Radiation Therapy Updates for Breast Cancer in the NCCN Guidelines

Surabhi Dangi-Garimella, PhD

On the second day of the 22nd Annual Conference of the National Comprehensive Cancer Network (NCCN), in Orlando, Florida, Kilian E. Salerno, MD, of the Roswell Park Cancer Institute, walked the audience through updates to the NCCN Guidelines, explaining clinical situations in which radiation is indicated, appropriate targets of radiation treatment, and optimal approaches for minimizing toxicity.

Understanding the target area is important, Salerno said, because the treatment options and the treatment plan and delivery need to be optimized per the patient’s needs. “The target region to receive the radiation dose can vary. It might be the whole breast; partial breast, where we may target the lumpectomy cavity; the chest wall; or just regional nodes.”

The dose varies according to the target region:

1. Conventional fractionation is a dose of 1.8 to 2 Gy per fraction, for a total dose of 45 to 50.4 Gy.

2. Hypofractionation is typically a shorter course that uses larger doses per fraction. More than 2 Gy may be used per fraction to lower the total dose, which can be:

3. The accelerated course is usually treatment over a shorter time course. Clinics have several options for the source of radiation to choose from, Salerno said. The sources of radiation include:

The NCCN Guidelines for breast cancer, updated in March 2017, provide the guidance on target definition and optimizing therapy for an individual patient as needed. “Greater target dose homogeneity and sparing of normal tissues can be accomplished using compensators such as wedges, forward planning using segments, and intensity-modulated radiation therapy,” the guidelines stated.

The most commonly used techniques include:
The updated guidelines also provide information on patients who have undergone breast conservation but in whom radiation therapy is contraindicated.

An absolute “No” includes:
Relative contraindication in case of:
“Identifying an appropriate margin has been a topic of debate and the new Guideline provides direction,” said Salerno. “We must remember, though, that context matters.” The following 2 recommendations have been added to the Guideline:
Salerno then spoke about locoregional treatment of clinical stage I, IIA, or IIIB disease or node-positive disease. For negative axillary nodes the following treatment options have been recommended:

She then provided insight on post mastectomy radiation (PMRT), classic indications for which include 4 or more positive axillary lymph nodes, positive margins, and tumor size over 5 cm. However, patients with 1 to 3 lymph nodes, close margins and some high-risk features, such as age, extracapsular extension, and certain intrinsic subtypes, could also be considered for PMRT.

Regional node irradiation or RNI is recommended for those with 4 or more positive nodes, strongly considered for 1 to 3 positive nodes, and may be considered for some high-risk node negative patients.
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