Expert Shares Insight on Refinements in Breast Cancer Radiotherapy

Naamit K. Gerber, MD

There have been many advances in radiation oncology, but positioning techniques have shown the greatest impact on reducing the dose to the heart in patients with early-stage breast cancer, according to Naamit K. Gerber, MD.

The magnitude of benefit stems from relatively simple protocols like prone positioning or a deep inspiratory breath hold (DIBH), explained Gerber, an assistant professor in the Department of Radiation Oncology at NYU Langone’s Perlmutter Cancer Center.

“Unlike some of the other advances in radiation oncology that are technologically exciting, this is a pretty simple technique that has tremendous effects on our patients and the care we can give,” she said.

Beyond positioning, Gerber said that physicians are working to define the subset of patients who will derive the most benefit from regional nodal irradiation in the TAILOR RT trial (NCT03488693). The trial is currently accruing and is expected to complete in December 2027.

OncLive: What did your presentation focus on?

Can you elaborate on that protocol?

Is this technique used outside of NYU Langone's Perlmutter Cancer Center?

How have updates to the NCCN guidelines impacted the use of radiation in breast cancer?

In an interview during the 2018 OncLive^® State of the Science Summit™ on Breast Cancer, Gerber discussed recent advances in radiation therapy in the field of breast cancer.Gerber: I spoke about advances in radiation oncology. I started by talking about some of the advances in techniques that we've seen over the past few years. The advent of DIBH moves the heart away from the left breast or chest wall, which has been crucial in limiting the heart dose for patients who need radiation.We have patients take a really deep breath, which inflates the lungs and creates more distance between the heart and the left breast. It allows us to target the left breast and keep the cardiac dose extremely low. This technique is really useful both in patients with early-stage breast cancer who just need their breast treated, and also those with more advanced disease who need their lymph nodes treated.It's certainly not only [used] at NYU Langone's Perlmutter Cancer Center; it's becoming more frequent at more institutions. I was recently at a conference, and there was a presentation by a group in India that just implemented this. It's certainly becoming more widespread. Unlike some of the other advances in radiation oncology that are technologically exciting, this is a pretty simple technique that has tremendous effects on our patients and the care we can give. It's an important advance that should be further discussed.In the most recent version of the guidelines, there is a recognition that some women over the age of 70 with early-stage breast cancer don't need radiation after lumpectomy if they will receive endocrine therapy. Now, we have more accelerated radiation regimens, such as hypofractionated radiation, which takes place over 3 weeks or partial breast radiation that is given over 1 week at NYU Langone's Perlmutter Cancer Center.

Have treatment planning techniques like proton and intensity-modulated radiation therapy (IMRT) helped mitigate toxicity?

The risk-benefit ratio, in terms of deciding between doing some radiation and no radiation, is very different than when it was deciding between 5 weeks of radiation and no radiation. A lot of my patients, even if they're over the age of 70 and meet the criteria for omitting radiation, will choose to undergo partial breast radiation over the course of 1 week because there is a benefit to local control. Thankfully, the side effect profile is very minimal.In early-stage breast cancer, there has been no proven benefit of protons. There is an ongoing study looking at this in patients with slightly higher risk who need their internal mammary nodes treated. The jury is still out on whether the use of protons will become a useful modality in early-stage breast cancer. The techniques in positioning, such as prone positioning or DIBH, have shown the most benefit from a dose metric standpoint in terms of reducing the dose to the heart.

Is DIBH a cheaper alternative to IMRT?

Is DIBH becoming more common in practice?

In terms of IMRT, there have been many studies that compare IMRT with 3D. The multibeam IMRT studies show that you can sometimes achieve better target coverage, especially if you're trying to treat the internal mammary nodes. The tradeoff is that the low dose to the heart and the lungs goes up. With DIBH, we are often able to treat the nodes with 3D radiation with acceptable normal tissue toxicity without needing IMRT.The best thing we can do is position patients in the right position from the outset. I include holding the breath in the positioning. If you position patients prone or with a breath hold, you often don't need IMRT or other sophisticated technologies to achieve coverage and avoid the heart and the lungs, which are the most relevant at-risk organs. Unlike some other disease sites where IMRT and SBRT have improved outcomes, we've been able to use older techniques with newer positioning to achieve what we need to achieve.Thankfully, it is becoming more common. It is underappreciated by radiation oncologists. It’s an amazing innovation and it's not just for breast cancer. We use it in lymphoma cases where we're treating the mediastinum. It can be used in lung cancer cases as well, so it's not limited to breast cancer. There is not necessarily as much press about it because [it’s limited to the] doctors who use it. It's not as widely known among patients.

What is an area of research you would like to see addressed?

In recent years, prone breast radiation has become more widely known among patients and advocates. There was recently an editorial in the Red Journal by Bruce Haffty, MD, MS, who is one of the leaders of breast radiation oncology. [He wrote about how] so many of his patients think supine position [during radiation] is a terrible treatment because so many of his patients know about prone breast radiation. The word on prone radiation has gotten out, thankfully, but maybe too much, according to this editorial. DIBH isn't as well known among patients, but it should be.One of the studies that I presented in my talk that we're hoping to open up at NYU Langone's Perlmutter Cancer Center in the next month or two is the TAILOR RT trial. This trial will be using Oncotype DX to stratify patients and see whether they need regional nodal irradiation or no regional nodal irradiation. Patients who [had a lumpectomy] will get whole breast radiation versus whole breast plus regional nodal radiation. Patients who [had a mastectomy] will get no radiation versus chest wall plus nodal radiation.

We are trying to understand which subgroups will benefit most from regional nodal irradiation. We're using Oncotype DX as a surrogate to try to identify the patients with a worse biology. This is based on some data that show that Oncotype DX not only correlates with distant recurrence but also with local regional recurrence.

There is more of a push now to explore the use of hypofractionated radiation in patients who have had a mastectomy. That's something that is on the horizon. It has become much more widely adopted in patients with early-stage breast cancer with intact breast.

What would you like community oncologists to apply to practice?

Partial breast radiation is something we do a lot of at NYU Langone's Perlmutter Cancer Center, but it is not as widespread as you might expect it. In August 2017, Lancet Oncology published a very large study from the United Kingdom comparing partial breast radiation with whole breast radiation in almost 2000 patients showing equivalent outcomes. I hope that partial breast radiation becomes more common as the data accumulate.One thing that I didn't talk about but is very important is the expansion of the ASTRO whole breast hypofractionated guidelines. They were published in the past few months. Unlike the prior version of the 2011 guidelines, which only recommended hypofractionated radiation in women over 50, women who would not receive chemotherapy, or those with invasive disease, the new guidelines have expanded the indications to include women of any age, women who have received chemotherapy, and those with ductal carcinoma in situ. This is really wonderful for our patients for whom the shorter course of radiation is much more convenient. Following these ASTRO guidelines is imperative.

[We also have to] encourage the use of prone breast radiation and DIBH because it really has tremendous benefit for our patients.