Diagnosis and Management of Squamous Cell Carcinoma of Unknown Primary in the Head and Neck Guideline

An interview with Dr. Jessica Geiger from Cleveland Clinic on "Diagnosis and Management of Squamous Cell Carcinoma of Unknown Primary in the Head and Neck: ASCO Guideline." This guideline provides evidence-based recommendations addressing diagnosis, surgery, radiation therapy, and systemic therapy for patients with squamous cell carcinoma of unknown primary in the head and neck. Read the full guideline at www.asco.org/head-neck-cancer-guidelines.

Transcript

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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 podcasts.asco.org. My name is Brittany Harvey, and today I'm interviewing Dr. Jessica Geiger from Cleveland Clinic, author on Diagnosis and Management of Squamous Cell Carcinoma of Unknown Primary in the Head and Neck ASCO guideline. Thank you for being here, Dr. Geiger. Thanks, Brittany, for the invitation and the opportunity.

First, can you tell our listeners what is squamous cell carcinoma of unknown primary in the head and neck and what this guideline generally covers?

Sure. So cancer of unknown primary or carcinoma of unknown primary in the head and neck is metastatic squamous cell carcinoma found in cervical lymph nodes. And importantly, there's a lack of a primary mucosal tumor that's identified. So these patients comprise about 5% of all head and neck cancers. And it poses a challenge for all members of the treatment team, both from a diagnostic perspective but as well as treatment management; what is the best way to proceed for treatment with these patients? Now this guideline provides an up-to-date and evidence-based management for recommendations. And these recommendations are based on published literature. But where the data is lacking in the literature, expert panel consensus was utilized to provide recommendations. I'd like to discuss some of the key recommendations of this guideline. First, with regard to diagnosis of squamous cell carcinoma of unknown primary in the head and neck, what are the challenges, and what are the recommendations from the guideline?

The diagnostic challenges come about when a patient presents with a neck mass. They often have imaging, a clinical exam. But again, about 3 to 5 percent of patients, we will be unable to locate where this tumor started. Squamous cells don't show up in the lymph nodes by themselves. They came from somewhere else. And part of the reason that this makes a diagnostic challenge if we're not able to readily see where the primary tumor is, oftentimes, it's very small in size. And so it's not picked up by imaging or by a physical exam. Also, these are sometimes difficult anatomic locations to evaluate. So all of this can pose a challenge to coming up with the right diagnosis. Now some of the recommendations for diagnosing these patients, obviously, we need to have a complete history and physical exam. And this physical exam should include a fiberoptic laryngoscopy, so a good lab endoscopy exam looking at all of the mucosal tissues, trying to find abnormalities, trying to see where exactly this cancer started. Now in order to make the diagnosis of squamous cell carcinoma, obviously, a biopsy needs to be done, and that is in the neck, where these suspicious nodes are. Either a fine needle aspiration or a core needle biopsy is recommended within these guidelines. The guidelines also indicate when to do additional pathologic testing. So this is for high-risk HPV, especially in neck nodes that are in level two or three. If high risk HPV testing is negative, then we give recommendations regarding Epstein-Barr virus testing, so looking to find is this nasopharynx primary cancer and then, of course, imaging guidelines. So the image modality of choice is a contrast enhanced CT of the neck, not just to elucidate and better evaluate the nodal burden of disease, which the patient presents with, but also to investigate for evidence of a mucosal primary. Now if that fails to produce a primary then we give recommendations regarding PET scans.

And then what are the recommendations for surgery for a squamous cell carcinoma of unknown primary in the head and neck?

There are many recommendations that we go into to address the surgical approach to a cancer with unknown primary. Now the previous question asked about diagnosis included in the surgical recommendations in our guidelines for diagnostic surgical interventions. So we can sort of branch point or divide recommendations for surgery, whether it's a diagnostic or a therapeutic procedure. And then in the therapeutic procedures, we can look more in detail at what surgery is recommended for a primary or the mucosal, and then how to how do we address the neck? So first, as part of diagnosis with surgery, all patients need a complete operative evaluation of the upper aerodigestive path. And this includes directed biopsies. So the surgeon goes in the operating room, gets a good look around. Any suspicion for any possible cancer is biopsied, as opposed to blind biopsies or random biopsies, which are not recommended.

Now the recommendations for surgery also include when to do tonsillectomies and what tonsillectomies to do. So are these palatine tonsillectomies or lingual tonsillectomies? Do we perform them or recommend them on the ipsilateral side, or what is the role for a contralateral or even bilateral tonsillectomy? And I won't go into the specifics because they're all-- all the different scenarios are laid out within the guidelines, but the recommendations are based on the patient's nodal burden. So do they have bilateral lymph nodes; do they have lymph nodes just on one side; how big they are, that all plays a role into the recommendations regarding surgical intervention. Now if mucosal primary tumor is identified, there are clear recommendations and guidelines that every effort to clear the disease with negative margin is of paramount importance. So we're talking about a definitive oncologic surgery in this case. And the reason we want to stress that negative margins are the goal is because we're trying to avoid trimodal therapy. So we're trying to get to a good surgical resection. A positive margin left behind is likely going to lead to recommendations for postoperative radiation with the addition of radiosensitizing chemotherapy, which is what we do not want. We want to try to avoid toxicities with trimodal therapy.

That brings me to then surgical management of the neck and the guidelines set forth in this document. So recommendations for neck surgical management are broken into whether the patient has what we consider small volume disease versus large volume disease. So for small volume disease, small lymph nodes on one side of the neck, we recommend a multidisciplinary discussion whether or not the patient should be best served with a definitive surgery involving a neck dissection or if they should have definitive radiotherapy. Again, our goal is to avoid trimodal therapy. So if there's obvious gross extranodal extension seen on imaging, then they would be best served with a primary radiation approach, as opposed to surgical. Similarly, any large volume disease, obviously, gross extranodal or extracapsular extension, definitive chemo radiotherapy is favored. Now a comment on management of the neck, if you're suspecting an oropharynx primary, which is the majority of cancer of unknown primaries of the head and neck, we give specific recommendations regarding what levels to routinely surgically dissect, levels IIa, III, and IV in that instance.

In your discussion of the surgical recommendations, you began to touch on the radiation recommendations. Could you elaborate on those recommendations from ASCO on radiation therapy for this patient population? Of course. And again, when you refer back to the guideline and the recommendations, there are even more specific recommendations regarding when and how to use primary radiotherapy or adjuvant radiotherapy in this setting. So I'm not going to go into great detail for every single recommendation that is provided, but a nice overview is, basically, if a patient is receiving radiotherapy as the primary definitive management of cancer of unknown primary, obviously, we recommend treatment should be given to gross nodal disease but also to neck regions and mucosal anatomic regions, which are considered at risk for containing microscopic disease. So it's not just good enough to radiate what we see on imaging but also to consider the areas around it, the nodal echelons and other mucosal areas where there could be cancer. So for example, an HPV-related disease where it's likely oropharynx unilateral disease, there are specific locations to include. And this is also the same for HPV-negative disease. Now if we're worried about a possible nasopharynx cancer in the setting of E-Barr or EBV-positive disease, the mucosal radiotherapy can be limited to just the nasopharynx, but you want to radiate bilateral necks, level II through IV, and include the retropharyngeal lymph nodes.

There are specific recommendations where unilateral versus bilateral neck irradiation is recommended. And again, I just encourage the listeners to refer back to the guideline itself for these specific instances. Also included within the radiotherapy guidelines and recommendations are specific doses. What doses do you use? Where do you use these doses? And these doses are extrapolated from known and well established evidence for traditional head and neck squamous cell carcinoma in which we know where the primary is, also, when to give post neck dissection kind of in the adjuvant setting, again, all extrapolated from known head and neck squamous cell carcinoma but very specific and laid out within the guidelines.

And what does the expert panel recommend for systemic therapy for squamous cell carcinoma of unknown primary in the head and neck?

Similarly, when we devised the recommendations for radiotherapy for this disease, the use of systemic therapy, when to use it, when to add it to radiation is also extrapolated from the head and neck guidelines and evidence for known head and neck cancer. So we recommend adding chemotherapy to definitive radiotherapy in advanced nodal disease, and we've defined what advanced nodal disease is based on the AJCC 8th Edition. So in HPV-negative disease, this is N2 or N3, in HPV-positive disease, multiple ipsilateral lymph nodes. If a lymph node is greater than three centimeters, we recommend adding chemotherapy to radiation in the definitive setting. Now, specifically, the chemotherapy that we recommend is cisplatin. Again, this is based on well-established studies and evidence in head and neck cancer. So patients who are medically fit and able to receive cisplatin, that is the treatment of choice. There are also recommendations regarding resected cancer of unknown primary. So with evidence of extranodal capsular extension, we recommend the addition of, again, cisplatin chemotherapy to postoperative radiotherapy, again, extrapolated from well-established head and neck studies. And then, again, if you are concerned that this is an Epstein-Barr-related nasopharynx cancer, stages II through IVA, again, AJCC 8th Edition, we recommend the addition of chemotherapy to radiation in those settings as well.

Great. This guideline covers a lot of ground and many recommendations. Can you speak to why this guideline is important and how you envision it will impact practice? So this guideline is important because a fair amount of patients will be presenting with cancer of unknown primary. We stress through this guideline that this is very evidence-based recommendations and guidelines with a focus on a multidisciplinary approach to how to treat these patients.

And finally, how will these guideline recommendations affect patients?

Well, hopefully, this guideline will provide reassurance to patients that no matter where they are receiving treatment, they are receiving quality standard of care management, again, largely driven by evidence. And it doesn't matter whether they're treated by locally practicing experts and specialists or at a large institution, they're being treated by the standard of care that is accepted across the board.

Well, thank you for your time today, Dr. Geiger, and for working on these comprehensive guidelines. You're very welcome. Thanks, Brittany.

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 and iTunes or the Google Play Store. If you have enjoyed what you've heard today, please write and review the podcast and be sure to subscribe so you never miss an episode.