A retrospective multicenter study of carbon-ion radiotherapy for external auditory canal and middle ear carcinomas

Survival Outcomes in Squamous Cell Carcinoma of the External Auditory Canal: A Systematic Review and Meta-Analysis

Squamous cell carcinomas (SCC) of the external auditory canal (EAC) are rare tumors representing a surgical challenge. Current knowledge is based largely on case series; thus, the level of evidence is weak. This study sought to systematically review the available SCC of the EAC literature and to identify risk factors for overall survival (OS) and disease-specific survival (DSS). A systematic review and meta-analysis of papers searched up to December 2022 through PubMed, Scopus, Web of Science, and Cochrane Library databases was conducted. Quality assessment of the eligible studies was done according to the Newcastle-Ottawa Scale. Pooled univariate and multivariable analyses and meta-analysis using a random-effects or fixed-effects Mantel-Haenszel model were performed. Fifteen articles (282 patients) met the inclusion criteria and were included in the quantitative analysis. The pooled multivariable analysis revealed cT3 and cT4 as independent prognostic factors for OS (p = 0.005, and p < 0.001, respectively) and DSS (p = 0.002, and p < 0.001, respectively). Local recurrence rate was 32.3%. The meta-analysis estimated significantly higher odds ratios for advanced T categories, than cT1-T2 tumors for OS and DSS (OR = 3.55; 95% CI, 1.93–6.52, and OR = 3.73; 95% CI, 2.00–6.97, respectively). In conclusion, locally advanced tumors were associated with poor prognosis. Poor outcomes mostly occurred due to local recurrence.

Salivary gland cancers in elderly patients: challenges and therapeutic strategies

Salivary gland carcinomas (SGCs) are the most heterogeneous subgroup of head and neck malignant tumors, accounting for more than 20 subtypes. The median age of SGC diagnosis is expected to rise in the following decades, leading to crucial clinical challenges in geriatric oncology. Elderly patients, in comparison with patients aged below 65 years, are generally considered less amenable to receiving state-of-the-art curative treatments for localized disease, such as surgery and radiation/particle therapy. In the advanced setting, chemotherapy regimens are often dampened by the consideration of cardiovascular and renal comorbidities. Nevertheless, the elderly population encompasses a broad spectrum of functionalities. In the last decades, some screening tools (e.g. the G8 questionnaire) have been developed to identify those subjects who should receive a multidimensional geriatric assessment, to answer the question about the feasibility of complex treatments. In the present article, we discuss the most frequent SGC histologies diagnosed in the elderly population and the relative 5-years survival outcomes based on the most recent data from the Surveillance, Epidemiology, and End Results (SEER) Program. Moreover, we review the therapeutic strategies currently available for locoregionally advanced and metastatic disease, taking into account the recent advances in precision oncology. The synergy between the Multidisciplinary Tumor Board and the Geriatrician aims to shape the most appropriate treatment pathway for each elderly patient, focusing on global functionality instead of the sole chronological age.

A cross-sectional analysis of registered clinical trials on the use of particle beam radiation therapy in head and neck cancers

Background

To present and analyze the current status of registered clinical trials on particle beam (including proton and carbon ion beam) radiation therapy (PBRT) for head and neck (H&N) malignancies, and to provide insights for future clinical research, we designed the cross-sectional analysis.

Methods

We identified and analyzed all clinical trials of interest registered on ClinicalTrials.gov and PTCOG.ch until March 22, 2020.

Results

We identified 57 registered clinical trials related to the use of proton therapy or carbon ion radiation therapy (CIRT) in H&N malignancies. There were 20, 27, and 5 trials focused on CIRT, proton therapy, and both ions, respectively. The eligible trials were registered between 2007 and 2020, mainly focused on adenoid cystic carcinoma (ACC), squamous cell carcinoma (SCC), sinonasal malignancies (SNM), skull base tumors, locally advanced, and recurrent tumors. The nature of 23 (40%) trials were not stated and could not be identified. A total of 25 (44%) registered trials were phase II, including randomized controlled trials (RCTs). There were 14 RCTs (7 phase II, 2 phase II/III, 2 phase III, 1 phase I/II, and 2 phase not applicable), and 25 studies including RCTs were registered before the first enrolment. There were 11 completed clinical trials among the eligible trials, including 7 with published trial-related results.

Conclusions

Less than 10% of the countries with PBRT treatment facilities in operation have initiated clinical trials on H&N cancer. Furthermore, among all registered trials, less than 10% have been completed with results published. More clinical trials, especially high quality trials, are needed for optimizing and standardizing treatment techniques of PBRT for H&N malignancies.

Who Will Benefit from Charged-Particle Therapy?

Charged-particle therapy (CPT) such as proton beam therapy (PBT) and carbon-ion radiotherapy (CIRT) exhibit substantial physical and biological advantages compared to conventional photon radiotherapy. As it can reduce the amount of radiation irradiated in the normal organ, CPT has been mainly applied to pediatric cancer and radioresistent tumors in the eloquent area. Although there is a possibility of greater benefits, high set-up cost and dearth of high level of clinical evidence hinder wide applications of CPT. This review aims to present recent clinical results of PBT and CIRT in selected diseases focusing on possible indications of CPT. We also discussed how clinical studies are conducted to increase the number of patients who can benefit from CPT despite its high cost.

The Role of Particle Therapy in Adenoid Cystic Carcinoma and Mucosal Melanoma of the Head and Neck

Particle irradiation is suitable for resistant histologies owing to a combination of improved dose delivery with potential radiobiologic advantages in high linear energy transfer radiation. Within the head and neck, adenoid cystic carcinoma and mucosal melanoma are two such histologies, being radioresistant and lying closely proximal to critical structures. Here, we review the use of particle irradiation for adenoid cystic carcinoma and mucosal melanoma of the head and neck.

A retrospective analysis of radiotherapy in the treatment of external auditory canal carcinoma

External auditory canal carcinoma (EACC) is a rare disease. The current study aimed to evaluate the clinical outcomes of patients treated with external beam radiotherapy (EBRT) for EACC. The present study retrospectively reviewed 34 consecutive patients treated for EACC with EBRT between February 2001 and January 2019 at the University of Tokyo Hospital. Clinical staging was performed according to the modified Pittsburgh classification. Of all the included patients, seven patients were in the early stages (I or II) and 27 in the advanced stages (III or IV) of EACC. A total of 16 patients underwent EBRT and surgery (S+RT) pre- and/or postoperatively, while 18 patients underwent definitive radiotherapy (dRT). The median prescribed doses for the S+RT and dRT groups were 66 and 70 Gy, respectively. The median follow-up period for all patients was 22.4 months (range, 2-205 months). The 5-year overall survival rates of the S+RT and dRT groups were 66.7 and 45.1%, respectively. The progression-free survival rate at 5-year was 55.6% (95% confidence interval: 36.5-71.1%) for the entire cohort. A total of 14 patients experienced disease relapse after treatment, consisting of 11 locoregional recurrences and three distant metastases. The current study revealed the clinical outcomes of EBRT for EACC.

Primary Advanced Squamous Cell Carcinoma of the Temporal Bone: A Single-Center Clinical Study

OBJECTIVES/HYPOTHESIS

The extreme rarity of temporal bone squamous cell carcinoma (TB-SCC) has delayed the accumulation of high-quality clinical evidence. For the purposes of retrospective meta-analysis in the future, a large dataset with information from various institutions would be ideal. Our objective here was to retrospectively review cases of TB-SCC encountered at a single tertiary referral center and explore survival outcomes and prognostic factors.

STUDY DESIGN

Retrospective chart review.

METHODS

The medical records of all TB-SCC cases were retrospectively reviewed. The resulting dataset contained 71 cases of primary cancer eligible for initial definitive (curative) treatment.

RESULTS

T4 status was associated with lower disease-specific 5-year survival than T1 to T3 staging (T1: 100%, T2: 92%, T3: 86%, T4: 51%). Survival was significantly higher in operable than in inoperable cases, even when restricted to advanced (T3/T4) cancers. The tumor extension to the middle ear cavity was observed in 13/17 of T3 cases, but it was not associated with poor survival. In addition, among operable cases, negative surgical margins were associated with significantly higher survival than positive margins.

CONCLUSIONS

Definitive treatments can offer disease-specific 5-year survival of over 85% in T1 to T3 cases of TB-SCC. The tumor extension to the middle ear cavity is not associated with poor survival. T4 status, inoperability, nodal invasion, and positive surgical margin are identified as a predictor of poor prognosis. Still, the matter of how to deal with unresectable tumors remains an outstanding issue in the treatment of TB-SCC.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:E583-E589, 2021.

Carbon Ion Therapy: A Modern Review of an Emerging Technology

Radiation therapy is one of the most widely used therapies for malignancies. The therapeutic use of heavy ions, such as carbon, has gained significant interest due to advantageous physical and radiobiologic properties compared to photon based therapy. By taking advantage of these unique properties, carbon ion radiotherapy may allow dose escalation to tumors while reducing radiation dose to adjacent normal tissues. There are currently 13 centers treating with carbon ion radiotherapy, with many of these centers publishing promising safety and efficacy data from the first cohorts of patients treated. To date, carbon ion radiotherapy has been studied for almost every type of malignancy, including intracranial malignancies, head and neck malignancies, primary and metastatic lung cancers, tumors of the gastrointestinal tract, prostate and genitourinary cancers, sarcomas, cutaneous malignancies, breast cancer, gynecologic malignancies, and pediatric cancers. Additionally, carbon ion radiotherapy has been studied extensively in the setting of recurrent disease. We aim to provide a comprehensive review of the studies of each of these disease sites, with a focus on the current trials using carbon ion radiotherapy.

Radiobiological Characterization of Canine Malignant Melanoma Cell Lines with Different Types of Ionizing Radiation and Efficacy Evaluation with Cytotoxic Agents

Canine malignant melanoma (CMM) is a locally and systemically aggressive cancer that shares many biological and clinical characteristics with human mucosal melanoma. Hypofractionated radiation protocols have been used to treat CMM but little is known about its radiation biology. This pilot study is designed to investigate response of CMM cell lines to various ionizing radiations and cytotoxic agents to better understand this canine cancer. Four CMM cell lines were evaluated by clonogenic survival assay under aerobic and hypoxic conditions and parameters such as alpha beta (α/β) ratio, oxygen enhancement ratio (OER), and relative biological effectiveness (RBE) were calculated after ¹³⁷Cs, 6 megavoltage (MV) photon, or carbon ion irradiation. Six cytotoxic agents (cisplatin, camptothecin, mitomycin C, bleomycin, methtyl methanesulfonate and etoposide) were also assessed for their efficacy. Under aerobic condition with 6 MV photon, the α/β ratio of the four cell lines ranged from 0.3 to >100, indicating a wide variation of cellular sensitivity. The ratio increased under hypoxic condition compared to aerobic condition and this was more dramatic in ¹³⁷Cs and 6 MV photon treatments. OER of carbon was lower than ¹³⁷Cs at D₁₀ in 3 of the 4 cell lines. The RBE values generally increased with the increase of LET. Different cell lines showed sensitivity/resistance to different cytotoxic agents. This study revealed that CMM has a wide range of radiosensitivity and that hypoxia can reduce it, indicating that widely used hypofractionated protocols may not be optimal for all CMM patients. Several cytotoxic agents that have never been clinically assessed can improve treatment outcome.

A retrospective multicenter study of carbon-ion radiotherapy for external auditory canal and middle ear carcinomas

Background

We conducted a retrospective multicenter study to assess the clinical outcomes of carbon‐ion radiotherapy (CIRT) for head and neck malignancies (Japan Carbon‐Ion Radiation Oncology Study Group [J‐CROS] study: 1402 HN). We aimed to evaluate the safety and efficacy of CIRT in patients with external auditory canal (EAC) and middle ear (ME) carcinomas.

Methods

Thirty‐one patients treated with CIRT at four Japanese institutions were analyzed. Fourteen patients (45.2%) had squamous cell carcinomas, 13 (41.9%) had adenoid cystic carcinomas, and four (12.9%) had other types. Nineteen (61.3%), six (19.4%), three (9.7%), and three (9.7%) patients had T4, T3, T2, and T1 disease, respectively. All patients had N0M0 status. The median radiation dose was 64 Gy (relative biological effectiveness) in 16 fractions. The median gross tumor volume was 33.3 mL.

Results

The median follow‐up period was 18.4 months (range, 5.1‐85.6). The 1‐ and 3‐year local control and overall survival rates were 75.0% and 55.0% and 79.3% and 58.7%, respectively. Regarding grade 3 or higher toxicities, three patients (9.7%) had grade 3 dermatitis, one (3.2%) had grade 3 mucositis, and two (6.5%) had grade 3 central nervous necrosis (ie, radiation‐induced brain necrosis). No grade 4 or worse reactions were observed.

Conclusion

CIRT was effective for EAC and ME carcinomas.