This randomized phase III study, which involved researchers at the OSUCCC – James, compared whole breast irradiation with partial breast irradiation in a large group of women with stage 0, 1 or 2 breast cancer. More than 4,200 patients were enrolled in the study as part of an NRG Oncology cooperative group clinical trial.
Study results showed that, while partial breast irradiation does not produce equivalent cancer control for all breast cancer patients with stage 0, 1 and 2 disease, it should still be considered as an alternative for women with DCIS (ductal carcinoma in situ) and early-stage breast cancers deemed “low risk” based on other tumor characteristics.
Among the entire study population, women who received partial breast irradiation experienced a 4.6% recurrence rate. Those who underwent whole breast irradiation experienced a 3.9% rate of recurrence. Toxicity from treatment was similar, as well as the risk for secondary cancers.
However, researchers also looked at how this played out in sub-segments of the population and found that rates of recurrence were nearly identical for women with DCIS, regardless of whether they received whole or partial breast irradiation. This was also true for women with breast cancer classified as low risk based on American Society for Radiation Oncology (ASTRO) clinical guidelines.
Researchers showed that, in this sub-segment of breast cancer patients, the likelihood of recurrence 10 years post-treatment was very low overall and almost identical between women who received whole breast irradiation (2.3%) and partial breast irradiation (2.7%).
Julia White, MD, co-principal investigator of the national trial and head of breast radiation oncology at the OSUCCC – James, says this is very important because it reduces the burden of care for women who can still achieve cancer control with fewer treatments over a shorter period.
“A significant portion of the breast cancer patient population nationally — about 25,000 to 30,000 women — would qualify for partial breast irradiation. This is tremendously important because it allows us to give women the right amount of treatment for their disease and potentially allows better access to effective breast conservation for those who live far from a radiation facility,” says White, who also is a professor in the Department of Radiation Oncology at Ohio State and a member of the Translational Therapeutics Program at the OSUCCC – James.
“Partial breast irradiation can also be delivered in five consecutive days versus whole breast, which can involve four to six consecutive weeks of multi-day treatment,” White adds. “There is no denying that the five-day treatment is less costly and less disruptive to life.”
At the OSUCCC – James, breast radiation is also delivered in the face-down (prone) position to reduce radiation exposure in the chest wall, which has been linked to increased risk of heart and lung disease post-cancer treatment.
Data from this NRG Oncology study was presented at the 2019 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago.