Takeaway from Multidisciplinary 2020 Head and Neck Cancers Symposium

A dosimetric comparison of proton versus photon irradiation for pediatric glomus tumor – Vidal et al.

👉 Most notable are the lower doses to ipsilateral (left) cochlea, right-sided structures, and expanded cord with the proton plan. The mean oral cavity dose was also significantly lower. 
Dosimetric superiority of protons in the skull base region is largely due to the absence of dose deposition distal to the target, or “exit dose”. This phenomenon is explained by the distinctive Bragg Peak that protons have which allows for a rapid fall-off of the irradiation dose beyond the target. Contralateral structures were significantly spared with the proton plan. As previously established, proton beam therapy remains the therapy of choice for pediatric patients given their long term survival and concerns for secondary malignancy, as well as lower doses to most if not all normal structures of interest.

Long-Term Update of Proton Beam Re-Irradiation for Recurrent Head and Neck Cancer – Lee et al.

👉 Proton Therapy re-irradiation of the head and neck provides effective tumor control with acceptable acute and late toxicity profiles, likely secondary to the decreased dose to surrounding normal, albeit previously irradiated tissue.

Proton Therapy for Non-Skull Base Head and Neck Adenoid Cystic Carcinoma – Lee et al.

👉 Proton Therapy is a feasible option for ACC for the non-skull based head and neck in the definitive and postoperative setting, offering low rates of acute and late toxicities. Patients with metastatic disease also had acceptable outcomes and local treatment was well tolerated.

Improved Outcomes by proton beam radiation for nasal cavity and paranasal sinus malignances – Fan et al.

👉 Proton Therapy offers durable local control and survival in patients with nasal cavity and paranasal sinus malignancy. Even patients with recurrent tumor or with prior radiation history could achieve encouraging outcomes.

Chemosensory Outcomes in Nasopharyngeal Cancer Patients Treated with Proton Beam Therapy: A Prospective Longitudinal Study – Slater et al.

👉 with Proton Therapy the long-term chemosensory outcomes are preserved.

Proton Therapy for Nasopharyngeal Cancer: A Matched Case-control Study of Intensity-Modulated Proton Therapy and Intensity-Modulated Photon Therapy – Li et al.

👉 IMPT showed dosimetry advantages over  IMRT and lower rates of acute toxicities while both had comparable  treatment outcomes.

Outcomes following Proton Therapy for Squamous Cell Carcinoma of the Larynx – Ausat et al.

👉 Proton Therapy for SCC of the larynx demonstrates a high rate of overall survival, local-regional control, and disease-free survival with low toxicity profile.

Outcomes of Major Salivary Gland Tumors Treated with Proton Beam Radiation Therapy – Zakeri et al.

👉 rates of locoregional control were high and treatment was well tolerated.

Intensity Modulated Proton Therapy (IMPT) to the Parotid
Gland: A Seven-Year Experience – Hanania et al.

👉 IMPT for treatment 724 of the parotid gland manifests in low rates of acute and chronic toxicity 725 while maintaining dosimetric coverage and high rates of biological control. 726 Skin V30 may predict for radiation dermatitis.

Redefine End-of-range RBE of Protons Based on Long-term Clinical Outcome – Zhan et al.

👉 RBE in brain is 1.18

Abstracts published in International Journal of Radiation Oncology • Biology • Physics, Volume 106, Issue 5, April 1, 2020

https://www.redjournal.org/issue/S0360-3016(20)X0004-6


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We could tell you the story of Zahra, a 6-year old girl from Bahrain diagnosed with a medulloblastoma.

We could detail her pathology and the treatment plan agreed with her local medical team.

We could report the heartbreaking words from her family.

We could depict the efforts by the Ministry of Health and US Embassy Teams to have her traveling as soon as possible.

We could relate her journey to Hampton.

We could talk about the exams and procedures she underwent.

We could narrate how we’ve struggled to get her chemotherapy in short-supply.

We could elaborate on the benefits of Proton Therapy over other treatment modalities in her case.

But we can’t describe the love we share with our patients.

Zahra has elected Walter, our Anesthesia Nurse, as her new best friend.  They’re walking together along the corridor to fetch  Zahra’s anesthesia stretcher. They come from different countries, 50 years separate them, they don’t speak a common language, and yet they truly love each other.

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Proton therapy: the current status of the clinical evidences – by Dongryul Oh

Precision and Future Medicine 2019

Proton Therapy Clinical Evidences – Dongryul Oh

The dosimetric advantages of proton therapy—compared with photon therapy—have been clearly defined in many comparison studies involving various tumor sites. There are now accumulating clinical data demonstrating that this dosimetric advantage can lead to better outcomes such as reduced RT toxicity and improved treatment outcomes. 

Pediatric Tumors

RT has an important role in treating pediatric tumors including central nervous system (CNS) tumors, extra-cranial sarcomas, neuroblastoma, and hematopoietic tumors. Long-term toxicities, including secondary malignancies, neurocognitive dysfunctions, growth and musculoskeletal problems, and cardiac problems, are major concerns in pediatric patients who undergo RT. There have been many efforts to reduce the RT dose and volume to avoid these RT-related toxicities.

Proton therapy is one of the best options to reduce unnecessary irradiation dose and volume in pediatric patients.

More than 30 pediatric tumor types were treated, mainly with curative intent: 48% were CNS, 25% extra-cranial sarcomas, 7% neuroblastoma, and 5% hematopoietic tumors

Head and Neck Tumors

Retrospective data have demonstrated better local control (LC) and overall survival (OS) with proton therapy than with photon therapy including IMRT and stereotactic body radiation therapy (SBRT).

Proton therapy has also demonstrated better survival rates in nasal cavity and paranasal sinus tumors.

In oropharyngeal cancers, proton therapy can reduce toxicity to normal tissues.

Proton therapy can also reduce toxicities in unilateral irradiation, such as in cases involving major salivary gland tumor and oral cavity cancers, because the exit dose of the proton beam is essentially negligible

CNS tumors

Cognitive impairment has been one of major concerns following RT for CNS tumors. Proton therapy has a potential benefit to reduce the irradiated dose to normal brain tissue to prevent cognitive dysfunction. In addition, a dose escalation could be possible in radioresistant brain tumors such as high-grade gliomas.

Gastrointestinal tumors

Proton therapy can spare the surrounding normal tissues when it is used to treat gastrointestinal tumors. In the management of hepatocellular carcinoma (HCC), it is very important to spare liver function. Because the liver is an organ with parallel functional subunit in the model of radiation response of normal tissues, liver toxicity is more sensitive to irradiated volume. Proton therapy has a major advantage in reducing the irradiated volume of remnant liver when irradiating the tumor. In many retrospective trials, proton therapy resulted in favorable outcomes.

Re-irradiation

Proton therapy has the advantage of irradiating the target while reducing the dose to the surrounding normal tissues; thus, it has a potential benefit in re-irradiation. Many retrospective studies investigating re-irradiation in various tumor sites have been reported.

Non-Small Cell Lung Cancer

Low-dose shower is a major risk for radiation pneumonitis (RP) when treating non-small cell lung cancer (NSCLC) with photon therapy. If the lateral beam placement is avoided to reduce the lung dose, the irradiated dose to heart is consequently increased and results in increased cardiac death in long-term follow-up. In many dosimetric studies, proton therapy demonstrated advantages in lung and heart dose compared with photon therapy. Several clinical studies have reported treatment outcomes and toxicities of proton therapy in early-stage disease, locally advanced disease, re-irradiation, and in postoperative settings 

Indications for Proton Therapy

American Society for Radiation Oncology (ASTRO)  has updated the recommendations for insurance coverage. The ASTRO recommendation is based on four selection criteria:

  1. a decrease in dose inhomogeneity in a large treatment volume is required to avoid an excessive dose “hotspot” within the treated volume to lessen the risk for excessive early or late normal tissue toxicity;
  2. the target volume is in close proximity to ≥1 critical structure(s), and a steep dose gradient outside the target must be achieved to avoid exceeding the tolerance dose to the critical structure(s);
  3. a photon-based technique would increase the probability of clinically meaningful normal tissue toxicity by exceeding an integral dose-based metric associated with toxicity;
  4. and, finally, the same or an immediately adjacent area has been previously irradiated, and the dose distribution in the patient must be carefully modelled to avoid exceeding the cumulative tolerance dose to nearby normal tissues.

Based on the above medical necessity requirements and published clinical data, group 1, which is recommended coverage is listed as follows:

  • ocular tumors, including intraocular melanomas;
  • skull base tumors, primary or metastatic tumors of the spine, where spinal cord tolerance may be exceeded with conventional treatment or where the spinal cord has previously been irradiated;
  • hepatocellular cancer;
  • pediatric tumors;
  • patients with genetic syndromes making total volume of radiation minimization crucial;
  • malignant and benign primary CNS tumors;
  • advanced and/or unresectable H&N cancers;
  • the paranasal sinuses and other accessory sinuses cancers;
  • non-metastatic retroperitoneal sarcomas;
  • and cases requiring re-irradiation.

Read the full study on Precision and Future Medicine 2019

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