Management of Salivary Gland Malignancy Guideline

An interview with Jessica Geiger, MD, from Cleveland Clinic and Patrick Ha, MD, from the University of California, San Francisco, co-chairs on "Management of Salivary Gland Malignancy: ASCO Guideline." This guideline provides recommendations for preoperative evaluation, surgical procedures, radiotherapy techniques, the role of systemic therapy, and follow-up evaluations for patients with salivary gland malignancies. Read the full guideline at www.asco.org/head-neck-cancer-guidelines.

TRANSCRIPT

SPEAKER: 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. The mention of any product, service, organization, activity, or therapy should not be construed as an ASCO endorsement.

BRITTANY HARVEY: Hello, and welcome to the ASCO Guidelines Podcast series, brought to you by the ASCO Podcast Network, a collection of nine programs covering a range of educational and scientific content and offering enriching insight into the world of cancer care. You can find all the shows, including this one, at podcast.asco.org. My name is Brittany Harvey, and today I'm interviewing Dr. Jessica Geiger from Cleveland Clinic and Dr. Patrick Ha from the University of California San Francisco, co-chairs of management of salivary gland malignancy ASCO guideline. Thank you for being here, Dr. Geiger and Dr. Ha.

DR. PATRICK HA: Thank you, Brittany.

DR. JESSICA GEIGER: Thank you.

BRITTANY HARVEY: First, I'd like to note that ASCO takes great care in the development of its guidelines and ensuring that the ASCO conflict of interest policy is followed for each guideline. The full conflict of interest information for this guideline panel is available online with the publication of the guideline in the Journal of Clinical Oncology. Dr. Geiger, do you have any relevant disclosures that are directly related to this guideline?

DR. JESSICA GEIGER: No, I don't.

BRITTANY HARVEY: And Dr. Ha, do you have any relevant disclosures that are related to this guideline?

DR. PATRICK HA: No, I do not.

BRITTANY HARVEY: Thank you both. Then let's talk about some of the content of this guideline. So first, Dr. Geiger, can you give us a general overview of the purpose and the scope of this evidence-based guideline on the management of salivary gland malignancy?

DR. JESSICA GEIGER: Sure. So salivary gland cancers-- they're relatively rare, and they encompass a wide variety of both histologies, but also biologic behaviors of cancers. This is a very multidisciplinary tumor, so surgeons, radiation oncologists, pathologists, medical oncologists-- they all play an integral role in treating these patients. And the purpose of this guideline was to bring all of these disciplines together and to develop an as strong as possible, evidence-based way of approaching the diagnosis of such cancers and then approaching it from all modalities of therapy-- surgical, radiotherapy, systemic therapy-- in a very evidence-based and organized fashion.

BRITTANY HARVEY: Great, then as you just mentioned, this is a multidisciplinary guideline, and it covers six different subtopics on the management of salivary gland malignancy-- preoperative evaluation, surgical management, radiotherapy, systemic therapy, follow up, and treatment options for recurrent and metastatic disease. I'd like to go through and review the key recommendations from each of those sections for our listeners.

So first, Dr. Ha, what is the guideline recommend regarding preoperative evaluation for patients with salivary gland malignancy?

DR. PATRICK HA: Great, so I'd first like to start off by saying that we were focusing on salivary gland malignancy. So again, these are tumors where we may not know the diagnosis, but we're suspicious of this being cancer as opposed to a benign tumor.

So along those lines, there are many different imaging recommendations-- first off, that some sort of imaging would be helpful if there's a suspicion of cancer, and then drilling down a little bit more specifically if there is concern about bone involvement. And then CT scan was recommended if it was more of a concern about the soft tissue or perineural invasion or skull-based invasion, then MRI was suggested. And we did spend some time focusing on the strength of and the importance of tissue biopsies, either with fine needle aspiration biopsy or core needle biopsy as a real helpful tool to help clinicians determine what sort of procedures and care this patient might need.

Additionally, with the onset of more understanding of the pathology in the markers, it was felt that using these biopsies-- these FNAs or core biopsies-- to perform either molecular or immunohistochemical studies could further help clarify what the diagnosis would be and thus lead to sort of more specific and defined treatment subsequently.

BRITTANY HARVEY: And then following those evaluation and imaging and biopsy recommendations, what are the key surgical recommendations?

DR. PATRICK HA: Yeah, so again this is probably known to most people-- that when it is considered resectable, the surgery is really the mainstay upfront management option for these patients. We spent some time looking at the different types of surgeries and felt that it was a bit up to the discretion of the surgeon, but it depends on the location as to what type of surgery exactly needs to be done. But the idea is obviously we would want a complete resection of it and margins where possible.

And then we address the nodes and the ability for these cancers to sometimes spread regionally. And basically, if these are high risk or high grade cancers, specifically if there are things like the grade of the tumor itself-- the type-- and then whether there were other concerning features about it, than a neck dissection electively would be offered.

If there were N positive disease, then the neck dissection definitely should be performed. And then there was discussion as well about the facial nerve and how to manage that, wherein the evidence mostly reported trying to preserve the facial nerve whenever possible.

And then we did talk a little bit about the possibility of palliative resection, which can occur sometimes in the presence of distant metastatic disease upon presentation. And it was felt again that there is a palliative component to surgery if the metastatic disease didn't seem to be rapidly progressive or imminently lethal. So these are all the difficult decisions that we discussed regarding surgery.

BRITTANY HARVEY: OK, thank you. Then Dr. Geiger, how does this guideline address radiotherapy for patients with salivary gland malignancy?

DR. JESSICA GEIGER: Well, as Dr. Ha mentioned, this is primarily a surgical disease. So most of the recommendations regarding radiotherapy involve the post-operative setting. But if you look at the guideline, we have actually laid out 10 recommendations regarding radiation, and they're dependent on various factors with each cancer, so the histology of the disease, other tumor pathologic factors, such as T-stage, vascular, lymphatic invasion, margin status, perineural invasion-- all of that goes into the recommendation here. There's also considerations for what nodal basins to cover, based on where the tumor is, and even the type of radiation, and, of course, the timing of radiation. All of that is important to be considered, and all of those specific features are mentioned within the recommendations.

BRITTANY HARVEY: Great. And then in addition to those radiotherapy recommendations, what's the role of systemic therapy for patients with salivary gland malignancy?

DR. JESSICA GEIGER: Well, unlike the radiation section, where I said we have 10 specific recommendations, we're limited with the evidence for the use of systemic therapy in the curative setting of these diseases. So one point that I will make is, again, we're very limited based on evidence, and this is what is driving such a guideline-- is evidence, evidence, evidence. And we just don't have it.

There are several large studies that are ongoing, but until those results flesh out, we were limited. And so our recommendations are based on the lack thereof, and often are considered low quality or moderate strength of recommendation at best, based on our expert panel.

Basically, outside of a clinical trial, we're not recommending the addition of radiosensitizing chemotherapy with post-op radiotherapy. Again, that can be contentious, especially in the clinical realm, where there's a wide variety of biologic behavior. So some of the more aggressive diseases, we know that oncologists are advocating for the use of chemotherapy. But again, the evidence is not there yet, and so we weren't able to make that informative within this guideline.

And then we also addressed tumors that are expressing different markers, like androgen receptor, HER2, and make a recommendation for the use of targeted therapy, again noting a lack of evidence for it outside of a clinical trial currently.

BRITTANY HARVEY: OK, thank you for explaining the reasoning and the evidence behind those particular recommendations. So then for patients who have then completed treatment for salivary gland malignancy, Dr. Ha, what are the timelines and recommendations for follow up for these patients?

DR. PATRICK HA: Well, so again, this is where the data are really not strong. And so you'll notice that pretty much all of these recommendations were informal in consensus. But similar to the NCCN guidelines for general cancer follow up was believed by the panel that early follow up more frequently and just sort of spaced out over time was important.

And then there was an emphasis on some form of imaging often, whether that be CT or MRI, it's sort of up to the practitioner. And then perhaps for a couple of years after treatment, that might be important.

It was also felt that, as everyone probably knows, that one of the areas where this may spread to distantly is in the lung. So getting some sort of chest imaging between years 2 and 5 would be important as well, just in case one can detect an asymptomatic yet potentially treatable metastasis.

So again, a lot of informal consensus. The idea is that we feel it's important to continue to follow these patients to look for signs of recurrence, whether that's with imaging or physical exam. We thought that either would be an option.

BRITTANY HARVEY: Definitely. And the last section of recommendations for this guideline is on recurrent or metastatic salivary gland malignancies. So what are those treatment options, Dr. Geiger?

DR. JESSICA GEIGER: Well like before, when we're talking about systemic therapy, again, informal consensus is sort of driving the majority of these recommendations, again highlighting lack of strong evidence. That said, there are several different clinical situations that we address within these recommendations.

So whether a patient presents with diffusely metastatic disease with a large tumor burden or oligometastatic disease, where maybe just one or two local or regional areas have recurred. And so in that latter case, you could discuss with the patient is it worthwhile to do some locally ablative therapy, such as SBRT, or possibly a resection versus, for more widely metastatic disease, starting systemic therapy.

Now, there's also a recommendation specifically for the histology adenoid cystic carcinoma. And that is based on studies that have been done with tyrosine kinase inhibitors. And so there's some evidence for that outside of cytotoxic chemotherapy.

And then we also make a mention, which is very important, again on checkpoint inhibitors, but also on some of the targeted therapies-- doing next generation sequencing, looking for molecular markers that drive the progression of these diseases, and then in subsequent targeted therapies for this.

So we really try to encompass any and all particular situations that an oncologist may encounter with these diseases and offer some guidelines and recommendations regarding the appropriate management.

BRITTANY HARVEY: Great. Thank you both for reviewing those key points of the recommendations. This guideline goes through a lot of content, and so it's interesting to hear more about what kind of those details are for each section. So Dr. Ha, in your view, what is the importance of this guideline, and how will it impact clinicians?

DR. PATRICK HA: Well, I think that we realized we had a lot to cover in just a short amount of time. And I think that we felt that while the data may not be as strong with-- full of randomized clinical trials as perhaps other disease subgroups, we felt it was important to organize what the current state of the data are, because these are rare cancers, and there are some nuances between some of the histologies even that it may be difficult to keep up to date all the time. So organizing it into one document where it we have clearly delineated what areas we feel are common practice amongst experts and what areas actually do have some studies and perhaps some deeper level of understanding and depth of studies would be important, so that clinicians understood where it was that they have to be a little more creative and areas where they felt like hey, we feel like this is important to do.

So I think that that would be useful for clinicians. And I think also it provides a framework for future studies, meaning that we hope that whenever these get updated and 5 or 10 years that there will be more studies. But it also does, I think, help for those of us who are in the field to organize where those gaps are so you can look at the guidelines and really understand OK, these are the areas that we need better understanding of how to treat patients.

BRITTANY HARVEY: Definitely. It's helpful to understand both where there is evidence and where there is no evidence and where informal consensus takes rule. So then finally, Dr. Geiger, how will these guideline recommendations affect patients?

DR. JESSICA GEIGER: Well, when it comes to cancer treatment, there is a lot of fear in the unknown. And I feel that patients are always asking am I doing the right things? Am I looking to make sure that I'm getting the best of care? And I think with any guideline-- this one included-- patients can rest assured that they don't have to make the trip and travel to a large academic center necessarily-- that they can feel comfortable knowing that their providers are following the data and following such guidelines that have been brought forth in one single document. Even though the patients aren't going to necessarily have this document at hand, they can have confidence within their oncology team.

And then I think they'll also benefit from, as Dr. Ha was saying, as medical professionals being able to identify gaps and bring forth clinical trials. That's the only way that we're going to be able to move this field forward, particularly in such a rare disease that many histologies as salivary gland malignancies. And so while being treated in a regional oncology office or a community oncology office, maybe their provider will then recommend clinical trials that are open and have that additional opportunity for patients, if they so desire. So knowing that they're getting great standard of care based on evidence, but then also the opportunity to create new evidence for us to better treat patients in the future.

BRITTANY HARVEY: Definitely. Well, I want to thank you both so much for your work on developing these evidence-based guidelines and for taking the time to speak with me today on the podcast, Dr. Geiger and Dr. Ha.

DR. JESSICA GEIGER: Thanks.

DR. PATRICK HA: Thank you.

BRITTANY HARVEY: And thank you to all of our listeners for tuning into the ASCO Guidelines Podcast series. To read the full guideline, go to www.asco.org/head-neck-cancer-guidelines. You can also find many of our guidelines and interactive resources in the free ASCO Guidelines app, available on iTunes or the Google Play store. If you have enjoyed what you've heard today, please rate and review the podcast, and be sure to subscribe so you never miss an episode.