Intensity-Modulated Neutron Therapy (IMNT) for Head and Neck Cancer: Early Toxicity Outcomes

PURPOSE/OBJECTIVE(S)

Locally advanced head & neck cancers (HNC) are challenging to treat due to abutment of critical, dose-limiting structures. Fast neutron radiotherapy (NT) is a high linear energy transfer (LET) modality that provides better local control than photons for radioresistant cancers such as salivary gland tumors, but there have been concerns of toxicity with 3D conformal neutron therapy in the past. Recent technological advances have enabled the planning and delivery of IMNT, which improves target conformality and may reduce toxicity compared to 3D conformal NT. We report the first clinical evaluation of early toxicity outcomes of IMNT for HNC.

MATERIALS/METHODS

Study is a single-institution retrospective review of all HNC patients treated with curative-intent IMNT from 10/2022 to 2/2023, using a hospital-based cyclotron (50.5 MeV 1H+ beam incident on a Be target) equipped with an isocentric gantry and multileaf collimator (MLC). A commercial treatment planning system with custom neutron-specific scattering kernels was used for IMNT planning using 4-6 fields. Patient-specific quality assurance included ionization chamber measurements and a novel 12C(n,2n)11C positron emission portal imaging system. kV portal imaging was used to confirm patient setup prior to each treatment session. All patients were prescribed 18.4 Gy at 1.15 Gy/fraction, delivered 4 days/week, which is equivalent to an x-ray EQD2 of approximately 70 Gy (RBE ∼ 3.8). Clinical observations suggest the RBE for radioresistant HNC may be as large as 8. Patients underwent weekly toxicity assessment, and acute toxicities were graded (G) by CTCAE v5.0.

RESULTS

Ten patients received IMNT, median age 61 (range 34-78). Primary tumor sites were base of tongue (n = 3), sinonasal (n = 3), parotid (n = 2), submandibular (n = 1), larynx (n = 1). Tumor histologies included adenoid cystic carcinoma (n = 7), other salivary gland carcinomas (n = 2) and mucosal melanoma (n = 1). Most had T4 disease (n = 8) and one had N3b disease. Six had surgical resection with high-risk features, and 6 had gross measurable disease prior to IMNT. None had concurrent systemic therapy. Uninvolved salivary glands were spared in most patients. All patients completed treatment. Median follow up was 22 days (0-48). Acute toxicities (n, G 1, 2, 3) included skin (8, 3, 0), dysgeusia (1, 6, 0), xerostomia (3, 5, 0), mucositis (2, 0, 5), nausea (3, 0, 1). One patient had >10% weight loss and brief admission for supportive care and PEG placement; one patient had prophylactic PEG; both regained oral independence during follow-up. There was no Grade 4+ toxicity.

CONCLUSION

IMNT improves the therapeutic ratio compared to 3D conformal NT and expands indications for NT in patients with radiorefractory tumors. Acute toxicity compares favorably with photons. Longer clinical and toxicity follow-up is anticipated. A prospective trial is planned to evaluate quality of life measures.

Quality of life after laryngectomy: are functional disabilities important?

BACKGROUND

The purpose of this study was to determine the functional disabilities and overall quality of life (QOL) of patients successfully treated (ie, without evidence of disease at two years) for laryngeal or hypopharyngeal cancer by a total laryngectomy.

METHODS

The University of Washington QOL questionnaire was administered to 10 patients prior to laryngectomy, at one year postlaryngectomy, and at two years postlaryngectomy.

RESULTS

Postlaryngectomy QOL scores were not significantly different from prelaryngectomy scores. In all QOL domains the severity of functional disability was not significantly correlated with its importance. Ninety percent of patients (9/10) reported that compared with one year prior to the diagnosis of cancer their general health was the same or better at two years postlaryngectomy. Seventy percent of patients (7/10) reported having a good to excellent overall QOL.

CONCLUSIONS

Though the loss of voice is disabling, the functional limitations caused by a laryngectomy do not necessarily translate into a worse overall QOL. Future research is needed to determine whether the importance of individual QOL domains changes as patients adjust to the experience of having and surviving cancer.

Cyclin D1 expression as a prognostic parameter in papillary carcinoma of the thyroid

Papillary carcinoma of the thyroid is the most common thyroid cancer. At the time of clinical presentation, most papillary carcinomas are still confined to the thyroid gland, and appropriate surgical treatment achieves a 95% 5-year survival rate. Certain carcinomas, however, behave in a much more aggressive fashion. Because specific therapies do not exist, for those tumors that have escaped local control, patients with disseminated disease have little or no chance of permanent cure or long-term survival. Cyclin D1, a protein that plays a critical role in the control of the cell cycle, has been shown to be overexpressed in a variety of human neoplasias and may serve as a prognostic parameter of disease progression. To explore the role played by cyclin D1 in the pathogenesis of thyroid papillary carcinoma, we have quantitated, by computerized image analysis, the immunohistochemical expression of cyclin D1 in formalin-fixed, paraffin-embedded tissue from 35 conventional papillary carcinomas of the thyroid and correlated the results with established clinicopathologic parameters and available survival data.

Destructive tophaceous calcium hydroxyapatite tumor of the infratemporal fossa. Case report and review of the literature

Tophaceous pseudogout is one of the rarest forms of crystal deposition disease, typically presenting as a destructive and invasive mass involving the temporomandibular joint or the infratemporal fossa region in the absence of any other articular manifestations. Previous cases have been assumed to be caused by calcium pyrophosphate dihydrate (CPPD) crystal deposition, based on finding weakly birefringent crystals in the involved tissues. The authors present the unique case of a 65-year-old woman with a destructive and invasive facial mass extending to the middle cranial fossa with microscopic and clinical features consistent with tophaceous pseudogout. High-resolution x-ray crystallographic powder diffraction and Fourier transformed infrared spectroscopy subsequently revealed that the crystals were composed of calcium hydroxyapatite without CPPD. The patient was later found to have primary hyperparathyroidism and mild hypercalcemia. This case demonstrates that tissue deposits of calcium hydroxyapatite can cause a destructive and invasive mass containing weakly birefringent crystals and raises the question of whether previous cases attributed to tophaceous pseudogout resulting from CPPD actually were composed of birefringent calcium hydroxyapatite.

A modified design of the buried radial forearm free flap for use in oral cavity and pharyngeal reconstruction

OBJECTIVE

We present a new design for the radial forearm flap that includes a small monitor segment that is connected to the primary skin paddle by a fascial subcutaneous segment of tissue. This design modification permits buried flaps to be easily monitored and provides vascularized tissue coverage of the flap vessels as well as the great vessels in the neck. Immediate augmentation of the radical neck deformity can be achieved.

SETTING

This study was conducted at a referral center.

PATIENTS

Fifteen patients with squamous cell cancer of the pharynx and tongue base were included in this study. The defects in these patients were judged to be best reconstructed with a radial forearm free flap.

RESULTS

All free flaps in this series survived. There was one case, described in detail, in which the fascial subcutaneous portion of the flap was exposed to salivary contamination. The flap vessels remained well protected and flap viability was unimpaired.

Free Tissue Transfer for Skull Base Reconstruction Analysis of Complications and a Classification Scheme for Defining Skull Base Defects

OBJECTIVE

The role of free flaps in skull base reconstruction is discussed in detail. Twenty-six microvascular free tissue transfers performed in 22 patients are reviewed in detail. A classification scheme for skull base defects is presented.

SETTING

Tertiary referral center.

PATIENTS

Twenty-two patients with neoplasms that involve the skull base underwent a combined craniotomy and facial approach for resection. The resultant defects were reconstructed with a variety of microvascular free flaps.

RESULTS

All 22 patients were ultimately successfully reconstructed with a free flap. One patient required a second free flap following ablative surgery for a recurrent tumor. The initial free flaps in three patients were unsuccessful and a second flap was required. The classification scheme was applied to all defects.

CONCLUSIONS

The creation of a functional separation of the intracranial and extracranial cavities can be extremely difficult to accomplish, especially when multiple cavities (nasal, oral, pharyngeal) are violated. Free flaps provide a solution to this problem in select cases. Skull base defects can and should be classified for the purpose of communication, treatment planning, prognosis of reconstruction, and judging therapeutic outcome.