Personalizing Locoregional Treatment for Breast Cancer

ASCO Daily News

Dr. Dionisia Quiroga discusses emerging approaches to personalizing locoregional treatment for breast cancer with Drs. Walter Paul Weber and Charlote Coles, who share insights on tailoring axillary surgery, escalating lymphatic surgery, and implementing hypofractionated radiotherapy.

TRANSCRIPT

Dr. Dionisia Quiroga: Hello, I'm Dr. Dionisia Quiroga, your guest host of the ASCO Daily News Podcast today. I'm a breast medical oncologist and assistant professor in the Division of Medical Oncology at the Ohio State University Comprehensive Cancer Center. On today's episode, we'll be discussing emerging approaches to personalize locoregional treatment for patients with breast cancer, including many of the latest updates on axillary surgical staging, lymphatic surgery, and evidence-based radiotherapy in the treatment of breast cancer.

We're very fortunate to have joining me today for this discussion Dr. Walter Paul Weber, a professor and head at the Division of Breast Surgery at the University Hospital Basel in Switzerland, and Dr. Charlotte Coles, a professor of cancer clinical oncology and the deputy head of the Department of Oncology at the University of Cambridge in the United Kingdom.

Our full disclosures are available in the transcript of this episode. Dr. Weber and Dr. Coles, it's very wonderful to have you on the podcast and thank you so much for being here.

Dr. Walter Paul Weber: Thank you very much for having us.

Dr. Charlotte Coles: Thank you.

Dr. Dionisia Quiroga: Now, for many decades prior, axillary lymph node dissection has very much been our standard of care. But recently, axillary surgeries have been able to be gradually deescalated to spare some of our patients from relative and relevant long-term morbidity. There are still some indications in which axillary lymph node dissection still remain. And therefore, we still see breast cancer-related lymphedema, a well-known sequela of the axillary surgery to continue to be prevalent. And I think it's important also to acknowledge that today there's about an estimated 1.5 million cancer survivors who deal with breast cancer-related lymphedema. Now, Dr. Weber, at the recent ASCO Annual Meeting, you and your co-presenters discussed tailoring axillary surgery, escalating lymphatic surgery and implementing evidence-based hypofractionated radiotherapy to really personalize locoregional treatment for people who've been diagnosed with breast cancer. And in addition to that, you and Dr. Coles have also published this work in the 2024 ASCO Educational Book. Can you tell us about some of the recent advances in axillary surgery and what are really the current indications for axillary dissection?

Dr. Walter Paul Weber: Yes, I'm happy to do so. So as you've said, we've known for a while that we can omit axillary dissection in patients with clinically known negative breast cancer and negative sentinel nodes. We've known for about 10-15 years that we can omit axillary dissection in patients with one or two positive sentinel nodes in many patients. But what we've learned recently is that we can omit axillary dissection also in patients with one or two positive sentinel nodes who have larger primary tumors who undergo mastectomy or who have extranodal extension. This is a landmark trial that was published just a few months ago, the SENOMAC trial that established this. The remaining indications for axillary dissection are situations where you expect a heavy tumor load in the axilla. For example, when you have more than two positive sentinel nodes or you have a patient with clinically node-positive breast cancer who undergoes upfront surgery and has palpable disease or significant disease on imaging. Patients with locally advanced breast cancer, who are considered by some to be not eligible for nodal downstaging, such as patients with CN2, CN3 disease or CT4 breast cancer. And then the big group of patients who have residual disease after neoadjuvant chemotherapy in the nodes, standard of care is still axillary dissection.

But we now have some real-world evidence that it's safe for selected patients with low volume nodal disease left in the nodes, mostly isolated tumor cells, to not undergo axillary dissection. So these are the remaining indications today.

Dr. Dionisia Quiroga: Can you speak to situations where maybe even sentinel lymph node biopsies might be omitted? I know you spoke a little bit about the use of imaging in your work.

Dr. Walter Paul Weber: Yes, this is correct. So, we started about maybe 7 or 8 years ago to omit sentinel lymph node biopsy in older patients above 70 years of age who have luminal disease, according to recommendations from the Choosing Wisely initiative. And now indeed there are several ongoing randomized trials that investigate if axillary imaging can replace surgical staging of the axilla.

And the first of these trials was published recently, the SOUND trial with almost 1,500 patients, who underwent breast conserving surgery and had small tumors and all had a negative ultrasound of the axilla. And then they were randomized into a sentinel lymph node biopsy versus no axillary surgery. And that trial showed non-inferiority of the omission of sentinel lymph node biopsy in these patients.

Now, it's a bit early to roll out the Choosing Wisely recommendation to all patients who have a negative ultrasound. The SOUND trial showed that about 14% had a false-negative ultrasound. So, in the control arm, they actually did have a positive sentinel node. And in patients where that one missed sentinel node makes a big difference in terms of systemic therapy, most experts would still recommend sentinel biopsy, and these are patients mainly with HER2-positive or triple-negative breast cancer or premenopausal patients or those who have G3 biology.

Dr. Dionisia Quiroga: I think you bring up a very important point. Coming from the side of a breast medical oncologist, we're also very interested to see what these studies show because many of our practices are based on what we find out from our lymph node biopsies. So, I think a lot of interesting prospective studies to look at in the future.

Dr. Walter Paul Weber: Absolutely.

Dr. Dionisia Quiroga: One other topic we wanted to discuss was local regional management of stage four disease and particularly oligometastatic disease. And this is not a new topic of interest. We've been speaking about this for a long time in breast cancer management, but can you address some of the axillary management strategies that you currently use for stage 4 disease?

Dr. Walter Paul Weber: Yes, it depends on your intention. If your intention is to cure the patient, then you would apply all the locoregional standards that apply in the curative setting, which means lymph node biopsy with or without axillary dissection. Now in a palliative situation, it's individualized. Very often you don't touch the axilla and sometimes you open it and just remove palpable disease, trying to minimize morbidity. The question of which intent you should follow is controversial; three out of the four randomized trials did not show a benefit for locoregional surgery in patients with de novo stage 4 disease. However, experts seem to disagree. The last St. Gallen consensus recommendation was in favor of the curative intent in such a patient with oligometastatic disease; 85% favored the curative intent. So there's a bit of discrepancy there, but everybody would agree, and this is what has been done in all of these trials, that if you try to cure the patient, then you should apply the curative standards of sentinel and axillary dissection that you use also in early-stage breast cancer.

Dr. Dionisia Quiroga: Thank you. Now, moving on from surgical axillary management and more into lymphedema prevention and treatment. Can you speak to some of the promising advances that have happened in this field?

Dr. Walter Paul Weber: Yes, so the best way to prevent lymphedema still is not to perform axillary dissection, which is the number 1 risk factor, which is all the axillary surgery de-escalation research that we've just discussed is all about. Prevention of lymphedema is one major aim of this. Now, once you indicate axillary dissection and you expect the patient to be at high risk – for example, if there are other risk factors such as obesity or neoadjuvant chemotherapy or extended regional nodal radiotherapy, then indeed there are emerging techniques that really seem to work. There is some evidence supporting it, which is categorizable as immediate lymphatic repair basically or bypass. And that is usually in a patient who undergoes axillary dissection, and also undergoes axillary reverse mapping. That allows the identification of the lymph nodes that are probably most relevant to the drainage of the lymphatic fluid from the arm. And then you can try to spare these. But if you decide, and this is effective, there is a consistent body of evidence, not phase 3 trials, but pretty consistent evidence that axillary reverse mapping works just by sparing the identified nodes.

But if you decide that you have to remove these nodes as part of the radical concept of axillary dissection, then immediate lymphatic repair is also increasingly being done and is also supported by consistent evidence, even some single center randomized trials, low volume, but all consistently showing quite a striking benefit of this immediate lymphatic repair technique.

There are different ways you can do it. You can either use it the microscope, and it's being done by the plastic surgeons, but it's also a simplified technique described that can be used by specialized general and breast surgeons. Both techniques seem to really work based on what we know from the studies, but also based on our common sense.

Dr. Dionisia Quiroga: You talked about the procedures that can be offered to patients at time of breast surgery. And unfortunately, many of our patients maybe did not have the availability of those techniques when they undergo their initial breast cancer treatment. Once lymphedema is developed in a limb following breast cancer diagnosis, can you speak to other interventions that can be done to potentially help mitigate lymphedema?

Dr. Walter Paul Weber: Right, so for patients who no longer benefit from or wish to further undergo conservative treatment of lymphedema, there are emerging procedures that are now out of my personal comfort zone because they're being performed by plastic surgeons; they use the microscope. There are two groups, the lymphovenous anastomosis and then the real vascular lymph node transfer as a free flap. And both of these procedures (there are no randomized trials yet published), but some really good ones are on the way and currently recruiting based on the evidence we have, which is over 20 observational studies all consistently again showing a benefit in terms of what you can measure in terms of centimeters or with a bioimpedance spectroscopy, or also when you ask the patients, you see quite some dramatic improvements by both of these techniques. And it's increasingly being done. Personally, I strongly believe that it works based on everything we know and understand from lymphedema development, but also prevention and treatment. So I am quite sure that in 5-10 years, we will see much more surgical treatment of patients with lymphedema by highly specialized plastic surgeons.

Dr. Dionisia Quiroga: That's my hope as well. Now, another important component of local regional treatment we know is of course radiotherapy. And there have been many incredible advances in breast radiotherapy over the past decades, which has really improved cancer control and decreased side effects in our patients. Dr. Coles, you've led practice changing radiotherapy trials in the past and your research has really influenced international hypofractionation policy.

Can you expand upon the emergence of hypofractionated radiation for breast cancer and the effects that it can have on our patient care?

Dr. Charlotte Coles: Yes, so thank you very much, Dr. Quiroga. So I think the first thing to say is that radiotherapy hypofractionation isn't a new concept. And in fact, the breast radiotherapy hypofractionation trial started around three decades ago. And the rationale for this was the hypothesis that breast cancer is as sensitive to fraction, which is the treatments that we give, we split it into fractions, is sensitive as late responding tissue. So what does this mean? It means that the small traditional 2 Gy fraction spare tumor and normal tissues equally, so there's no advantage. So therefore, fewer fractions with a larger dose per fraction are worth testing.

The problem is there's a concern that hypofractionation might increase the risk of side effects, and that includes the really important one we've been talking about, lymphedema. But we can reduce this risk by reducing the total radiotherapy dose over the whole course. But the question was by how much. So that's why randomized trials were needed. And there's been really high-quality trials with robust radiotherapy quality assurance, and they've been designed in partnership with patients. So just a very quick run through: A landmark trial was the UK START B trial. And this was a pragmatic design that compared 50 Gy in 25 fractions, which was commonly used in the south of the country with 40 Gy in 15 fractions, which was used at that time in the north [of the UK]. And this recruitment was around in the late 1990s and early 2000s. What we knew was that the three-week regimen was actually radiobiologically lower dose. And therefore the results that we got, it wasn't surprising that the 40 Gy was actually gentler on the normal tissue. So that's an advantage for patients.

But what was surprising was it wasn't gentler on the tumor and non-inferiority was proven. So this suggests that overall treatment time is important for local control. So this fits with hypofractionation. Way back in 2009, 40 Gy in 15 fractions to both the breast and regional nodes became standard of care in the UK. But five-week nodal and actually breast as well remained standard of care in many countries for many years after that, a little bit to do with the fact that there were few patients treated in the START trial in terms of treating the node. So more recently we've had more randomized trials, particularly for nodal radiotherapy. And this includes the recently reported Danish SKAGEN 1 trial and also the French HypoG-01 trial, which was actually presented at ESMO in Barcelona a couple of weeks ago. So we've now got data for over 5,800 participants in really high-quality randomized trials testing three weeks and five weeks of nodal radiotherapy. And there's no statistically significant difference in late normal tissues for any of these, including lymphedema. So certainly, in my opinion and reflecting in many of the European guidelines, five-week radiotherapy is no longer indicated and three-week nodal radiotherapy is the international standard of care. So, in conclusion, the question is can we hypofractionate even further?

So the UK FAST-Forward trial tested three weeks with two different dose levels of one week for the whole breast. Primary endpoint was ipsilateral breast tumor response. More than 4,000 patients participated and this was reported in 2020 with a median follow -up of six years and this was very timely because this is a time of COVID and the results showed non-inferiority for local control with similar late normal tissue side effects and we've also had other results from the UK IMPORT HIGH trial which shows that we can safely deliver a small, highly targeted team of boost simultaneously with the whole breast in all in three weeks.

Finally, these two landmark trials have come together for the design of the UK FAST-Forward Boost Study led by my colleague Dr. Anna Kirby. And this is going to test three-week simultaneous integrated boost with two levels of one-week simultaneous integrated boost. And it's also going to test the safety of 5 fraction nodal radiotherapy, including the internal mammary node. Primary endpoint is ipsilateral breast tumor response, multiple normal tissue endpoints, including patient-reported outcomes of course, and the target recall is large with 4,800 participants. So, in summary, I would say that hypofractionation is efficacious, has similarly reduced toxicity. Importantly, it reduces patient burden and that's incredibly important because it means that people can get back on with their life quicker. It reduces health system costs, and also increases equity of access. So we really do need to continue to recruit and design high quality trials in this area.

Dr. Dionisia Quiroga: Thank you, Dr. Coles. I think you highlight that there really aren't any downsides to looking into hypofractionated radiotherapy at this point. So excited to see what those future trials yield.

And I want to thank you so much, Dr. Weber and Dr. Coles for sharing your valuable insights with us today on the ASCO Daily News Podcast.

Dr. Walter Paul Weber: Thank you very much.

Dr. Charlotte Coles: Thank you.

Dr. Dionisia Quiroga: And thank you to our listeners for joining us today. Our listeners will find a link to our guests’ article from the ASCO Educational Book in the transcript of this episode, as well as a link to their presentation from the most recent ASCO Annual Meeting. Finally, if you value the insights that you hear on the ASCO Daily News Podcast, please take a moment to rate, review, and subscribe wherever you get your podcast.

Disclaimer:

The purpose of this podcast is to educate and to inform. This is not a substitute for professional medical care and is not intended for use in the diagnosis or treatment of individual conditions.

Guests on this podcast express their own opinions, experience, and conclusions. Guest statements on the podcast do not express the opinions of ASCO. The mention of any product, service, organization, activity, or therapy should not be construed as an ASCO endorsement.

Find out more about today’s speakers: 

Dr. Dionisia Quiroga

@quirogad

Dr. Walter Paul Weber

Dr. Charlotte Coles

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Disclosures:

Dr. Dionisia Quiroga:

No relationships to disclose

Dr. Walter Weber:

Honoraria: MSD

Dr. Charlotte Coles:

No relationships to disclose