Neutron vs photon irradiation of inoperable salivary gland tumors: results of an RTOG-MRC Cooperative Randomized Study

Effects of tissue heterogeneity and comparisons of collapsed cone and Monte Carlo fast neutron patient dosimetry using the University of Washington clinical neutron therapy system (CNTS)

Fast neutron therapy is a high linear energy transfer (LET) radiation treatment modality offering advantages over low LET radiations. Multileaf collimator technology reduces normal-tissue dose (toxicity) and makes neutron therapy more comparable to MV x-ray treatments. Published clinical-trial and other experiences with fast neutron therapy are reported. Early comparative studies failed to consider differences in target-dose spatial conformality between x-ray and neutron treatments, which is especially important for organs-at-risk close to tumor targets. Treatments planning systems (TPS) for high-energy neutrons lag behind TPS tools for MV x-rays, creating challenges for comparative studies of clinical outcomes. A previously published Monte Carlo model of the University of Washington (UW) Clinical Neutron Therapy System (CNTS) is refined and integrated with the RayStation TPS as an external dose planning/verification tool. The collapsed cone (CC) dose calculations in the TPS are based on measured dose profiles and output factors in water, with the absolute dose determined using a tissue-equivalent ionization chamber. For comparison, independent (external) Monte Carlo simulation computes dose on a voxel-by-voxel basis using an atlas that maps Hounsfield Unit (HU) numbers to elemental composition and density. Although the CC algorithm in the TPS accurately computes neutron dose to water compared to Monte Carlo calculations, calculated dose to water differs from bone or tissue depending largely on hydrogen content. Therefore, the elemental composition of tissue and bone, rather than the material or electron density, affects fast neutron dose. While the CC algorithm suffices for reproducible patient dosimetry in fast neutron therapy, adopting methods that consider tissue heterogeneity would enhance patient-specific neutron dose accuracy relative to national standards for other types of ionizing radiation. Corrections for tissue composition have a significant impact on absolute dose and the relative biological effectiveness (RBE) of neutron treatments compared to other radiation types (MV x-rays, protons, and carbon ions).

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.

Salivary Gland Cancers

Salivary gland carcinomas are a rare and heterogenous group of cancers with varying underlying biology and clinical behavior. A quickly evolving body of data has advanced the understanding of these tumors, leading to effective therapeutics for several histologic subtypes. Biologically rational clinical trials have developed from an understanding of MYB and NOTCH signaling in adenoid cystic carcinoma. The recognition of androgen receptor signaling and HER2-targeted therapy has offered therapeutic options in non-ACC salivary cancers. The use of TRK inhibitors in salivary secretory carcinoma has led to exceptional responses. Immunotherapy is an exciting new therapeutic avenue that requires further exploration.

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 Combined Neutron and Proton Regimen for Advanced Salivary Tumors: Early Clinical Experience

Background and objective  Fast neutron radiotherapy (NRT) is a high linear energy transfer (LET) particle therapy that offers a local control (LC) advantage over low-LET X-rays in the treatment of advanced and unresectable salivary gland malignancies. However, in tumors approximating the base of skull (BOS), target volumes may be underdosed to minimize toxicity to the central nervous system (CNS). In this setting, a proton beam boost to the underdosed part of the tumor may improve LC. We report our early experience with a hybrid neutron-proton approach in patients with BOS involvement. Materials and methods We retrospectively reviewed 29 patients with locally advanced and unresectable salivary gland tumors involving the BOS between 2014-2018. The median age of the patients was 56 years, with the majority of them having adenoid cystic carcinomas (ACC) (79%) with advanced T4a/b disease (86%), pathologic perineural invasion (PNI) (55.2%), and orbital invasion (34.5%). Five patients (17.2%) were cases of re-irradiation. Surgical resection was attempted in 15 patients (51.7%), of which none achieved negative margins. The median neutron dose was 18.4 neutron Gray (nGy) with a sequential proton boost (PB) with a median dose of 25 Gy [relative biological effectiveness (RBE)] (range: 16-45 Gy). Toxicity was graded per the Common Terminology Criteria for Adverse Events (CTCAE) version 4.03. Descriptive statistics and the Kaplan-Meier method were used. Results At a median follow-up of 18.9 months [interquartile range (IQR): 6.1-32.5], the entire cohort's overall survival (OS) was 93.1%, progression-free survival (PFS) was 79.3%, and LC was 89.7%. Among patients who were not re-irradiated (n=24), the most commonly recorded acute grade 3 toxicities were mucositis (50%) and dermatitis (37.5%). There was no documented acute grade 4/5 events. Late grade 3/4 events included trismus (n=1), hearing loss (n=2), visual loss (n=6), and bone necrosis (n=1). There were no reported late grade 5 events in de novo patients. Conclusion In this challenging cohort with a poor prognosis, early outcomes for a hybrid neutron-proton approach were found to be promising. Further studies involving longer follow-ups with a larger cohort of patients are required to validate our findings.

Treatment outcomes of elderly salivary gland cancer patients undergoing radiotherapy - Results from a large multicenter analysis

BACKGROUND AND PURPOSE

To evaluate oncological outcomes and treatment-related toxicities of elderly salivary gland cancer patients undergoing (chemo)radiotherapy.

MATERIAL AND METHODS

Local/locoregional control (LRC), progression-free survival (PFS) and overall survival (OS) of elderly patients ≥ 65 years with primary salivary gland cancers undergoing (chemo)radiotherapy between 2005 and 2020 at three tertiary cancer centers were calculated. The impact of clinicopathological and treatment parameters on outcomes were analyzed, and acute and chronic toxicities were quantified.

RESULTS

288 elderly salivary gland cancer patients were included in this multicenter analysis, and their median LRC, PFS and OS amounted to 113, 39 and 75 months, respectively. Age, performance status, comorbidities, definitive vs. adjuvant (chemo)radiotherapy as well as locally/locoregionally advanced cancers and distant metastases correlated with reduced outcomes in elderly salivary gland patients. Patients receiving dose-escalated radiotherapy (total doses > 70 Gy_EQD2) with carbon ion boost radiation resulted in improved LRC, but no improvements in PFS or OS. Concomitant chemoradiotherapy did not improve treatment outcomes in elderly salivary gland carcinoma patients. Radiotherapy of elderly salivary gland cancer patients resulted in moderate higher-grade toxicities despite dose escalation with 70 (24.3%) and 48 patients (16.7%) experiencing acute and chronic grade 3 toxicities, respectively. No grade 4/5 toxicities were observed in this patient cohort.

CONCLUSION

Data from the largest multicenter analysis of elderly salivary gland cancer patients undergoing (chemo)radiotherapy demonstrate favorable LRC and tolerable toxicity rates. Decision-making for these vulnerable patients should be based on patient performance rather than chronological patient age.

Radiation-induced toxicities and outcomes after radiotherapy are independent of patient age in elderly salivary gland cancer patients: results from a matched-pair analysis of a rare disease

Purpose

This study analyzed survival and toxicity after (chemo)radiotherapy for primary salivary gland cancer patients aged ≥ 65 years and compared these results with younger patients using a matched-pair analysis.

Methods

Twenty-nine elderly patients with primary salivary gland carcinomas treated with (chemo)radiotherapy from 2008 to 2020 at University of Freiburg Medical Center were analyzed for oncological outcomes and therapy-associated toxicities. Local/locoregional control (LRC), progression-free survival (PFS) and overall survival (OS) were calculated using the Kaplan–Meier method, and the influence of clinical parameters on patient outcomes was assessed. A matched-pair analysis was performed after matching with patients < 65 years.

Results

Nine patients (31.0%) received definitive (chemo)radiotherapy, and 20 patients (69.0%) were treated in the adjuvant setting. 2-year LRC, PFS and OS ranged at 82.4%, 53.7% and 71.8%, respectively. Smoking (HR 3.980, p = 0.020), reduced performance status (HR 3.735, p = 0.016) and higher comorbidity burden (HR 4.601, p = 0.005) correlated with inferior OS. Using a matched-pair analysis with younger patients, elderly patients exhibited a trend towards reduced OS (HR 3.015, p = 0.065), but not PFS (HR 1.474, p = 0.371) or LRC (HR 1.324, p = 0.633). Acute and chronic grade 3 toxicities occurred in 31.0% and 12.5% of elderly patients, respectively, and the matched-pair analysis revealed no significant differences between age groups regarding treatment-related toxicities.

Conclusion

Treatment-related toxicities as well as LRC and PFS were comparable for salivary gland cancer patients undergoing radiotherapy. Therefore, concerns for more pronounced toxicities or reduced local/locoregional response rates should not guide treatment decisions in affected elderly patients.

Electronic supplementary material

The online version of this article (10.1007/s00405-020-06393-x) contains supplementary material, which is available to authorized users.

Neutron Therapy for High-Grade Salivary Carcinomas in the Adjuvant and Primary Treatment Setting

OBJECTIVES/HYPOTHESIS

Our primary objective was to compare differences in survival of patients with high-grade salivary gland carcinomas (SGCs) receiving adjuvant neutron versus photon radiotherapy using a hospital-based national cohort and restricted mean survival time (RMST) analysis. Our secondary objective was to compare survival of similar patients treated with primary neutron versus photon radiation.

STUDY DESIGN

Multicenter, retrospective population-based study of patients within the National Cancer Database from 2004 to 2014.

METHODS

One thousand eight hundred forty-four patients were selected on diagnosis of high-grade parotid and submandibular malignancies. One thousand seven hundred seventy-seven patients receiving photon and 67 patients receiving neutron therapy were identified who met inclusion criteria. Patients were then categorized as having primary surgery with adjuvant radiation or primary radiation without prior surgery. Bivariate analysis was performed to assess for differences between groups, and RMST analysis was performed at 1-, 2-, and 5-year timepoints with controlling for available covariate data.

RESULTS

There was no significant difference in RMST for patients receiving neutrons over photons at 1, 2, and 5 years in the adjuvant setting. Among patients undergoing primary radiotherapy, there was a difference in RMST of 2.29 months at 1 year and 5.05 months at 2 years for neutrons over photons, though this benefit was not observed at 5 years post-therapy.

CONCLUSIONS

For patients with high grade SGCs undergoing adjuvant photon versus neutron radiotherapy, there was no difference in RMST. There was observed to be a significant difference in RMST at 1 and 2 years among patients undergoing primary neutron therapy of up to 5 months. Given the benefit observed with primary neutron therapy, it should be considered in both the primary and adjuvant treatment setting.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:541-547, 2021.

Cancers of the Major Salivary Gland

Salivary gland malignancies are rare tumors that comprise multiple histologic entities with diverse clinical behavior. Mucoepidermoid carcinoma is the most frequent primary salivary malignancy, followed by adenoid cystic and acinic cell carcinoma. Although most salivary malignancies are asymptomatic, presentation with a rapidly enlarging mass may be accompanied by pain, functional neurologic deficits, soft-tissue invasion, or nodal enlargement. Assessment of clinical behavior and physical exam greatly contributes to diagnostic workup. Preoperative imaging, to include ultrasound, computed tomography, or magnetic resonance imaging, may assist with surgical planning. Limitations of preoperative fine-needle aspiration cytology mean that, in some cases, definitive histologic diagnosis may not be established until therapeutic surgery is undertaken. Treatment strategies rely on oncologic resection of the primary site with negative margins as well as adjuvant radiotherapy in patients with high-risk features, such as high-grade histology, advanced T class, or perineural invasion. Regional lymphadenectomy is recommended for involved nodal basins. Patients with clinically node-negative disease at high risk for occult nodal metastases may be considered for elective lymphadenectomy or radiotherapy. Use of chemotherapy in the adjuvant setting, in combination with radiotherapy, remains controversial. The rate of objective response to palliative chemotherapy in recurrent or metastatic salivary gland malignancy remains low. In studies that include a significant proportion of adenoid cystic carcinomas, whether disease stability represents an indolent disease process or the true effect of a therapeutic drug may be difficult to discern. Recognition of genetic alterations and protein expression unique to salivary malignancies presents exciting new opportunities for molecularly targeted therapy, although the response to molecularly targeted therapy in studies has been modest thus far.

Definitive Carbon-Ion Radiation Therapy for Locally Advanced Sinonasal Malignant Tumors: Subgroup Analysis of a Multicenter Study by the Japan Carbon-Ion Radiation Oncology Study Group (J-CROS)

PURPOSE

To evaluate the safety and efficacy of carbon-ion radiation therapy (C-ion RT) for locally advanced sinonasal malignant tumors in a multicenter retrospective study (J-CROS 1402 HN).

METHODS AND MATERIALS

Clinical data were collected for patients who had sinonasal malignant tumors of stage N0-1M0 and received C-ion RT at 4 institutions in Japan between November 2003 and December 2014. Of the 458 patients, 393 had naïve tumors and 65 had recurrent tumors. The tumors were located in the nasal cavity (n = 263), maxillary sinus (n = 109), ethmoid sinus (n = 71), and other locations (n = 15). The histologic types were mucosal melanoma (n = 221, 48%), adenoid cystic carcinoma (n = 122, 27%), squamous cell carcinoma (n = 31, 7%), olfactory neuroblastoma (n = 30, 7%), adenocarcinoma (n = 21, 5%), and other types (n = 33, 7%). Of the 458 patients, 300 (66%) had T4 tumors. All patients received definitive C-ion RT.

RESULTS

The median follow-up period was 25.2 months for all patients (range, 1.4-132.3 months). The 2-year overall survival and local control rates were 79.6% and 84.1%, respectively. As analyzed according to histology, the 2-year overall survival rate was 68.0% for mucosal melanoma, 96.8% for adenoid cystic carcinoma, 70.0% for squamous cell carcinoma, 96.7% for olfactory neuroblastoma, and 89.7% for adenocarcinoma. Regarding late toxicities, 17% of patients developed grade 3 and 4 toxicities, of which visual impairment was the most common.

CONCLUSION

The results of our multicenter study have demonstrated that C-ion RT can provide excellent clinical outcomes with acceptable late toxicities in patients who have locally advanced sinonasal malignant tumors.

Orbital Apex Metastasis from Adenoid Cystic Carcinoma: Acute Loss of Vision and Subsequent Recovery with the Radiation

Orbital apex metastasis from adenoid cystic carcinoma (ACC) is rare. We present a patient with known metastatic ACC presented with a rapidly declining vision with visual acuity oculus dexter (OD) equal to counting fingers at two feet. On imaging, she was found to have a right orbital apex tumor causing compressive optic neuropathy. She received the intensity modulated radiation therapy (IMRT). After completion of the therapy, she had regained essentially a full vision with visual acuity OD of 20/30 without corrective lenses. The treatment rationale and pertinent literature are discussed in this article.

Carbon ion therapy (C12) for high-grade malignant salivary gland tumors (MSGTs) of the head and neck: do non-ACCs profit from dose escalation?

Purpose

To evaluate the use of high-dose radiotherapy using carbon ions (C12) on non-adenoid cystic malignant salivary gland tumors (MSGT).

Patients and methods

Between 2009 and 2013, patients with biopsy-proven non-ACC MSGT histologies of the head and neck received a combined regimen of IMRT plus C12 boost. Treatment toxicity (CTC v3), response (RECIST 1.1), control and survival rates were retrospectively analyzed.

Results

40 patients with pathologically confirmed non-ACC MSGT (T4: 45 %; N+: 40 %; gross residual: 58 %; mucoepidermoid carcinoma (MEC): 45 %; adenocarcinoma: 20 %) were treated with a median of 74 GyE (80 Gy BED). Chemoradiation was given in 5 patients with MEC. Grade III acute toxicity was observed in up to 15 % (mucositis, dermatitis, dysphagia), no higher-grade late toxicity occurred to date. At a follow-up of 25.5 months, LC, and PFS at 2 and 3 years are 81.5 % (LC) and 66.8 % (PFS), OS at 2 and 3 years is 83.6 % and 72.8 %. Most frequent site of disease progression was distant metastasis. Histologic subtype correlated with LC and PFS. Resection status (gross vs microscopic disease) had no significant effect on LC, PFS, or OS.

Conclusion

The treatment is well tolerated, no higher grade late effects were observed. Considering the negative pre-selection, LC, PFS and OS are promising. While histology and site of origin significantly influenced control and survival rates, resection status did not, potentially due to the effect of dose escalation.

Electronic supplementary material

The online version of this article (doi:10.1186/s13014-016-0657-z) contains supplementary material, which is available to authorized users.

Salivary Gland. Photon beam and particle radiotherapy: Present and future

Salivary gland cancers (SGCs) are rare diseases and their treatment depends upon histology, stage and site of origin. Radical surgery is the mainstay of treatment but radiotherapy (RT) plays a key role in both the postoperative and the inoperable setting, as well as in recurrent disease. In the absence of prospective randomized trials, a wide retrospective literature suggests postoperative RT (PORT) in patients with high risk pathological features. SGCs, and adenoid cystic carcinoma (ACC) in particular, are known to be radio-resistant tumors and should therefore respond well to particle beam therapy. Recently, excellent outcome has been reported with radical carbon ion RT (CIRT) in particular for ACC. Both modern photon- and hadron-based treatments are effective and are characterized by a favourable toxicity profile. But it is not clear whether one modality is superior to the other for disease control, due to the differences in patients' selection, techniques, fractionation schedules and outcome measurements among clinical experiences. In this paper, we review the role of photon and particle RT for malignant SGCs, discussing the difference between modalities in terms of biological and technical characteristics. RT dose and target volumes for different histologies (ACC versus non-ACC) have also been taken into consideration.

Neutron radiation therapy for advanced thyroid cancers

PURPOSE

The aim of this study was to review institutional outcomes for advanced thyroid cancers treated with fast neutron radiation therapy (FNRT) and photon radiation therapy (RT).

METHODS AND MATERIALS

In all, 62 consecutive patients were analyzed. Fifty-nine had stage IV disease. Twenty-three were treated with FNRT and 39 with photon RT. Median follow-up was 14 months. The primary endpoint was overall survival (OS).

RESULTS

There was no significant difference in median OS between FNRT and photon RT (26 vs 16 months; P = .49). Patients with well-differentiated histologies had superior median OS with photon RT (17 vs 69 months; P = .04). There was a nonsignificant trend toward improved OS with FNRT for medullary and anaplastic histologies.

CONCLUSIONS

Outcomes in this study are in line with historical results. There is an apparent detriment in OS with FNRT for well-differentiated histologies and a trend toward improved OS with medullary and anaplastic histologies that warrants further investigation.

The efficacy of iodine-125 permanent brachytherapy versus intensity-modulated radiation for inoperable salivary gland malignancies: study protocol of a randomised controlled trial

Background

Radiation therapy is the method of choice for subjects with inoperable salivary gland malignancies. I-125 brachytherapy, delivering a high radiation dose to a tumor but sparing surrounding normal tissues, is supposed to be ideal modality for the treatment of salivary gland malignancies. We designed a randomised controlled clinical trial to compare the efficacy of I-125 permanent brachytherapy (PBT) versus intensity-modulated radiation therapy (IMRT) for inoperable salivary gland malignancies.

Methods/Design

In this study, inclusion criteria are subjects with inoperable salivary gland malignancies, aged 18–80 years, have provided informed consent, with at least one measurable tumor focus, be able to survive ≥3 months, Karnofsky performance status ≥60, have adequate hematopoietic function of bone marrow, have normal liver and kidney function, and are willing to prevent pregnancy.

Exclusion criteria include a history of radiation or chemotherapy, a history of other malignant tumors in the past 5 years, receiving other effective treatments, participating in other clinical trials, with circulatory metastasis, cognitive impairment, severe cardiovascular and cerebrovascular diseases, acute infection, uncontrolled systemic disease, history of interstitial lungdisease, and being pregnant or breast feeding.

The study will be conducted as a clinical, prospective, randomised controlled trial with balanced randomisation (1:1). The planned sample size is 90 subjects. Subjects with inoperable salivary gland malignancies are randomised to receive either I-125 PBT or IMRT, with stratification by tumor size and neck lymph node metastasis. Participants in both groups will be followed up at 2, 4, 6, 9, 12, 15, 18, 21 and 24 months after randomization. The primary outcome is local control rate of the primary site (based on imaging findings and clinical examination, RECIST criteria) in 1 year. Secondary outcomes are progression-free survival, overall survival, quality of life (QOL) measured with the European Organization for Research and Treatment of Cancer QOL Questionnaire (EORTC QLQ-C30 and QLQ-H&N35) of Chinese version, and safety of treatment. Chi-squared test is used to compare the local control rates in both groups. The survival curves are estimated by the Kaplan-Meier method, and log-rank test is used to test the significant difference.

Discussion

Only few observational studies have investigated the effect of I-125 PBT on inoperable salivary gland malignancies. To our knowledge, this is the first randomised controlled trial to investigate the efficacy of I-125 PBT for subjects with inoperable salivary gland malignancies, and will add to the knowledge base for the treatment of these subjects.

Trial registration

The study is registered to Clinical Trials.gov (NCT02048254) on Jan 29, 2014.

Cancers of major salivary glands

Major salivary gland malignancies are a rare but histologically diverse group of entities. Establishing the diagnosis of a malignant salivary neoplasm may be challenging because of the often minimally symptomatic nature of the disease, and limitations of imaging modalities and cytology. Treatment is centered on surgical therapy and adjuvant radiation in selected scenarios. Systemic therapy with chemotherapeutic agents and monoclonal antibodies lacks evidence in support of its routine use.

Definitive proton radiation therapy and concurrent cisplatin for unresectable head and neck adenoid cystic carcinoma: A series of 9 cases and a critical review of the literature

BACKGROUND

The primary treatment for head and neck adenoid cystic carcinoma (ACC) is surgery. Infrequently, however, ACC's propensity for perineural and base of skull invasion can preclude definitive surgical management. We present our experience with proton radiation therapy (RT) and concurrent platinum-based chemotherapy.

METHODS

Nine patients with unresectable node-negative, nonmetastatic head and neck ACC received definitive proton RT and concurrent cisplatin. Outcomes and toxicities were recorded. A systematic review of the literature was performed.

RESULTS

Median follow-up was 27 months (range, 9.2-48.3 months). Four patients achieved complete response at the primary site, and an additional 4 patients achieved stabilization of local disease. Only 1 patient developed local disease progression. Four patients had 5 acute grade 3 (G3) toxicities, and 1 patient developed a chronic G4 optic nerve disorder.

CONCLUSION

Our preliminary results suggest proton RT and concurrent chemotherapy is a definitive treatment option for select patients with head and neck ACC. © 2015 Wiley Periodicals, Inc. Head Neck 38: E1472-E1480, 2016.

A rationale for chemoradiation (vs radiotherapy) in salivary gland cancers? On behalf of the REFCOR (French rare head and neck cancer network)

BACKGROUND

Salivary gland carcinomas constitute a heterogeneous group of tumors, with over 20 histological subtypes of various prognoses. The mainstay of treatment is surgery, with radiotherapy advocated for unresectable disease or postoperatively in case of poor prognostic factors such as high grade, locally advanced and/or incompletely resected tumors. Concurrent chemotherapy is sometimes advocated in routine practice based on criteria extrapolated from squamous cell carcinomas of the head and neck, on radioresistance of salivary gland tumors and on results obtained in the metastatic setting. The aim of this review was to identify situations where chemotherapy is advocated.

MATERIAL AND METHODS

A search of literature was performed with the following key words: parotid, salivary gland, neoplasm, cancer, malignant tumor, chemoradiation, chemotherapy, radiotherapy and treatment. Case report and studies published before 2000 were not included.

RESULTS

Platinum-based regimens were the most frequent. Other regimens were reported and seemed dependent on histology. The level of evidence for the concurrent delivery of chemotherapy with radiation therapy is supported by a low level of evidence. Prescribing chemotherapy mostly relies on poor prognostic factors similar to those used to indicate high dose radiotherapy. Protocols vary with histology.

CONCLUSION

The rationale for adding chemotherapy to radiotherapy remains to be demonstrated prospectively. Although the type of systemic treatments used may be adapted on histology, the strongest rationale remains in favor of cisplatin.

Results of photon radiotherapy for unresectable salivary gland tumors: is neutron radiotherapy's local control superior?

Background

The results of RTOG-MRC randomized trial of photon (n=15) versus neutron (n=17) therapy in the 1980’s reported an improved local control (LC) with neutron radiotherapy for unresectable salivary gland tumors. Due to increased severe toxicity with neutron radiotherapy and the paucity of neutron-therapy centers, we analyzed our institution’s results of photon radiotherapy for unresectable salivary gland tumors.

Patients and methods

From 1990 to 2009, 27 patients with unresectable salivary gland cancer underwent definitive photon radiotherapy at our institution. Nodal involvement on presentation was found in 9 patients. Median dose of radiotherapy was 70 Gy. Chemotherapy was given to 18 patients, most being platinum-based regimens. Local control (LC), locoregional control (LRC), distant metastasis-free survival (DMFS), overall survival (OS), and toxicity outcomes were assessed.

Results

With a median follow-up of 52.4 months, the 2/5-year actuarial LC was 69% (95%CI ± 21.0%)/55% (± 24.2%), LRC was 65% (± 21.4%)/47% (± 21.6%), and DMFS was 71% (± 21.8%)/51% (± 22.8%), respectively using competing risk analysis. The median OS was 25.7 months, and the 2/5-year OS rates were 50% (± 19.0%)/29% (± 16.6%), respectively. Higher histologic grade was significant for an increased rate of DM (intermediate grade vs. low grade, p=0.04, HR 7.93; high grade vs. low grade, p=0.01, HR 13.50). Thirteen (48%) patient’s experienced acute grade 3 toxicity. Late grade 3 toxicity occurred in three (11%) patients.

Conclusions

Our data compares favorably to neutron radiotherapy with fewer late complications. Photon radiotherapy is an acceptable alternative to neutron radiotherapy in patients who present with unresectable salivary gland tumors.

Salivary gland carcinomas

INTRODUCTION

Salivary gland carcinomas are rare tumours of heterogeneous morphology that require distinctive surgical and adjuvant therapy.

METHODS

Relevant studies were electronically searched in PubMed and reviewed for innovative and important information.

RESULTS

Recent insights in genetic alterations like chromosomal aberrations, expression of receptor tyrosine kinases, malfunction of tumour suppressor genes or DNA promoter methylations increased the knowledge about aetiology and pathogenesis. New histological subtypes are recognised, and a three-tiered grading system seems reasonable. Ultrasound remains the basic diagnostic imaging procedure. New developments comprise the diffusion-weighed magnetic resonance imaging, while fluorodeoxyglucose positron emission tomography/computed tomography shows good diagnostic accuracy in detecting distant metastases and local recurrence. Fine-needle aspiration cytology helps in differentiating a neoplasia from a non-neoplastic lesion while being unreliable in recognising malignancy. In contrast, additional core needle biopsy and/or intraoperative frozen section diagnosis increase the accuracy in diagnosing a malignant lesion. Conservative parotid surgery with nerve monitoring remains state-of-the-art. Free flaps or musculoaponeurotic flaps are proposed for prevention of Frey's syndrome. As parotid cancer often shows skip metastases, complete ipsilateral neck dissection (level I-V) is indicated particularly in high-grade lesions. Adjuvant radio(chemo)therapy increases local tumour control, whereas overall survival is not necessarily improved. Current results of systemic chemotherapy or targeted therapy in advanced tumour stages are disappointing.

CONCLUSION

Despite several developments, salivary gland carcinomas remain a heterogeneous group of tumours challenging both pathologists and clinicians.

[Adenoid cystic carcinoma of the head and neck: a retrospective series of 169 cases]

PURPOSE

Adenoid cystic carcinoma represents 1% of head and neck cancers. Adenoid cystic carcinomas are slow growing tumours with high potential for local recurrence. Treatment usually associates radiotherapy and surgery, but the role of radiotherapy remains unclear. We report a retrospective multicentric study of the management and prognostic factors of 169 adenoid cystic carcinomas of head and neck.

PATIENTS AND METHODS

Between 1982 and 2010, 169 patients with adenoid cystic carcinoma of the head and neck were referred to the Cercle des oncologues radiothérapeutes du Sud departments of radiotherapy either for primary untreated tumour (n=135) or for a recurrence of previously treated tumour (n=34). The site of adenoid cystic carcinoma was: parotid gland (n=48, 28.4%), minor salivary gland (n=35, 20.7%), submandibular gland (n=22, 13%), sinus cavities (n=22, 13%), other (n=42, 24.9%). Tumour stages were: T1 (12.4%); T2 (14.2%); T3 (12.4%); T4 (41.4%) and Tx (19.5%). Lymph node involvement was 13% and distant metastasis 8.9%. For adenoid cystic carcinomas of the parotid gland, major nerve involvement was evaluated. Preferential site of metastasis was the lung (87.5%). Treatments were: surgery alone (n=27), surgery and adjuvant radiotherapy (n=89), surgery and adjuvant chemoradiotherapy (n=12), exclusive chemoradiotherapy (n=13), exclusive radiotherapy (n=14), other associations (n=5) and no treatment (n=7). Radiotherapy was delivered through photons (n=119), neutrons (n=6), both (n=4). Two patients had a brachytherapy boost. Median prescribed doses to T and N were respectively 65 Gy and 50 Gy for the 119 photons treated patients.

RESULTS

Mean follow-up was 58 months (range 1-250 months). As of December 1, 2010, 83 patients were alive with no evolutive disease (49%), 35 alive and had recurred, 18 had uncontrolled evolutive disease, 28 had died of adenoid cystic carcinoma and 5 of intercurrent disease. Overall survival and disease free survival were respectively 72% and 72% at 5 years, 53% and 32% at 10 years; 5 and 10-year freedom from local recurrence were 81% and 52% respectively. Nerve involvement was found in 17/48 parotid gland adenoid cystic carcinomas. The Cox model including all patients, showed that surgery (P<0.001), surgical margins (P=0.015), nerve involvement (P=0.0079), length of radiotherapy (P=0.018), and tumour location (P=0.041) were associated with disease free survival.

CONCLUSION

In this large series of adenoid cystic carcinoma of head and neck with a majority of T3-T4 tumours, 10-year survivals were achieved for 50% of patients. Radiotherapy did not impact survival.

IMRT and carbon ion boost for malignant salivary gland tumors: interim analysis of the COSMIC trial

Background

The COSMIC trial is designed to evaluate toxicity in dose-escalated treatment with intensity-modulated radiotherapy (IMRT) and carbon ion boost for malignant salivary gland tumors (MSGT) of the head and neck including patients with inoperable/ incompletely resected MSGTs (R2-group) and completely resected tumors plus involved margins or perineural spread (R1-group).

Methods

COSMIC is a prospective phase II trial of IMRT (25 × 2 Gy) and carbon ion boost (8 × 3 GyE). Primary endpoint is mucositis CTC°III, secondary endpoints are local control, progression-free survival, and toxicity. Evaluation of disease response is carried out according to the Response Evaluation Criteria in Solid Tumors (RECIST); toxicity is assessed using NCI CTC v 3.0.

Results

Twenty-nine patients were recruited from 07/2010 to 04/2011, all patients have at least completed first follow-up. Sixteen patients were treated in the R2-group, 13 in the R1-group. All treatments were completed as planned and well tolerated, mucositis CTC grade III was 25% (R2) and 15.4% (R1), no dysphagia CTC grade III was observed, no feeding tubes were necessary. Side-effects rapidly resolved, only 4 patients (13.8%) reported xerostomia grade II at first follow-up. Overall response rate (complete and partial response) according to RECIST in the R2-group is 68.8% at 6–8 weeks post treatment, all patients within this group showed radiological signs of treatment response.

Conclusion

No unexpected toxicity was observed, mucositis rates and other side effects do not differ between patients with visible residual tumor and macroscopically completely resected tumors. Initial treatment response is promising though longer follow-up is needed to assess local control.

Trial registration

Clinical trial identifier NCT 01154270

Dose escalation in prostate cancer using intensity modulated neutron radiotherapy

BACKGROUND AND PURPOSE

Initial promising results of 3D conformal neutron radiotherapy (3D-CNRT) were subsequently limited by high normal tissue toxicities. It is now possible to deliver intensity modulated neutron radiotherapy (IMNRT). The present work compares photon IMRT, 3D-CNRT and IMNRT for three prostate patients to quantify the benefits of IMNRT.

MATERIALS AND METHODS

We compare updated 3D-CNRT plans, IMNRT plans, and conventional IMRT plans by translating neutron DVHs into effective photon DVHs using the dose dependent radiobiological effectiveness (RBE) for each structure. RBE curves are parameterized for a range of normal tissue and prostate tumor values. Generalized equivalent uniform dose (gEUD) and gEUD in 2Gy fractions (gEUD(2)) is calculated for each structure, plan, and parameterization. Rectal sparing and dose to prostate-GTV are compared for 3D-CNRT, IMNRT, and IMRT as a function of normal tissue and prostate RBE.

RESULTS

The closer the RBE values of prostate tumor and normal tissue, the greater the advantage of IMNRT over 3D-CNRT. The rectal sparing achieved using IMNRT ranged from ∼5% to 13% depending upon the choice of RBE for rectum and the α/β value of prostate tumor. IMNRT may provide a theoretical dose advantage over photon IMRT if the α/β value of prostate is 1.5 and the RBEs of prostate and rectum differ by more than 5%. For higher values of prostate α/β any advantages of IMNRT over IMRT could require that the RBEs of prostate and rectum differ by as much as 20%.

CONCLUSIONS

IMNRT provides a clear normal tissue sparing advantage over 3D-CNRT. The advantage increases when the RBEs of the target structure and the normal tissue are similar. This RBE translation method could help identify clinical sites where the dose sparing advantages of IMNRT would allow for the exploitation of the radiobiological advantages of high-LET neutron radiotherapy.

Three-dimensional conformal postoperative radiotherapy in patients with parotid tumors: 10 years' experience at the European Institute of Oncology

Aims and background

Salivary gland malignancies are rare. The aim of our study was to investigate radiotherapy-related toxicity and clinical outcome in patients treated at our division with postoperative radiotherapy (pRT) for parotid tumors.

Methods and study design

Forty-three consecutive patients (32 with primary parotid tumors, 9 with parotid metastases and 2 with recurrent benign diseases) were retrospectively analyzed.

Results

The median follow-up was 28 months. Twenty and 5 patients had a follow-up longer than 2 and 5 years, respectively. Thirty-seven patients were alive and most of them (78%) were free from disease. The local and distant control rates were higher in patients with primary parotid tumors (94% and 87.5%) than in patients with parotid metastases (87.5% and 75%). Grade 3 radiotherapy-related acute toxicity of skin and mucosa was recorded in 20.9% and 28% of patients, respectively. Two patients (4.7%) had grade 4 skin toxicity. Late toxicity data were available for 33 (77%) patients. None of the patients developed severe (grade 3 and 4) late toxicity of soft tissues, skin or temporomandibular joints.

Conclusions

Postoperative radiotherapy is a feasible treatment that was found to be effective mainly in patients with primary parotid tumors. Toxicity was acceptable but could probably be further reduced using more advanced radiotherapy techniques. Longer follow-up is required to achieve definitive results.

Determinants and patterns of survival in adenoid cystic carcinoma of the head and neck, including an analysis of adjuvant radiation therapy

OBJECTIVES

The effect of adjuvant radiation therapy (RT) on survival in patients with adenoid cystic carcinoma (ACC) is much debated. Studies with large numbers of patients and long follow-up are lacking in the literature.

METHODS

We identified 2286 single-primary ACCs of the head and neck treated with surgery in the National Cancer Institute's surveillance, epidemiology, and end results database. The determinants of survival, including the effect of adjuvant RT, were analyzed with a Cox Proportional Hazards Model.

RESULTS

The overall 5-, 10-, 15-, 20-, and 25-year survival rates for patients receiving surgical resection were 77.3%, 59.6%, 44.9%, 35.0%, 25.5%, respectively. In the interval between 10 and 30 years after diagnosis, 111 patients died of ACC, and 137 died of all competing causes combined. Increasing stage caused a decrease in survival that was proportional over time. On multivariable analysis, distant metastasis, lymph node involvement, higher T classification, increasing age, and submandibular gland, or sinus/nasal cavity subsites were each independently associated with decreased overall and cause-specific survival. Adjuvant RT failed to improve overall or cause-specific survival.

CONCLUSIONS

Cause-specific survival continues to decline up to 30 years after diagnosis in ACC of the head and neck. In the interval between 10 and 30 years after diagnosis, patients are nearly as likely to die of ACC as from all competing causes combined. Certain clinicopathological factors are associated with decreased survival. There is no evidence of increased survival in patients receiving adjuvant RT.

Lymphoepithelioma-like carcinoma of the salivary gland: is radiotherapy alone adequate?

Introduction. Lymphoepithelioma-like carcinoma (LELC) of the salivary gland is a rare tumor. Currently, surgery with or without radiotherapy is the recommended treatment for all salivary gland carcinomas. However, in contrast to other high-grade salivary gland carcinomas, LELCs are considered radiosensitive. There are only a few published reports of radiotherapy alone for the treatment of salivary gland LELC. Case. We present two cases of LELC of the salivary gland. One was treated with surgery and postoperative radiotherapy, and the other was given a single cycle of chemotherapy and then radiotherapy. Currently, both patients have no evidence of disease. Conclusion. Radiotherapy as a single modality should be reevaluated. The role of systemic chemotherapy to gain systemic control should be addressed due to noteworthy metastatic disease.

Major and minor salivary gland tumors

Malignant salivary gland tumors are rare. The most common tumor site is the parotid. Aetiologic factors are not clear. Nutrition may be a risk factor, as well as irradiation or a long-standing histologically benign tumor that occurs at youth. Painless swelling of a salivary gland should always be considered as suspicious, especially if no sign of inflammation is present. Signs and symptoms related to major salivary gland tumors differ from those concerning minor salivary gland tumors, as they depend on the different location of the salivary gland. Surgical excision represents the standard option in the treatment of resectable tumors of both major and minor salivary glands. Neutron, heavy ions or proton radiotherapy may be a treatment option for inoperable locoregional disease. Surgery, irradiation or re-irradiation are treatment options for local relapse, whereas radical neck dissection is indicated for regional relapses. Metastatic disease may be either treated with radiotherapy or palliative chemotherapy, depending on the site of metastases. For highly selected patients the employment of anti-androgen therapy is indicated.

Changes in prescribed doses for the Seattle neutron therapy system

From the beginning of the neutron therapy program at the University of Washington Medical Center, the neutron dose distribution in tissue has been calculated using an in-house treatment planning system called PRISM. In order to increase the accuracy of the absorbed dose calculations, two main improvements were made to the PRISM treatment planning system: (a) the algorithm was changed by the addition of an analytical expression of the central axis wedge factor dependence with field size and depth developed at UWMC. Older versions of the treatment-planning algorithm used a constant central axis wedge factor; (b) a complete newly commissioned set of measured data was introduced in the latest version of PRISM. The new version of the PRISM algorithm allowed for the use of the wedge profiles measured at different depths instead of one wedge profile measured at one depth. The comparison of the absorbed dose calculations using the old and the improved algorithm showed discrepancies mainly due to the missing central axis wedge factor dependence with field size and depth and due to the absence of the wedge profiles at depths different from 10 cm. This study concludes that the previously reported prescribed doses for neutron therapy should be changed.

Tumeurs malignes de la parotide: prise en charge multidisciplinaire, rôle de la radiothérapie

The low incidence, the wide histological spectrum and the natural, sometimes slow, evolution of malignant parotid gland tumours do not allow to easily establish the impact of their treatments. At present, clinical data come from retrospective cohort analysis, whereas randomized phase II-III trials are confidential. Moreover conclusions from these studies are controversial. We present here the therapeutic highlights of parotid cancers: surgery, with the particular concern of facial nerve preservation; and adjuvant treatment essentially based on radiotherapy. This review focused on adjuvant care explores the indications and the technical aspects of radiation, as well as the role of concurrent chemotherapy.

Particle beam radiotherapy for head and neck tumors: radiobiological basis and clinical experience

BACKGROUND

Head and neck tumors are often located near critical organs, making it impossible to deliver a dose of conventional radiotherapy high enough to eradicate the disease. Our aim was to review the potential benefits and available clinical experience of particle beam therapy (hadrontherapy) in the treatment of these tumors.

METHODS

A review of the literature was carried out through a MEDLINE search (publications between 1980 and 2005).

RESULTS

A review of the available clinical data shows that particle beam therapy can offer several radiobiological and physical advantages over conventional photon radiotherapy: improved dose distribution permits dose escalation within the target and optimal sparing of normal tissue. Preclinical and clinical studies suggest that there may be benefits to using hadrontherapy for tumors characterized by poor radiosensitivity and critical location. At present, the most used hadrons are protons and, as yet on an experimental basis, carbon ions. It is now well accepted that there are certain indications for using proton therapy for skull base tumors (chordoma and chondrosarcoma), paranasal sinus carcinomas, selected nasopharyngeal tumors, and neutron/ion therapy for salivary gland carcinomas (in particular, adenoid cystic tumors). Its viability in other cases, such as locally advanced squamous cell carcinoma, melanoma, soft tissue sarcoma, and bone sarcoma, is still under investigation.

CONCLUSIONS

Hadrontherapy can be beneficial in the treatment of tumors characterized by poor radiosensitivity and critical location. Further clinical and radiobiological studies are warranted for improved selection of patient population.

Results of carbon ion radiotherapy in 152 patients

PURPOSE

This study summarizes the experience with raster scanned carbon ion radiation therapy (RT) at the Gesellschaft für Schwerionenforschung (GSI), Darmstadt, Germany since 1997.

METHODS AND MATERIALS

Between December 1997 and December 2002, 152 patients were treated at GSI with carbon ion RT. Eighty-seven patients with chordomas and low-grade chondrosarcomas of the skull base received carbon ion RT alone (median dose 60 GyE); 21 patients with unfavorable adenoid cystic carcinomas and 17 patients with spinal (n = 9) and sacrococcygeal (n = 8) chordomas and chondrosarcomas were treated with combined photon and carbon ion RT. Twelve patients received reirradiation with carbon ions with or without photon RT for recurrent tumors. Furthermore, 15 patients with skull base tumors other than chordoma and low-grade chondrosarcoma were treated with carbon ions.

RESULTS

Actuarial 3-year local control was 81% for chordomas, 100% for chondrosarcomas, and 62% for adenoid cystic carcinomas. Local control was obtained in 15/17 patients with spinal (8/9) and sacral (7/8) chordomas or chondrosarcomas and in 11/15 patients with skull base tumors other than chordomas and low-grade chondrosarcomas, respectively. Six of 12 patients who received reirradiation are still alive without signs of tumor progression. Common Toxicity Criteria Grade 4 or Grade 5 toxicity was not observed.

CONCLUSION

Carbon ion therapy is safe with respect to toxicity and offers high local control rates for skull base tumors such as chordomas, low-grade chondrosarcomas, and unfavorable adenoid cystic carcinomas.

Le traitement par neutrons : hadronthérapie partie II : bases physiques et expérience clinique

Neutrons have radiobiological characteristics, which differ from those of conventional radiotherapy beams (photons) and which offer a theoretical advantage over photons to fight radioresistance by the differential relative biological effect of them between normal and tumour tissues. Neutron therapy beneficed of great interest between 1975 and 1985. Many of phase III trials were conducted and indications have been definitively deducted of them. After briefly describing the properties of neutron beams, this review discusses the indication of neutron therapy on the basis of the clinical results. Salivary, prostate tumours and sarcomas are the main indications of neutron therapy. In concern to the prostate cancers, other alternative treatments reduce the neutron therapy field. For sarcomas, the lack of randomised trials limits the impact of the interest of neutrons. For other tumours, the ratio benefice/risk of neutron therapy is inferior to these obtained with photons and they could not be considered like classical indications.

Feasibility and toxicity of combined photon and carbon ion radiotherapy for locally advanced adenoid cystic carcinomas

PURPOSE

To investigate clinical feasibility and toxicity of combined photon and carbon ion radiotherapy in locally advanced adenoid cystic carcinomas (ACC) within a prospective Phase I/II trial.

METHODS AND MATERIALS

Between September 1998 and April 2002, 16 patients with histopathologically proven ACC and residual macroscopic tumor were treated with combined photon RT and a carbon ion boost to the macroscopic tumor. Median total tumor dose within the gross tumor volume (GTV) was 72 GyE. Photon radiation therapy (RT) consisted of fractionated stereotactic RT in 7 patients; 9 patients received stereotactic intensity-modulated RT. Carbon ion boost was delivered by intensity-controlled raster scanning at the heavy ion synchrotron (SIS) at the Heavy Ion Research Center (GSI) in Darmstadt.

RESULTS

Median follow-up was 12 months. Three patients developed locoregional recurrences 9, 11, and 24 months after RT, respectively. Actuarial local control rates were 80.8% and 64.6% at 1 and 3 years, respectively. Overall survival rates were 100% and 83.3% at 1 and 3 years, respectively. Acute side effects greater than Common Toxicity Criteria (CTC) Grade 2 were observed in 2 patients; no patient developed late effects > CTC Grade 2.

CONCLUSIONS

Combined photon and carbon ion RT is feasible and effective in patients with locally advanced ACC. Acute and late toxicity is moderate with respect to the delivered tumor doses and in accordance with the radiobiologic modeling. A Phase III trial is designed.

Radiotherapy for advanced adenoid cystic carcinoma: neutrons, photons or mixed beam?

PURPOSE

To compare retrospectively radiotherapy with neutrons, photons, and a photon/neutron mixed beam in patients with advanced adenoid cystic carcinoma of the head and neck. Local control, survival, distant failure, and complications were analyzed.

MATERIALS AND METHODS

Between 1983 and 1995, 75 patients with inoperable, recurrent, or incompletely resected adenoid cystic carcinoma of the head and neck received radiotherapy that consisted of either fast 14.1 MV DT neutrons (median dose 16 neutron Gy), linac-based photon irradiation (median dose 64 photon Gy), or both (median dose 8 neutron Gy and 32 photon Gy). Follow-up ranged from 1 to 160 months (median 51 months), and the surviving patients had a minimum follow-up of 3 years at the time of analysis.

RESULTS

The actuarial 5-year local control was 75% for neutrons, and 32% for both mixed beam and photons (P = 0.015, log-rank). This advantage for neutrons in local control was not transferred to significant differences in survival (P > 0.1). The survival is dictated by the tumor diseases due to distant metastases occurring in 29 (39%) of the 75 patients. Positive lymph nodes were the only significant factor (P = 0.001) associated with the development of distant metastases although negative lymph nodes did not predict absence of distant metastases, but predicted a delay of occurrence. In multivariate analysis postoperative radiotherapy (P = 0.003) and small tumor size (P = 0.01) were associated with high local control, while primary therapy (P = 0.006) and negative lymph nodes (P = 0.01) were associated with longer survival. While acute toxicity was similar in all three radiotherapy groups, severe late grade 3 and 4 toxicity tended to be more prevalent (P > 0.1) with neutrons (19%) than with mixed beam (10%) and photons (4%).

CONCLUSION

Fast neutron radiotherapy provides higher local control rates than a mixed beam and photons in advanced, recurrent or not completely resected adenoid cystic carcinoma of the major and minor salivary glands. Neutron radiotherapy can be recommended in patients with bad prognosis with gross residual disease (R2), with unresectable tumors, or inoperable tumors. The type of radiation does not impact survival, which is dominated by the high number of distant metastases.

Recoil proton, alpha particle, and heavy ion impacts on microdosimetry and RBE of fast neutrons: analysis of kerma spectra calculated by Monte Carlo simulation

Fast neutrons (FN) have a higher radio-biological effectiveness (RBE) compared with photons, however the mechanism of this increase remains a controversial issue. RBE variations are seen among various FN facilities and at the same facility when different tissue depths or thicknesses of hardening filters are used. These variations lead to uncertainties in dose reporting as well as in the comparisons of clinical results. Besides radiobiology and microdosimetry, another powerful method for the characterization of FN beams is the calculation of total proton and heavy ion kerma spectra. FLUKA and MCNP Monte Carlo code were used to simulate these kerma spectra following a set of microdosimetry measurements performed at the National Accelerator Centre. The calculated spectra confirmed major classical statements: RBE increase is linked to both slow energy protons and alpha particles yielded by (n,α) reactions on carbon and oxygen nuclei. The slow energy protons are produced by neutrons having an energy between 10 keV and 10 MeV, while the alpha particles are produced by neutrons having an energy between 10 keV and 15 MeV. Looking at the heavy ion kerma from <15 MeV and the proton kerma from neutrons <10 MeV, it is possible to anticipate y* and RBE trends.Key words: fast neutron, kerma, microdosimetry, RBE, Monte Carlo.

Osteoradionecrosis of the maxillary-orbital complex after neutron beam radiotherapy

OBJECTIVE

Neutron beam radiotherapy (NRT) has been advocated for treatment of malignant salivary gland tumors and adenoid cystic carcinoma of the paranasal sinuses. The purpose of this study is to determine whether primary or adjuvant NRT results in a significantly increased rate of osteora-dionecrosis (ORN) of the maxillary-orbital complex (MOC).

STUDY DESIGN AND SETTING

All patients who received primary or adjuvant NRT involving the MOC and/or maxillofacial prosthetic rehabilitation at Wayne State University from 1992 to 1997 were evaluated (n = 9).

RESULTS

ORN did not develop in any of the 5 patients who received primary NRT. All 4 patients who received adjuvant NRT after surgical resection had ORN involving the MOC within the irradiated fields.

CONCLUSION

The reported trend of ORN after definitive surgery and NRT shows a markedly increased complication rate.

SIGNIFICANCE

The use of adjuvant NRT after definitive surgical resection involving the MOC should be considered with great caution.

[Use of fast neutrons in the treatment of tumors of the salivary glands: rationale, review of the literature and experience in Orleans]

If low LET radiation therapy (photons, electrons), following radical microscopically and complete surgery can improve results in term of local control from 34 to 74% for salivary gland tumors, local control is more difficult to achieve in advanced tumors and only palliative treatment is usually attempted. In this survey, all the patient series treated worldwide were reviewed. They show an overall control rate of 31% with photon vs 64% with neutron therapy. A prospective randomised trial sponsored by the RTOG and the MRC published in 1988 and reviewed in 1993 showed an overall locoregional complete tumor clearance of 67% for neutrons and 17% for photons (P < 0.005), with 68% and 25% survival at two years for neutrons and photons respectively. This study was closed for ethical reasons. In Orleans, since 1987, 59 patients have been treated. At five years the persistent local control probability was 69.5%, the five-year crude survival probability 66% and the five-year tumor free survival probability was 64.5%. This review provides evidence that surgical treatment for salivary gland tumors should be limited to patients presenting a high likelihood of negative surgical margin and a small risk of facial nerve damage. Others patients should receive neutron radiation therapy alone as definitive treatment.