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Intense, Short-Term Radiation Therapy Safely and Effectively Treats Breast Cancer

October 20, 2015

PHILADELPHIA (October 20, 2015) – Treatment of early-stage breast cancer with fewer, larger doses of radiation results in equivalent clinical outcomes as conventional radiation therapy, according to new research by Fox Chase Cancer Center – Temple Health investigators. The study revealed no significant difference in survival rates or long-term side effects in patients who received either intense (hypofractionated) radiation therapy over a four-week period or standard radiation therapy over a six- to seven-week period. The eight-year results of the prospective Phase II study were presented October 20 at the 57th Annual Meeting of the American Society for Radiation Oncology (ASTRO) in San Antonio, Texas.

Breast cancer is the most common cancer among women in the United States, affecting one in eight women during their lives and killing more women than any cancer except lung cancer. Standard radiation therapy, which is given after surgical removal of the tumor, requires daily treatment for about five weeks. Typically, whole-breast irradiation is followed by one to two weeks of radiation boost treatment targeting the tumor bed—the recurrence-prone tissue surrounding the cancerous tumor.

Even though radiation therapy significantly reduces the risk of local recurrence and increases patient survival, many women do not undergo this standard procedure because of the inconveniently long treatment duration and the associated high health care costs. Hypofractionated radiation therapy is an attractive alternative because it shortens the treatment duration by weeks and costs patients substantially less money. Prospective clinical trials have shown promising results for hypofractionation in breast cancer patients, but none of them incorporated a simultaneous tumor bed boost, which significantly reduces the risk of local recurrence.

Fox Chase investigators initiated a clinical study in 2003 to address this limitation. Seventy-five patients were treated with hypofractionated whole-breast intensity modulated radiation therapy (IMRT) with an incorporated tumor bed boost, while an additional 172 patients were treated off trial in a similar manner. These patients were treated with a total of 56 Gray delivered in 20 fractions over a four-week period, with the whole breast receiving 2.25 Gray per fraction and the tumor bed receiving an additional 0.55 Gray per fraction concurrently. Meanwhile, another set of 460 patients with early-stage breast cancer were treated with 50 Gray of conventional IMRT delivered to the whole breast in 25 fractions over five weeks, followed by a sequential 10- to 16 Gray boost.

In 96 percent of patients who received either hypofractionated or standard IMRT, there was no evidence of cancer growth at the site of origin eight years later. There was also no significant difference between the two groups in overall survival rates, risk of death related to breast cancer, risk of distant metastases, cosmetic appearance, or long-term side effects. However, 46 percent of patients treated with conventional IMRT experienced short-term, moderate to severe complications that primarily affected the skin, in contrast to 20 percentof patients treated with hypofractionated radiation.

“The findings demonstrate that the four-week course of hypofractionated whole-breast radiation with an incorporated boost is associated with comparable long-term outcomes, and fewer acute side effects, compared with conventional fractionation with a sequential boost,” said lead study investigator Lora Wang, MD, a resident in the department of radiation oncology at Fox Chase. “This study, along with the long-term results of previous prospective randomized trials from Canada and the UK, shows that hypofractionated radiation therapy for the whole breast is well tolerated and can be used safely and effectively as an alternative to conventionally fractionated whole-breast radiation, with a shorter overall treatment time.”

       

Fox Chase Cancer Center, part of the Temple University Health System, is one of the leading cancer research and treatment centers in the United States. Founded in 1904 in Philadelphia as one of the nation’s first cancer hospitals, Fox Chase was also among the first institutions to be designated a National Cancer Institute Comprehensive Cancer Center in 1974. Fox Chase researchers have won the highest awards in their fields, including two Nobel Prizes. Fox Chase physicians are also routinely recognized in national rankings, and the Center’s nursing program has received the Magnet recognition for excellence four consecutive times. Today, Fox Chase conducts a broad array of nationally competitive basic, translational, and clinical research, with special programs in cancer prevention, detection, survivorship, and community outreach.  For more information, call 1-888-FOX CHASE or (1-888-369-2427).