Improving Imaging Guidelines for Extranodal Extension in Head and Neck Cancer

Microscopic photorealistic image of tumor cells - Generated with Adobe Firefly

Extranodal extension is a significant prognostic factor in head and neck cancer. While imaging plays a crucial role in detecting extranodal extension, current guidelines often rely on clinical findings and may not accurately capture more subtle cases.

A study published in The Lancet Oncology aimed to develop a consensus-based grading system for imaging-detected extranodal extension inhead and neck cancer to improve diagnostic accuracy and standardization.The proposed guidelines recommend using the following criteria to identify imaging-detected extranodal extension in head and neck cancer:

• Indistinct or irregular nodal margin or border
• Extension into perinodal fat
• Extension into adjacent structures
• Conglomerate, matted, and coalescent nodes

The guidelines also recommend that the following factors should not be considered when determining the presence or absence of imaging-detected extranodal extension:

• Distance of invasion into perinodal fat.
• Type or number of sites of involved adjacent structures.
• Specific number of nodes involved.

In an interview with Targeted Oncology^TM, Christina Henson, MD, radiation oncologist at the University of Oklahoma, discussed the study, proposed guidelines, and how she sees them affecting practice for physicians and patients.

Targeted Oncology: What are the current imaging guidelines in head and neck cancer?

Christina Henson, MD

Henson: Most patients with head and neck cancer are going to get a CT scan and usually a PET scan before they start treatment. The focus of the paper is on a specific finding on imaging, which is extranodal extension. The way that the [National Comprehensive Cancer Network (NCCN)] guidelines are written, and the way that they are practiced at most centers that follow the NCCN guidelines, is that a clinical diagnosis of extranodal extension is not supposed to be made in the absence of major, obvious clinical findings. But you would not need imaging to diagnose a fixed mass in the neck that is tethered to muscle or bone or is causing major nerve dysfunction. Right now, we are only supposed to call extranodal extension on imaging if 1of those other clinical findings is present as well. The more subtle cases, which is a much larger proportion of the cases, go undiagnosed until surgery.

What was this study investigating?

We have realized that people are wanting better guidelines for calling extranodal extension on imaging. There have been a handful of sets of guidelines proposed, but none of them have been widely adopted. As more people are getting minimally invasive surgeries for head and neck cancer or are opting for organ preservation, it is important to be able to diagnose this feature in its subtler instances. That was the prompting for doing this project, to get a big pool of expert head and neck radiologists representing all the major oncology cooperative groups and query them on these different things and see where they stood to come up with the consensus guidelines so that everything is cohesive.

What guidelines are you proposing?

There are 4 grades of extranodal extension that that came out of this paper, and they are based on imaging findings ranging from subtle lack of clarity around the border of a lymph node or small speculations ranging all the way to those more clinically overt instances, including things that previously, radiologists would say that they were pretty sure it was extranodal extension but would not be extreme enough that it met the NCCN guidelines. [For example], clusters of lung nodes that appear matted together now that will be able to be called extranodal extension and one of the grades that we have proposed.

How do you see these guidelines changing practice?

There is some discussion of potentially incorporating these grading criteria into the next iteration of the NCCN guidelines. That would be great, because everyone pretty much uses the NCCN guidelines, and that would mean that everyone is using the same scoring system. Going forward, we will be able to evaluate this grading system better because everyone will be using it in the same way. That is an important part of being able to validate a new tool. It will be helpful to have this framework as well for better communication, clarity, and standardization in clinical trials.

The biggest way we think this will affect patients is with the increased use of transoral robotic surgery [TORS] for [human papillomavirus (HPV)]-related oropharyngeal cancer. We try to avoid offering TORS to patients who have extranodal extension. But again, we do not have the tools to call those more subtle varieties of extranodal extension. A lot of times, those patients will go to surgery, then they are found to have extranodal extension after the fact on pathology, meaning that then they must get chemo[therapy] and radiation after surgery, whereas they probably should have been treated with chemoradiation upfront and avoided surgery. Now they have been treated with 3 different modalities with 3 different sets of toxicities.

REFERENCE:

Henson C, Abou-Foul AK, Yu E, et al. Criteria for the diagnosis of extranodal extensiondetectedon radiological imaging in head and neck cancer: Head andneck cancer international group consensusrecommendations. Lancet Oncol. 2024;25: e297-307. doi:10.1016/S1470-2045(24)00066-4