Proton Therapy Case Study – Sinonasal Cancers

Published in Clinical Connection - Spring 2025

Sinonasal cancers represent a very challenging disease site to treat due to its location. Often, the cancer directly invades or is in close proximity to critical structures such as the brainstem, optic nerves, minor salivary glands, mucosal sites in the nasopharyngeal region, and temporal lobes in the brain. Patients typically present with persistent nasal obstruction or congestion, nose bleeds, runny nose, changes in vision or smell, headaches, facial pain, bulging eye, or chronic sinus infections. Some patients do not have any symptoms at all.

Patient Presentation

A 50-year-old female initially presented with left eye swelling and tearing. Imaging showed a 4 cm mass which involves nasolacrimal duct with contiguous extension to the left orbit. Biopsy showed HPV-associated squamous cell carcinoma. She underwent orbital exenteration with pathology showing pT4N0 HPV positive squamous cell carcinoma with close margins. She underwent postoperative radiotherapy with a mixed proton/photon plan.

Treatment

Early studies have suggested that proton radiotherapy yields improved outcomes in sinonasal cancer compared with photon radiotherapy; however, the results are not clear-cut and should be interpreted with caution as sinonasal cancer encompasses a diverse group of neoplasms with different radiobiological characteristics (Patel, Samir H., et al. "Charged particle therapy versus photon therapy for paranasal sinus and nasal cavity malignant diseases: a systematic review and meta-analysis." The Lancet Oncology 15.9 (2014): 1027-1038.). Patients with slower growing pathologies (such as minor salivary gland tumors or olfactory neuroblastomas) likely benefited from the higher relative biological effectiveness (RBE) of proton radiotherapy. Regardless of the pathology, patients may benefit from certain dosimetric advantages with proton planning in an attempt to reduce integral dose to critical organs-at-risk such as the hippocampus, salivary glands, brainstem, optic nerves and other important structures within the head and neck. In certain scenarios*, the Johns Hopkins team of clinicians, physicists and dosimetrists carefully undertake comparative planning with proton and photon radiation treatment and may recommend a mixed proton/photon plan to take advantages of both planning techniques.

*Side effect profile for protons vs photons are highly dependent upon individual anatomy and scenario. Depending on the scenario, your provider may recommend proton, photon, or a mixed proton/photon plan. Please discuss with your provider for tailored-made recommendations in your specific scenario

 

Assessing the Benefits of Proton Therapy

For this patient, a plan comparison was assessed for both target coverage and the ability to safely limit radiation dose to critical structures and healthy tissues. The comparison of dose distributions between proton and photon therapies revealed significant differences. While proton planning helped to significantly reduce dose to the brain, hippocampus (responsible for memory and learning) and to the salivary glands (xerostomia, or dry mouth, can result in taste changes and dental decay), photon planning helped to limit dose to the lips and soft palate which can result in painful mucositis. Utilizing a mixed proton/photon plan allowed us to achieve adequate tumor control while achieving better sparing of critical structures.

Patient experience

The patient received a biological equivalent dose of 65.1 cobalt Gy delivered over 30 treatment fractions of proton radiation over 6 weeks. No additional systemic therapy was given. The patient tolerated the treatment well with limited toxicities and is now being seen for routine follow up visits.

Scans of a patient's head showing sinonasal cancer and the effect of integral dose to the brain and hippocampus with protons

Scans of a patient's head with sinonasal cancer showing the effect of integral dose to the contralateral submandibular with protons

Scans of a patient's head with sinonasal cancer showing the effect of integral dose to the ipsilateral parotids with protons.

Scans of a patient's head with sinonasal cancer showing lip and palate dose with protons.

Proton Therapy Central Nervous System Cancer Experts

To refer a patient or find out more about the Johns Hopkins Proton Therapy Center, visit hopkinsproton.org.

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