Initial results of these trials “supported the safety and effectiveness of HF-WBI” and were then used to form ASTRO’s 2011 guideline on dose fractionation for WBI. With longer term data from these trials now available, it was time to review the evidence again. A systematic literature review was thus conducted to identify all relevant studies published during 2009-2016, and 100 articles met the task force criteria and were used to create the updated guideline.
Aside from the delivery and dosing of WBI, other key recommendations look at the use of a radiation boost to the tumor bed, and preferred techniques for treatment planning.
With regards to a radiation boost, this needs to be considered on an individual basis but can be independent of any previous WBI. A radiation boost is recommended if patients have any grade invasive cancer and are aged 50 years or younger, have a high-grade tumor and are aged 51-70 years, or if there is a positive margin following surgery. A radiation boost also is recommended in women with ductal carcinoma in situ if they are aged 50 years or younger, have a high-grade tumor, and positive or close postsurgical margins.
As for treatment planning, 3-dimensional conformal treatment planning with a “field-in-field” technique is recommended as the initial approach. This is to minimize the volume of breast tissue that receives more than 105% of the radiation dose. The guideline also covers optimal patient positioning and how to avoid nearby tissues and organs, such as the heart, lungs and contralateral breast.