Partial-breast Radiation OK for More People in New ASTRO Guidelines

The American Society for Radiation Oncology (ASTRO) released new guidelines for the use of accelerated partial-breast radiation to treat early-stage breast cancer that opens the door for more people to get this treatment.

Background and Goals

ASTRO is a national organization of 10,000 health care professionals who specialize in radiation therapies. It works to make care for people with cancer better through education, advocacy and better health policies. The September 2016 release was an update to ASTRO’s guidelines on accelerated partial breast radiation first released in 2009.

Most people who get radiation therapy to treat breast cancer get whole-breast radiation, in which a radiation oncologist uses a machine to direct beams of radiation at the affected breast. Accelerated partial-breast radiation started being offered in the 1990s. It uses methods that allow larger doses of radiation to be directed to a smaller part of the breast that is most likely to be affected by the cancer. One benefit is that accelerated partial-breast radiation is given over fewer treatment days.

While many people can be treated with partial breast radiation, it may raise the risk of recurrence for some people with breast cancer. The ASTRO guidelines are meant to help doctors identify when partial-breast radiation can work as well as whole-breast radiation, using features like tumor stage, margins and age.

There are a few different types of partial-breast radiation, including:

• brachytherapy, in which catheters holding a radioactive seed or seeds are placed in the part of the breast where the tumor was removed in a lumpectomy
• external beam radiation, which is the same as the method used for whole-breast radiation, but is planned to focus on a smaller area around the tumor
• intraoperative radiation therapy, also called IORT, which is a high dose of radiation given once during breast surgery to the area around where the tumor was removed

Design

Recent clinical trials have provided more information on the uses of partial-breast radiation since ASTRO’s first guidelines in 2009. Researchers selected 44 studies, found with the same search terms used for the first guidelines, to look at new data on using partial-breast radiation. Their focus was the key question from the previous guidelines: “Which patients may be considered for [advanced partial-breast radiation] outside of a clinical trial?”

ASTRO also considered a new question for the update: Who should be considered for IORT?

Results

Age

The new guidelines lowered the age limits for whom ASTRO considers OK to be treated with partial-breast radiation by 10 years. According to the new guidelines, people who are 50 years or older are “suitable” to get partial-breast radiation if they don’t have certain conditions, like close surgical margins or a diagnosis of ductal carcinoma in situ with a tumor greater than 3 centimeters in size. This is down from ages 60 and older in the original 2009 guidelines. ASTRO looked at three studies specifically that included women as young as age 40 and did not find a significantly higher risk of recurrence.

ASTRO also brought the age for their “cautionary” group down by the same time span, from ages 50 to 59 in the 2009 guidelines to ages 40 to 49 in the new guidelines. Researchers don’t have enough data to say whether or not most people in this group are suitable for partial-breast radiation, so they recommend being careful in deciding to use it outside of clinical trials. In this case, the studies included women ages 40 to 50 and found no higher risk of recurrence with partial-breast radiation, but the sample sizes were too small for ASTRO to make a recommendation from those results.

DCIS

Some people with DCIS are also able to get partial-breast radiation now, where the previous guideline recommended it only for invasive breast cancers. DCIS cases ASTRO considered suitable are:

• found in a regular screening, not from symptoms
• it is smaller than 2.5 centimeters
• the margins have no cancer within 3 millimeters of the edge
• low or medium nuclear grade

IORT

ASTRO also announced its first guidelines for the use of IORT in people with breast cancer. Two types of IORT are addressed. The guidelines said electron beam IORT, which applies radiation to the area where the tumor was removed using electron beams, can be considered for women who meet the age and other requirements they set for partial-breast radiation. They said low-energy x-ray IORT, which uses x-rays to apply radiation, should be limited to clinical trials for now and also only for women who meet the other requirements.

ASTRO recommends telling anyone who is given the option to have IORT that the risk of recurrence was found to be higher in people who got IORT instead of whole-breast irradiation in the two studies that have looked into it.

What This Means for You

Whole-breast radiation is the standard radiation therapy to treat many early-stage breast cancers, especially after a lumpectomy, but you may have to go to your treatment center 5 days a week for 3 to 7 weeks. You may like the idea of fewer weeks in treatment with partial-breast radiation, but there are also risks to consider.

Some studies have found breast cancer was more likely to return after treatment with partial-breast radiation treatments compared with whole-breast radiation. Partial-breast radiation is still relatively new and as more information is released researchers are finding groups where there is no or little difference in how well the methods treat the disease and offer those people the option that causes less discomfort.

ASTRO’s new guidelines may allow more people to get partial-breast radiation. Speak with your doctor if you think these new guidelines make you eligible for partial-breast radiation. Your doctor can explain some of the risks and questions that remain about partial-breast radiation.

Correa, C; Harris, E; Leonardi, M.; et al. Accelerated Partial Breast Irradiation: Executive summary for the update of an ASTRO Evidence-Based Consensus Statement. Practical Radiation Oncology.

September 17, 2016.