the extra amount of Dscr1 works in people without Down syndrome who have cancer.

Anna Dorosh, 88, said she finds comfort in knowing that cancer is much less of a worry for her son.

“Whatever my children don’t have to experience, I’m happy about it,” she said. “I think that every mother just wants to see their children happy.”