The American Society for Radiation Oncology (ASTRO) has released evidence-based guidelines supporting the use of hypofractionated (HF) whole breast irradiation (WBI) for certain patients with early-stage breast cancer, based on the findings of a study published in the August edition of the International Journal of Radiation, Oncology, Biology and Physics.
The ASTRO Health Services Research Committee organized a task force, led by Benjamin D. Smith, MD, radiation oncologist at the University of Texas MD Anderson Cancer Center in Houston. Smith and colleagues compared the difference in local control and survival outcomes between patients with early-stage breast cancer treated with breast-conserving surgery, who were then treated with conventionally fractionated (CF)-WBI or HF-WBI, in order to develop guidelines to direct clinical practice.
Specifically, ASTRO charged the task force with answering the following questions:
1. Which patients obtain equivalent results from HF-WBI and CF-WBI?
2. What is the role of a tumor-bed radiation boost in patients treated with HF-WBI?
3. What are appropriate regiments for HF-WBI and tumor-bed boost?
4. What are the characteristics of an acceptable radiotherapy plan for patients treated with HF-WBI?
5. What insights relevant to the radiobiology of breast cancer can be gained from recently published clinical trials comparing CF-WBI with HF-WBI?
The researchers systematically reviewed literature of patients (ages 50 and older) in randomized trials who had disease Stage pT1-2 pN0, did not receive chemotherapy and were treated with a radiation dose homogeneity within 7 percent in the central axis plane.
Smith and colleagues determined that the aforementioned patients experienced equivalent outcomes with either HF-WBI or CF-WBI. For patients not receiving a radiation boost, the task force favored a dose schedule of 42.5 Gy in 16 fractions when HF-WBI is planned. For patients who do not meet these criteria, the authors wrote that there was not enough evidence to reach a consensus for or against the use of HF-WBI.
However, the authors stressed that the guideline "should not be interpreted to prohibit or oppose the use of HF-WBI for patients not meeting all the criteria."
The researchers further recommended that the heart should be excluded from the primary treatment when HF-WBI is used, as uncertainty remains regarding late effects of HF-WBI on cardiac function. In addition, the appropriateness of a tumor-bed boost in patients treated with HF-WBI could not be determined by the task force.
“Widespread adoption of HF-WBI for appropriately selected patients has the potential to enhance the convenience of treatment and lower the costs of WBI," said Smith, "For patients where the data to support HF-WBI are not as strong, HF-WBI can still be considered an option but further research is needed."