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An Ounce of Parotid Prevention: Improving Radiation-Related Toxicity for Head & Neck Cancer with Metabolic Imaging Biomarkers

July 12, 2021

Last month we discussed hypofractionated treatment effects (HyTEC) including a need for new techniques to minimize toxicities. One of the most common normal tissue complications in radiation oncology is dry mouth (xerostomia) after head and neck cancer (HNC) radiation treatment (RT).

For the July 2021 #RadOnc #JC from Saturday, July 17th 8AM CST to Sunday July 18th 1PM CST (live hour) we will explore newer technologies to better understand and prevent this toxicity and others through a recent paper:

Elhalawani, H., et al. (2021). “(18)FDG positron emission tomography mining for metabolic imaging biomarkers of radiation-induced xerostomia in patients with oropharyngeal cancer.” Clin Transl Radiat Oncol 29: 93-101.

The article is Open Access, thanks to the study authors, Elsevier, and ctRO.1
Authors Drs. Clifton Fuller (@CD_Fuller), Hesham Elhalawani (@HElhalawaniMD), Carlos Cardenas (@CarlosMedPhys) and other guests will be joining us!

A Parotid Problem
During most HNC radiation treatments (RT) the salivary glands receive larger volumes of higher radiation doses. This includes the parotids that produce the majority of saliva. This often causes long-term damage. Over 50% of HNC patients have oral disorders after RT that impair quality of life. The usual thin secretions created by normal salivary glands becomes thick and acidic after salivary gland damage. This causes oral discomfort, trouble speaking, altered taste, and eating difficulties that can lead to oral infections and weight loss months-to-years after treatment. 

The Prevention Paradigm

Common supportive management techniques include dietary changes and strict oral hygiene, chewing gums, sprays, mouthwashes, and therapy for speech and swallowing.  However, these have limited effectiveness.  A newer paradigm is preventing salivary gland damage before it occurs.

Older techniques used 3D conformal radiation treatment (3DCRT) with larger fields than newer intensity modulated RT (IMRT) that can selectively spare normal parotid glands. Studies including PARSPORT2 and RTOG 00223 suggest IMRT reduces xerostomia by half, but ~30-50% of patients still have significant xerostomia and reduced salivary production.  The radioprotector amifostine (WR-2721) showed benefit, but its impact on tumor control is still questionable4 while surgery with transfer of the submandibular gland can prevent xerostomia, but only in very select patients5.

Is Newer Technology A Solution?
The increased availability of metabolic imaging with PET-CT, data storage, and computer processing power enables newer ways to study damage to the parotid glands to help prevent xerostomia.  The chosen paper by Elhalawani et al suggested a new workflow to assess radiation-related toxicities using ‘metabolic imaging biomarkers’ (MIBs) with PET-imaging. Combined with radiation dose and other traditional clinical variables a new model of normal tissue complication was created.1 

Can this newer molecular imaging biomarker prevent xerostomia and other side effects for head and neck cancers and others?

Please join us at the #RadOnc #JC this weekend to discuss this and more.

Starts 8 AM CST Saturday July 17th (with an asynchronous portion)
until live hour 1-2 PM CST Sunday, July 18th, 2021.

With a focus on the following topics:

T1.  Background/Aims: What is standard practice for HNC treatment, PET-CT use, and predictive models in your region?  Why do we need better models for xerostomia and other normal tissue complications for Head and Neck and other cancer treatment? Why are newer biomarkers like those from PET-CT helpful?  

T2.  Methods & Model Development: What were the methods of this study? How was the biomarker-based model developed? What can be used to assess its validity?

T3.  Results/Discussion: What were the model results using clinical, dosimetric, and metabolic imaging features? How can this improve on other models for assessing normal tissue toxicity? Can this be used to reduce dry mouth and other toxicities for HNC and other cancer treatments? Will this change your practice?

T4. #PatientsIncluded:  What is important for patients undergoing radiation treatment for HNC?  Can this be used to improve on our models and other tools for shared decision-making?

T5. Next Steps: What is still needed for biomarkers to be used in daily practice for HNC?

Tips to participate:

  • Guidelines on how to sign up & participate
  • Disclaimer for ways to keep #RadOnc #JC rewarding and professional. If you’re not ready, just lurk & tune in to the conversation.
  • Just don’t forget the #RadOnc #JC tag!

Suggestions? Leave a comment or tweet us at @Rad_Nation. And please join us this weekend!

-Dry Mouth/Xerostomia (ASCO):

-Head and Neck Cancers (RT Answers):
-What is PET-CT? (ASCO):


1. Elhalawani H, Cardenas CE, Volpe S, et al. (18)FDG positron emission tomography mining for metabolic imaging biomarkers of radiation-induced xerostomia in patients with oropharyngeal cancer. Clin Transl Radiat Oncol. Jul 2021;29:93-101. doi:10.1016/j.ctro.2021.05.011

2. Nutting CM, Morden JP, Harrington KJ, et al. Parotid-sparing intensity modulated versus conventional radiotherapy in head and neck cancer (PARSPORT): a phase 3 multicentre randomised controlled trial. Lancet Oncol. Feb 2011;12(2):127-36. doi:10.1016/s1470-2045(10)70290-4

3. Eisbruch A, Harris J, Garden AS, et al. Multi-institutional trial of accelerated hypofractionated intensity-modulated radiation therapy for early-stage oropharyngeal cancer (RTOG 00-22). Int J Radiat Oncol Biol Phys. Apr 2010;76(5):1333-8. doi:10.1016/j.ijrobp.2009.04.011

4. Brizel DM, Wasserman TH, Henke M, et al. Phase III randomized trial of amifostine as a radioprotector in head and neck cancer. J Clin Oncol. Oct 1 2000;18(19):3339-45. doi:10.1200/jco.2000.18.19.3339

5. Wu F, Weng S, Li C, Sun J, Li L, Gao Q. Submandibular Gland Transfer for the Prevention of Postradiation Xerostomia in Patients with Head and Neck Cancer: A Systematic Review and Meta-Analysis. ORL. 2015;77(2):70-86. doi:10.1159/000371854

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