Other doctors agree that the risks for the additional radiation are minimal. "This extra dose is not a high dose. So the extra side effects are marginal," says Weiss. She adds that patients can expect "just a little more transient swelling, tenderness and redness."
The researchers are looking to the future, for more ways to improve radiation therapy for women with breast cancer.
"We have just started another trial, with 1,800 women," says Bartelink. "Using tumor material we take from biopsies, we can predict which patients will need radiation, and how much they will need."
This type of personalized treatment for breast cancer may reduce the risk of breast cancer recurrence as well as reduce the need for mastectomies, according to Bartelink.
"Boosts do decrease the recurrences at the tumor bed," says Dr. Anne Rosenberg, a breast surgeon at Jefferson Medical College in Philadelphia. "This is especially important in young women, where their life expectancy is greater, and so the risk of recurrence in the future is greater."
Study author Bartelink is optimistic about future advances in radiation therapy.
"This is a major step forward, especially for the younger women," he says. "We are continuing to learn more."