Intensity modulated radiation therapy for oropharyngeal and oral cavity tumors: clinical use and experience

Hyperbaric oxygen treatment of mandibular osteoradionecrosis: Combined data from the two randomized clinical trials DAHANCA-21 and NWHHT2009-1

PURPOSE

Osteoradionecrosis (ORN) of the mandible is a serious complication of head and neck radiotherapy. This study aims to investigate the effect of hyperbaric oxygen (HBO) treatment on ORN in two randomized, controlled multicentre trials.

METHODS AND MATERIALS

Patients with ORN with indication for surgical treatment were randomised to either group 1: surgical removal of necrotic mandibular bone supplemented by 30 pre- and 10 postoperative HBO exposures at 243 kPa for 90 min each, or group 2: surgical removal of necrotic bone only. Primary outcome was healing of ORN one year after surgery evaluated by a clinically adjusted version of the Common Toxicity Criteria of Adverse Events (CTCAE) v 3.0. Secondary outcomes included xerostomia, unstimulated and stimulated whole salivation rates, trismus, dysphagia, pain, Activities of Daily Living (ADL) and quality of life according to EORTC. Data were combined from two separate trials. Ninety-seven were enrolled and 65 were eligible for the intent-to-treat analysis. The 33% drop-out was equally distributed between groups.

RESULTS

In group 1, 70% (21/30) healed compared to 51% (18/35) in group 2. HBO was associated with an increased chance of healing independent of baseline ORN grade or smoking status as well as improved xerostomia, unstimulated whole salivary flow rate, and dysphagia. Due to insufficient recruitment, none of the endpoints reached a statistically significant difference between groups. ADL data could only be obtained from 50 patients.

CONCLUSION

Hyperbaric oxygen did not significantly improve the healing outcome of osteoradionecrosis after surgical removal of necrotic bone as compared to standard care (70% vs. 51%). This effect is not statistically significant due to the fact that the study was underpowered and is therefore prone to type II error.

Are intraoral stents effective in reducing oral toxicities caused by radiotherapy? A systematic review and meta-analysis

STATEMENT OF PROBLEM

Intraoral stents have been provided to minimize acute and chronic toxicities induced by radiotherapy, including oral mucositis, salivary changes, trismus, radiation-related caries, and osteoradionecrosis. However, a systematic review and meta-analysis is necessary to determine their effectiveness.

PURPOSE

The purpose of this systematic review and meta-analysis was to determine the effectiveness of intraoral stent use and determine whether these prosthetic devices can reduce radiation dosage to nontargeted oral tissues and adverse effects related to head and neck radiation.

MATERIAL AND METHODS

Two independent reviewers made a systematic search for articles published from January 2010 to March 2020 in 3 databases, supplemented by a manual search. Studies were included if they were clinical trials (randomized controlled trials, both prospective and retrospective), published in English, and evaluated radiation dose and oral adverse side effects (acute or chronic) induced by radiotherapy of participants with and without intraoral stents.

RESULTS

The search strategy identified 201 studies; of which, 9 were included. A total of 251 participants were evaluated; of whom, 168 (77.3%) used intraoral stents and 57 (22.7%) were treated with radiotherapy without a prosthetic device. A statistically significant difference was found regarding the use of intraoral stents for preventing oral mucositis (P<.001), salivary changes (P=.003), and trismus (P<.02). A funnel plot showed asymmetry among the differences of means in all selected studies.

CONCLUSIONS

Intraoral stents have a positive effect on preventing oral mucositis. Further clinical trials are needed to address the flaws identified in the present systematic review.

Meridianin C inhibits the growth of YD-10B human tongue cancer cells through macropinocytosis and the down-regulation of Dickkopf-related protein-3

Meridianin C is a marine natural product known for its anti-cancer activity. At present, the anti-tumour effects of meridianin C on oral squamous cell carcinoma are unknown. Here, we investigated the effect of meridianin C on the proliferation of four different human tongue cancer cells, YD-8, YD-10B, YD-38 and HSC-3. Among the cells tested, meridianin C most strongly reduced the growth of YD-10B cells; the most aggressive and tumorigenic of the cell lines tested. Strikingly, meridianin C induced a significant accumulation of macropinosomes in the YD-10B cells; confirmed by the microscopic and TEM analysis as well as the entry of FITC-dextran, which was sensitive to the macropinocytosis inhibitor amiloride. SEM data also revealed abundant long and thin membrane extensions that resemble lamellipodia on the surface of YD-10B cells treated with meridianin C, pointing out that meridianin C-induced macropinosomes was the result of macropinocytosis. In addition, meridianin C reduced cellular levels of Dickkopf-related protein-3 (DKK-3), a known negative regulator of macropinocytosis. A role for DKK-3 in regulating macropinocytosis in the YD-10B cells was confirmed by siRNA knockdown of endogenous DKK-3, which led to a partial accumulation of vacuoles and a reduction in cell proliferation, and by exogenous DKK-3 overexpression, which resulted in a considerable inhibition of the meridianin C-induced vacuole formation and decrease in cell survival. In summary, this is the first study reporting meridianin C has novel anti-proliferative effects via macropinocytosis in the highly tumorigenic YD-10B cell line and the effects are mediated in part through down-regulation of DKK-3.

Long-Term Results of Conventional Radiotherapy versus Accelerated Hyperfractionated Radiotherapy versus Concomitant Radiotherapy and Chemotherapy in Locoregionally Advanced Carcinoma of the Oropharynx

AIMS AND BACKGROUND

To compare conventional fractionation (CF) radiation therapy (RT), arm A, versus a split-course accelerated hyperfractionated schedule (S-AHF), arm B, versus CFRT plus concomitant chemotherapy (CT), arm C, in terms of five-year survival and toxicity for squamous cell tumors of the oropharynx.

METHODS AND STUDY DESIGN

Between January 1993 and June 1998, 192 previously untreated patients with stage III and IV oropharyngeal carcinoma (excluding T1N1 and T2N1) were enrolled in a multicenter randomized phase III trial (ORO 93-01). In arms A and C, 66 to 70 Gy in 33 to 35 fractions was administered five days a week for six and a half to seven weeks. In arm B, the dose delivered was 64 to 67.2 Gy in two fractions of 1.6 Gy every day, five days a week, with a planned two-week split at 38.4 Gy. In arm C the CT regimen consisted of three cycles of carboplatin and 5-fluorouracil (CBDCA 75 mg/m2 on days 1 to 4 and 5-FU 1000 mg/m2 i.v. on days 1 to 4 every 28 days).

RESULTS

No statistically significant difference was found in five-year overall survival (P = 0.39): 21% for arm A, 21% for arm B, and 40% for arm C. Similarly, there was no statistically significant difference in terms of five-year relapse-free survival: 15% for arm A, 17% for arm B, and 36% for arm C. There was a slight trend towards better five-year locoregional control (P = 0.07) for the combined arm: patients without locoregional relapse were 48% in arm C, 21% in arm A and 18% in arm B. Locoregional control was significantly better when arm C was compared with arms A and B combined (P = 0.02; arm A+B 20%; arm C 48%). Distant metastases were fairly balanced in the three arms (A: 14; B: 9; C: 11), with a tendency towards more frequent isolated distant metastasis development in arm C (8 of 11 [72%] versus 7 of 23 [30%] in arms A+B). Five-year second-tumor-free survival was 85%. The 13 second tumors were equally distributed and were mainly correlated with tobacco and alcohol consumption (five lung, two esophagus, two oral cavity, one larynx, one pancreas, one hepatocarcinoma, one myeloma). Arm C showed slightly more G3+ late side effects involving subcutaneous tissues and mucosa, although significant late sequelae were relatively uncommon and the mucosal side effects were mostly transient. The occurrence of persistent G3 xerostomia was comparable in the three treatment arms.

CONCLUSIONS

The results obtained with the combination of CT and RT compared with RT alone did not reach statistical significance, but combined treatment almost doubled the five-year overall survival, relapse-free survival and locoregional control rate. Patients with advanced squamous cell carcinomas of the oropharynx who are medically suitable for the combined approach should be treated with a combination of radiotherapy and chemotherapy. The occurrence of second tumors is relatively common in these patients and may contribute substantially to the causes of death.

Intensity-modulated radiation therapy for head and neck cancer

In head and neck cancer, intensity-modulated radiation therapy (IMRT) makes the use of electron beams for irradiation of the posterior neck obsolete, inherently performs missing tissue compensation, and allows concave and intentionally nonhomogeneous dose distributions. By clinical use of these physical characteristics, salivary or lacrimal glands, optic pathway and auditory structures can be selectively underdosed and good evidence of decreased radiation toxicity is available. Evidence for increased local control is still lacking. Recurrences are mainly located in the high-dose-prescription regions, suggesting the need for even higher doses in these areas. Image-aided design of IMRT dose distribution is an area of intense research. New positron emission tomography and magnetic resonance imaging developments might allow definition of volumes inside the tumor where treatment failure is most likely to occur. If these volumes are small, focused dose escalation of large magnitude can be attempted and the hypothesis of improved local control by IMRT can be tested.

Head and neck cancer pain: systematic review of prevalence and associated factors

OBJECTIVES

Pain is a major symptom in patients with cancer; however information on head and neck cancer related pain is limited. The aim of this review was to investigate the prevalence of pain and associated factors among patients with HNC.

MATERIAL AND METHODS

The systematic review used search of MEDLINE, EMBASE and CINAHL databases to December 2011. Cancers of the oral mucosa, oropharynx, hypopharynx and larynx were included in this review with pain as main outcome. The review was restricted to full research reports of observational studies published in English. A checklist was used to assess the quality of selected studies.

RESULTS

There were 82 studies included in the review and most of them (84%) were conducted in the past ten years. Studies were relatively small, with a median of 80 patients (IQR 44, 154). The quality of reporting was variable. Most studies (77%) used self-administered quality of life questionnaires, where pain was a component of the overall scale. Only 33 studies reported pain prevalence in HNC patients (combined estimate from meta-analysis before (57%, 95% CI 43% - 70%) and after (42%, 95% CI 33% - 50%) treatment. Only 49 studies (60%) considered associated factors, mostly tumour- or treatment-related.

CONCLUSIONS

The study has shown high levels of pain prevalence and some factors associated with higher levels of pain. There is a need for higher quality studies in a priority area for the care of patients with head and neck cancer.

Improved normal tissue sparing in head and neck radiotherapy using biological cost function based-IMRT

Intensity-modulated radiotherapy (IMRT) has reduced the impact of acute and late toxicities associated with head and neck radiotherapy. Treatment planning system (TPS) advances in biological cost function based optimization (BBO) and improved segmentation techniques have increased organ at risk (OAR) sparing compared to conventional dose-based optimization (DBO). A planning study was undertaken to compare OAR avoidance in DBO and BBO treatment planning. Simultaneous integrated boost treatment plans were produced for 10 head and neck patients using both planning systems. Plans were compared for tar get coverage and OAR avoidance. Comparisons were made using the BBO TPS Monte Carlo dose engine to eliminate differences due to inherent algorithms. Target coverage (V95%) was maintained for both solutions. BBO produced lower OAR doses, with statistically significant improvement to left (12.3%, p = 0.005) and right parotid mean dose (16.9%, p = 0.004), larynx V50 Gy (71.0%, p = 0.005), spinal cord (21.9%, p < 0.001) and brain stem dose maximums (31.5%, p = 0.002). This study observed improved OAR avoidance with BBO planning. Further investigations will be undertaken to review any clinical benefit of this improved planned dosimetry.

Shielding effect of a customized intraoral mold including lead material in high-dose-rate 192-Ir brachytherapy for oral cavity cancer

A high-dose-rate (HDR) 192-Ir brachytherapy using a customized intraoral mold is effective for superficial oral cavity cancer, and the surrounding normal tissue is kept away from the radioactive source with gauze pads and/or mouth piece for reducing the dose on the normal tissues. In the Tokushima university hospital, the mold has a lead shield which utilizes the space prepared with sufficient border-molding by a specific dental technique using modeling compound. In HDR 192-Ir brachytherapy using a lead shielded customized intraoral mold, there are no reports measuring the absorbed dose. The purpose of the present study is to measure the absorbed dose and discuss the optimum thickness of lead in HDR 192-Ir brachytherapy using a customized intraoral mold with lead shield using a 1 cm thickness mimic mold. The thickness of lead in the mold could be changed by varying the arrangement of 0.1 cm thickness sheet of the acrylic resin plate and lead. The measured doses at the lateral surface of the mold with thermo-luminescence dosimeter were reduced to 1.12, 0.79, 0.57, 0.41, 0.31, 0.24 and 0.19 Gy and the ratios to the prescription dose were reduced to 56, 40, 29, 21, 16, 12 and 10 percent as lead thickness increased from 0 to 0.6 cm in 0.1 cm increments, respectively. A 0.3 cm thickness lead was considered to be required for a 1 cm thickness mold, and it was necessary to thicken the lead as much as possible with the constraint of limited space in the oral cavity, especially at the fornix vestibule.

Pinus densiflora leaf essential oil induces apoptosis via ROS generation and activation of caspases in YD-8 human oral cancer cells

The leaf of Pinus (P.) densiflora, a pine tree widely distributed in Asian countries, has been used as a traditional medicine. In the present study, we investigated the anticancer activity of essential oil, extracted by steam distillation, from the leaf of P. densiflora in YD-8 human oral squamous cell carcinoma (OSCC) cells. Treatment of YD-8 cells with P. densiflora leaf essential oil (PLEO) at 60 μg/ml for 8 h strongly inhibited proliferation and survival and induced apoptosis. Notably, treatment with PLEO led to generation of ROS, activation of caspase-9, PARP cleavage, down-regulation of Bcl-2, and phosphorylation of ERK-1/2 and JNK-1/2 in YD-8 cells. Treatment with PLEO, however, did not affect the expression of Bax, XIAP and GRP78. Importantly, pharmacological inhibition studies demonstrated that treatment with vitamin E (an anti-oxidant) or z-VAD-fmk (a pan-caspase inhibitor), but not with PD98059 (an ERK-1/2 inhibitor) or SP600125 (a JNK-1/2 inhibitor), strongly suppressed PLEO-induced apoptosis in YD-8 cells and reduction of their survival. Vitamin E treatment further blocked activation of caspase-9 and Bcl-2 down-regulation induced by PLEO. Thus, these results demonstrate firstly that PLEO has anti-proliferative, anti-survival and pro-apoptotic effects on YD-8 cells and the effects are largely due to the ROS-dependent activation of caspases.

A systematic review of orofacial pain in patients receiving cancer therapy

PURPOSE

We present the findings of a structured systematic review of the literature assessing orofacial pain induced by malignant disease and/or its therapy (excluding mucositis). This evaluation of the literature published after the 1989 NIH Development Consensus conference on the oral complications of cancer therapies is an effort to assess the prevalence of pain, quality of life and economic impact, and management strategies for cancer therapy-induced orofacial pain.

METHODS

A systematic medical literature search was conducted with assistance from a research librarian in MEDLINE/PubMed and EMBASE databases for articles published between January 1, 1990 and December 31, 2008. Each study was independently assessed by two reviewers with expertise in the field of oral oncology.

RESULTS

Thirty-nine studies assessed pain in the head and neck region. The measure was commonly embedded in quality of life studies. Most of these studies described pain in head and neck cancer (HNC) patients, which therefore became the focus of the report. Pain is common in patients with HNC and is reported by approximately half of patients prior to cancer therapy, 81% during therapy, 70% at the end of therapy, and by 36% at 6 months after treatment. Pain is experienced beyond the 6-month period by approximately one third of patients and is typically more severe than pre-treatment cancer-induced pain.

CONCLUSIONS

This systematic review identified the presence of pain before cancer therapy, likely attributable to the cancer; an increase in pain during therapy and the common persistence of pain following cancer treatment. Continuing research should use validated tools to prospectively assess orofacial pain, its causes and pathophysiology, and its effect on quality of life and economic impact. Clinical trials of pain management in this setting are also warranted.

Regional relapse after intensity-modulated radiotherapy for head-and-neck cancer

PURPOSE

To evaluate the regional relapse rate in the elective neck using intensity-modulated radiotherapy (IMRT) for head-and-neck cancer.

METHODS AND MATERIALS

We retrospectively analyzed the data from 285 patients treated with IMRT between 2000 and 2008. The median dose prescription to the primary tumor and involved lymph nodes was 69 Gy in 32 fractions. The elective neck was treated simultaneously according to Protocol 1 (multiple dose prescription levels of 56-69 Gy; 2-Gy normalized isoeffective dose, 51-70 Gy; 222 patients) or Protocol 2 (one dose prescription level of 56 Gy; 2-Gy normalized isoeffective dose, 51 Gy; 63 patients). Primary surgery or lymph node dissection was performed before IMRT in 72 (25%) and 157 (55%) patients, respectively. Also, 92 patients (32%) received concomitant chemotherapy. The median follow-up of living patients was 27.4 months (range, 0.3-99).

RESULTS

Regional, local, and distant relapse were observed in 16 (5.6%), 35 (12.3%), and 47 (16.5%) patients, respectively. The 2- and 5-year rate of regional relapse was 7% and 10%, respectively, with a trend favoring Protocol 2 (p = 0.06). Seven isolated regional relapses were detected at a median follow-up of 7.3 months in patients treated with Protocol 1 and none in those treated with Protocol 2. Percutaneous gastrostomy was required more frequently in patients who received Protocol 1 (p = 0.079).

CONCLUSION

Isolated regional relapse is rare after IMRT for head-and-neck cancer. Elective neck node doses >51 Gy for a 2-Gy normalized isoeffective dose do not seem to improve regional control.

Intensity- and energy-modulated electron radiotherapy by means of an xMLC for head and neck shallow tumors

The purpose of this paper is to assess the feasibility of delivering intensity- and energy-modulated electron radiation treatment (MERT) by a photon multileaf collimator (xMLC) and to evaluate the improvements obtained in shallow head and neck (HN) tumors. Four HN patient cases covering different clinical situations were planned by MERT, which used an in-house treatment planning system that utilized Monte Carlo dose calculation. The cases included one oronasal, two parotid and one middle ear tumors. The resulting dose-volume histograms were compared with those obtained from conventional photon and electron treatment techniques in our clinic, which included IMRT, electron beam and mixed beams, most of them using fixed-thickness bolus. Experimental verification was performed with plane-parallel ionization chambers for absolute dose verification, and a PTW ionization chamber array and radiochromic film for relative dosimetry. A MC-based treatment planning system for target with compromised volumes in depth and laterally has been validated. A quality assurance protocol for individual MERT plans was launched. Relative MC dose distributions showed a high agreement with film measurements and absolute ion chamber dose measurements performed at a reference point agreed with MC calculations within 2% in all cases. Clinically acceptable PTV coverage and organ-at-risk sparing were achieved by using the proposed MERT approach. MERT treatment plans, based on delivery of intensity-modulated electron beam using the xMLC, for superficial head and neck tumors, demonstrated comparable or improved PTV dose homogeneity with significantly lower dose to normal tissues. The clinical implementation of this technique will be able to offer a viable alternative for the treatment of shallow head and neck tumors.

Intensity-modulated radiotherapy for recurrent and second primary head and neck cancer in previously irradiated territory

PURPOSE

To evaluate re-irradiation using IMRT for recurrent and second primary head and neck cancer in previously irradiated territory.

MATERIALS AND METHODS

Between 1997 and 2008, 84 patients with recurrent and second primary head and neck cancer were treated with IMRT to a median dose of 69 Gy. Median time interval between initial radiotherapy and re-irradiation was 49.5 (5.2-298.3) months. Salvage surgery preceded re-irradiation in 19 patients; 17 patients received concurrent chemotherapy.

RESULTS

Median follow-up of living patients was 19.8 (1.9-76.1) months. Five-year locoregional control and overall survival were 40% and 20%, respectively. Five-year disease-specific survival and disease-free survival were 29% and 15%, respectively. Stage T4 (p=0.015), time interval between initial treatment and re-irradiation (p=0.011) and hypopharyngeal cancer (p=0.013) were independent prognostic factors for worse overall survival in multivariate analysis. Twenty-six and 11 patients developed Grade 3 acute and late toxicity, respectively. No Grade 5 acute toxicity was encountered. There were 2 fatal vascular ruptures during follow-up.

CONCLUSIONS

High-dose IMRT for recurrent and second primary head and neck cancer in previously irradiated territory leads to approximately 20% long-term survival in a non-selected patient population. Identification of patients who would benefit most of curative IMRT is warranted.

Concurrent chemoradiotherapy with helical tomotherapy for oropharyngeal cancer: a preliminary result

PURPOSE

To review the experience with and evaluate the treatment plan for helical tomotherapy for the treatment of oropharyngeal cancer.

METHODS AND MATERIALS

Between November 1, 2006 and January 31, 2009, 10 histologically confirmed oropharyngeal cancer patients were enrolled. All patients received definitive concurrent chemoradiation with helical tomotherapy. The prescription dose to the gross tumor planning target volume, the high-risk subclinical area, and the low-risk subclinical area was 70 Gy, 63 Gy, and 56 Gy, respectively. During radiotherapy, all patients were treated with cisplatin, 30 mg/m(2), plus 5-fluorouracil (425 mg/m(2))/leucovorin (30 mg/m(2)) intravenously weekly. Toxicity of treatment was scored according to the Common Terminology Criteria for Adverse Events, version 3.0. Several parameters, including maximal or median dose to critical organs, uniformity index, and conformal index, were evaluated from dose-volume histograms.

RESULTS

The mean survival was 18 months (range, 7-22 months). The actuarial overall survival, disease-free survival, locoregional control, and distant metastasis-free rates at 18 months were 67%, 70%, 80%, and 100%, respectively. The average for uniformity index and conformal index was 1.05 and 1.26, respectively. The mean of median dose for right side and left side parotid glands was 23.5 and 23.9 Gy, respectively. No Grade 3 toxicity for dermatitis and body weight loss and only one instance of Grade 3 mucositis were noted.

CONCLUSION

Helical tomotherapy achieved encouraging clinical outcomes in patients with oropharyngeal carcinoma. Treatment toxicity was acceptable, even in the setting of concurrent chemotherapy. Long-term follow-up is needed to confirm these preliminary findings.

Acute normal tissue reactions in head-and-neck cancer patients treated with IMRT: influence of dose and association with genetic polymorphisms in DNA DSB repair genes

PURPOSE

To investigate the association between dose-related parameters and polymorphisms in DNA DSB repair genes XRCC3 (c.-1843A>G, c.562-14A>G, c.722C>T), Rad51 (c.-3429G>C, c.-3392G>T), Lig4 (c.26C>T, c.1704T>C), Ku70 (c.-1310C>G), and Ku80 (c.2110-2408G>A) and the occurrence of acute reactions after radiotherapy.

MATERIALS AND METHODS

The study population consisted of 88 intensity-modulated radiation therapy (IMRT)-treated head-and-neck cancer patients. Mucositis, dermatitis, and dysphagia were scored using the Common Terminology Criteria (CTC) for Adverse Events v.3.0 scale. The population was divided into a CTC0-2 and CTC3+ group for the analysis of each acute effect. The influence of the dose on critical structures was analyzed using dose-volume histograms. Genotypes were determined by polymerase chain reaction (PCR) combined with restriction fragment length polymorphism or PCR-single base extension assays.

RESULTS

The mean dose (D(mean)) to the oral cavity and constrictor pharyngeus (PC) muscles was significantly associated with the development of mucositis and dysphagia, respectively. These parameters were considered confounding factors in the radiogenomics analyses. The XRCC3c.722CT/TT and Ku70c.-1310CG/GG genotypes were significantly associated with the development of severe dysphagia (CTC3+). No association was found between the investigated polymorphisms and the development of mucositis or dermatitis. A risk analysis model for severe dysphagia, which was developed based on the XRCC3c.722CT/TT and Ku70c.-1310CG/GG genotypes and the PC dose, showed a sensitivity of 78.6% and a specificity of 77.6%.

CONCLUSIONS

The XRCC3c.722C>T and Ku70c.-1310C>G polymorphisms as well as the D(mean) to the PC muscles were highly associated with the development of severe dysphagia after IMRT. The prediction model developed using these parameters showed a high sensitivity and specificity.

Helical Tomotherapy for Brain Metastases: Dosimetric Evaluation of Treatment Plans and Early Clinical Results

The purpose of this study was to evaluate the feasibility and treatment plans of intensity-modulated radiation therapy using helical tomotherapy (HT) for brain metastases. Twenty-three patients with 1 to 4 brain metastases were treated with H T. In combination with whole-brain radiotherapy ( simultaneous plans), metastatic lesions, and the whole brain were treated with 50 Gy and 30 Gy, respectively, in 10 fractions, with a simultaneous integrated boost technique. In patients treated for brain metastases alone ( focal plans), metastatic lesions were treated with 35 or 37.5 Gy in 5 fractions. The treatment plans were compared regarding the conformation number (CN) and homogeneity index (HI), and differences in these indexes between simultaneous and focal plans were examined by Student's t-test. Seven and 16 patients were treated with simultaneous plans and focal plans, respectively. The mean ± SD of CN and HI values were 0.75 ± 0.13 and 0.063 ± 0.042, respectively, for simultaneous plans, and 0.73 ± 0.12 and 0.052 ± 0.023, respectively, for focal plans. The CN and HI between the two plans were not significantly different. Response rates in 13 patients with follow-up imaging were approximately 90% for both plans and the local control rate at 1 year was 69%. One patient with a huge tumor (34.0 cc) and WHO performance status 3 treated with focal plans experienced severe headache, requiring prolongation of the treatment time, and died at 8 days after completion of treatment. The exact cause of deterioration was uncertain as no radiological investigation was performed in this patient. No late complications were observed during follow-up periods up to 20 months. HT is a viable non-invasive technique for treatment of brain metastases and achieves high accuracy in terms of dose conformity and homogeneity.

Radiotherapy for the management of locally advanced squamous cell carcinoma of the head and neck

BACKGROUND

Squamous cell carcinomas of the head and neck (SCCHN) affect approximately 35 000 people in the United States yearly. Although survival has improved with advances in therapy, patients with advanced stages of SCCHN continue to have a poor prognosis. An understanding of rationale for treatment selection, newer developments in therapy, and treatment toxicity is critical.

METHODS

Standard methods of treating locally advanced SCCHN are reviewed. Advances in medical and radiotherapeutic management are discussed and the toxicities of therapy are described.

RESULTS

Postoperative chemoradiation is used in patients with high-risk characteristics. Induction chemotherapy and altered fractionation radiation treatment have been evaluated as alternatives to definitive chemo-radiotherapy. Targeted agents such as cetuximab may prove to increase survival with minimal increase in toxicity profile. Technological improvements such as the use of intensity-modulated radiation treatment have proven to decrease some debilitating side effects from radiation treatment.

CONCLUSIONS

Locally advanced SCCHN continues to present a therapeutic challenge. Survival, local control, and quality of life are all goals of treatment. The optimal method of treating locally advanced SCCHN is the subject of ongoing research. Long-term side effects can be minimized with the use of newer technologies and with careful treatment planning.

Intensity-modulated radiotherapy for cervical lymph node metastases from unknown primary cancer

PURPOSE

To compare the effectiveness of intensity-modulated radiotherapy (IMRT) and conventional (two-dimensional) radiotherapy in the treatment of cervical lymph node metastases from unknown primary cancer (UPC).

METHODS AND MATERIALS

Between February 2003 and September 2006, 23 patients with UPC of squamous cell carcinoma were treated with IMRT. Extended putative mucosal and bilateral nodal sites were irradiated to a median dose of 66 Gy. In 19 patients, IMRT was performed after lymph node dissection, and in 4 patients primary radiotherapy was given. The conventional radiotherapy group (historical control group) comprised 18 patients treated to a median dose of 66 Gy between August 1994 and October 2003.

RESULTS

Twenty patients completed treatment. As compared with conventional radiotherapy, the incidence of Grade 3 acute dysphagia was significantly lower in the IMRT group (4.5% vs. 50%, p = 0.003). By 6 months, Grade 3 xerostomia was detected in 11.8% patients in the IMRT group vs. 53.4% in the historical control group (p = 0.03). No Grade 3 dysphagia or skin fibrosis was observed after IMRT but these were noted after conventional radiotherapy (26.7%, p = 0.01) and 26.7%, p = 0.03) respectively). With median follow-up of living patients of 17 months, there was no emergence of primary cancer. One patient had persistent nodal disease and another had nodal relapse at 5 months. Distant metastases were detected in 4 patients. The 2-year overall survival and distant disease-free probability after IMRT did not differ significantly from those for conventional radiotherapy (74.8% vs. 61.1% and 76.3% vs. 68.4%, respectively).

CONCLUSIONS

Use of IMRT for UPC resulted in lower toxicity than conventional radiotherapy, and was similar in efficacy.

Correlation between saliva production and quality of life measurements in head and neck cancer patients treated with intensity-modulated radiotherapy

PURPOSE

To investigate the strength of correlation between measured saliva flow rates and various toxicity endpoints commonly used in head and neck cancer (HNC) treatment.

MATERIALS AND METHODS

All patients enrolled in a phase II study using intensity modulated radiotherapy (IMRT) for HNC treatment underwent whole mouth saliva flow measurements (stimulated and unstimulated). They were also assessed for salivary gland toxicity using Radiation Therapy Oncology Group (RTOG) late toxicity grading and 9 items representing patient-graded toxicities from 2 questionnaires (Xerostomia questionnaire and University of Washington quality of life). For each patient, saliva flow rates and quality of life (QOL) data were collected preradiotherapy (RT) and at 3 intervals post-RT (3, 6, and 12 months).

RESULTS

A total of 188 sets of coregistered data were obtained for 47 patients over a period of approximately 4 years. Saliva production and mean QOL dropped significantly immediately after RT, but there was a statistically significant recovery in both parameters between 3- and 12-month post-RT. By 12 months, post-RT the mean QOL scores had returned to pre-RT baseline, although mean stimulated saliva production remained 58% below baseline.

CONCLUSION

Patients with HNC treated with IMRT experienced a small drop in QOL which recovered to baseline by 12 months post-RT. There was no statistically significant correlation seen between global health-related QOL scores and stimulated saliva production rates in the post-RT period.

Experience of high-dose-rate brachytherapy for head and neck cancer treated by a customized intraoral mold technique

Radiotherapy of head and neck cancer has become more successful with the advances in treatment modalities and use of a multidisciplinary approach. Higher quality treatment and a team approach to radiotherapy have thus been required for head and neck cancer. This study presents the clinical experience of high-dose-rate (HDR) brachytherapy for head and neck cancer treated by a customized intraoral mold technique. Two patients are reported for whom we created dental prostheses as the radiation carriers for HDR brachytherapy of their head and neck cancers. HDR brachytherapy with the dental prostheses reported here was feasible and effective for eradicating the head and neck cancer. It has been demonstrated that HDR brachytherapy using a customized intraoral technique can be a treatment option for patients who are not candidates for surgery or external irradiation. It is strongly suggested that specialized dentists are needed who are familiar with not only the anatomy and function of the head and neck region but also radiotherapy. Dental radiologists should take responsibility for constructing irradiation prostheses. If they do, they have the potential to improve the quality of life of patients who undergo radiotherapy for head and neck cancer.

On the performances of different IMRT Treatment Planning Systems for selected paediatric cases

Background

To evaluate the performance of seven different TPS (Treatment Planning Systems: Corvus, Eclipse, Hyperion, KonRad, Oncentra Masterplan, Pinnacle and PrecisePLAN) when intensity modulated (IMRT) plans are designed for paediatric tumours.

Methods

Datasets (CT images and volumes of interest) of four patients were used to design IMRT plans. The tumour types were: one extraosseous, intrathoracic Ewing Sarcoma; one mediastinal Rhabdomyosarcoma; one metastatic Rhabdomyosarcoma of the anus; one Wilm's tumour of the left kidney with multiple liver metastases. Prescribed doses ranged from 18 to 54.4 Gy. To minimise variability, the same beam geometry and clinical goals were imposed on all systems for every patient. Results were analysed in terms of dose distributions and dose volume histograms.

Results

For all patients, IMRT plans lead to acceptable treatments in terms of conformal avoidance since most of the dose objectives for Organs At Risk (OARs) were met, and the Conformity Index (averaged over all TPS and patients) ranged from 1.14 to 1.58 on primary target volumes and from 1.07 to 1.37 on boost volumes. The healthy tissue involvement was measured in terms of several parameters, and the average mean dose ranged from 4.6 to 13.7 Gy. A global scoring method was developed to evaluate plans according to their degree of success in meeting dose objectives (lower scores are better than higher ones). For OARs the range of scores was between 0.75 ± 0.15 (Eclipse) to 0.92 ± 0.18 (Pinnacle³ with physical optimisation). For target volumes, the score ranged from 0.05 ± 0.05 (Pinnacle³ with physical optimisation) to 0.16 ± 0.07 (Corvus).

Conclusion

A set of complex paediatric cases presented a variety of individual treatment planning challenges. Despite the large spread of results, inverse planning systems offer promising results for IMRT delivery, hence widening the treatment strategies for this very sensitive class of patients.

Monte Carlo–based dosimetry of head-and-neck patients treated with SIB-IMRT

PURPOSE

To evaluate the accuracy of previously reported superposition/convolution (SC) dosimetric results by comparing with Monte Carlo (MC) dose calculations for head-and-neck intensity-modulated radiation therapy (IMRT) patients treated with the simultaneous integrated boost technique.

METHODS AND MATERIALS

Thirty-one plans from 24 patients previously treated on a phase I/II head-and-neck squamous cell carcinoma simultaneous integrated boost IMRT protocol were used. Clinical dose distributions, computed with an SC algorithm, were recomputed using an EGS4-based MC algorithm. Phantom-based dosimetry quantified the fluence prediction accuracy of each algorithm. Dose-volume indices were used to compare patient dose distributions.

RESULTS AND DISCUSSION

The MC algorithm predicts flat-phantom measurements better than the SC algorithm. Average patient dose indices agreed within 2.5% of the local dose for targets; 5.0% for parotids; and 1.9% for cord and brainstem. However, only 1 of 31 plans agreed within 3% for all indices; 4 of 31 agreed within 5%. In terms of the prescription dose, 4 of 31 plans agreed within 3% for all indices, whereas 28 of 31 agreed within 5%.

CONCLUSIONS

Average SC-computed doses agreed with MC results in the patient geometry; however deviations >5% were common. The fluence modulation prediction is likely the major source of the dose discrepancy. The observed dose deviations can impact dose escalation protocols, because they would result in shifting patients to higher dose levels.

Comparing step-and-shoot IMRT with dynamic helical tomotherapy IMRT plans for head-and-neck cancer

PURPOSE

The goal of this planning study was to compare step-and-shoot intensity-modulated radiotherapy (IMRT) plans with helical dynamic IMRT plans for oropharynx patients on the basis of dose distribution.

METHODS AND MATERIALS

Five patients with oropharynx cancer had been previously treated by step-and-shoot IMRT at the University Medical Centre Utrecht, The Netherlands, applying five fields and approximately 60-90 segments. Inverse planning was carried out using Plato, version 2.6.2. For each patient, an inverse IMRT plan was also made using Tomotherapy Hi-Art System, version 2.0, and using the same targets and optimization goals. Statistical analysis was performed by a paired t test.

RESULTS

All tomotherapy plans compared favorably with the step-and-shoot plans regarding sparing of the organs at risk and keeping an equivalent target dose homogeneity. Tomotherapy plans in particular realized sharper dose gradients compared with the step-and-shoot plans. The mean dose to all parotid glands (n = 10) decreased on average 6.5 Gy (range, -4 to 14; p = 0.002). The theoretical reduction in normal tissue complication probabilities in favor of the tomotherapy plans depended on the parotid normal tissue complication probability model used (range, -3% to 32%).

CONCLUSION

Helical tomotherapy IMRT plans realized sharper dose gradients compared with the clinically applied step-and shoot plans. They are expected to be able to reduce the parotid normal tissue complication probability further, keeping a similar target dose homogeneity.

A comparison of mean parotid gland dose with measures of parotid gland function after radiotherapy for head-and-neck cancer: implications for future trials

PURPOSE

To determine the most adequate parameter to measure the consequences of reducing the parotid gland dose.

METHODS AND MATERIALS

One hundred eight patients treated with radiotherapy for various malignancies of the head and neck were prospectively evaluated using three methods. Parotid gland function was objectively determined by measuring stimulated parotid flow using Lashley cups and scintigraphy. To assess xerostomia-related quality of life, the head-and-neck cancer module European Organization for Research and Treatment of Cancer QLQ (Quality of Life Questionnaire) H&N35 was used. Measurements took place before radiotherapy and 6 weeks and 12 months after the completion of radiotherapy. Complication was defined for each method using cutoff values. The correlation between these complications and the mean parotid gland dose was investigated to find the best measure for parotid gland function.

RESULTS

For both flow and scintigraphy data, the best definition for objective parotid gland toxicity seemed to be reduction of stimulated parotid flow to < or =25% of the preradiotherapy flow. Of all the subjective variables, only the single item dry mouth 6 weeks after radiotherapy was found to be significant. The best correlation with the mean parotid gland dose was found for the stimulated flow measurements. The predictive ability was the highest for the time point 1 year after radiotherapy. Subjective findings did not correlate with the mean parotid dose.

CONCLUSIONS

Stimulated flow measurements using Lashley cups, with a complication defined as flow < or =25% of the preradiotherapy output, correlated best with the mean parotid gland dose. When reduction of the mean dose to the parotid gland is intended, the stimulated flow measurement is the best method for evaluating parotid gland function.

Implications of radiation dosimetry of the mandible in patients with carcinomas of the oral cavity and nasopharynx treated with intensity modulated radiation therapy

Intensity modulated radiation therapy (IMRT) is a newer method of delivering highly conformal, salivary gland sparing radiation treatment that is finding increasing applications in head and neck malignancies. However, the radiation dose distribution to the mandible is rarely considered with IMRT, and the potential risks of osteoradionecrosis or osseointegrated implant failure are not well characterized for this modality. In a series of 10 patients with oral cavity and nasopharyngeal cancers who previously underwent IMRT, examination of the three-dimensional mandibular dose distribution was undertaken. The findings indicate a modest potential risk of osteoradionecrosis and osseointegrated implant failure in cases where IMRT optimization constraints are not specifically aimed at sparing the mandibular bone. Significantly higher mandibular doses (P < 0.04) were received in cases of oral cavity as opposed to nasopharyngeal cancers with IMRT. Efforts to optimize IMRT to further reduce doses to the mandible should be considered, and development of software tools to integrate three-dimensional dose distributions into planning of post-radiotherapy osseointegration would be beneficial.

Phenomenologic model describing flow reduction for parotid gland irradiation with intensity-modulated radiotherapy: Evidence of significant recovery effect

OBJECTIVE

To develop a model describing the relationship between the parotid gland radiation dose and salivary flow reduction. Salivary function was described by the "relative flow reduction" (RFR)-a continuous variable in contrast to the traditional binary response used in normal tissue complication probability estimations.

METHODS AND MATERIALS

Twenty-three patients with squamous cell carcinoma of the head and neck who were treated with intensity-modulated radiotherapy (RT) were the subject of this study. Of these patients, 19 had sufficiently long follow-up to be eligible for analysis. All were treated with curative intent, most (14 of 19) in the postoperative setting. The planning objectives were to deliver a mean dose of 50, 60, or 70 Gy, respectively, to low-risk microscopic, high-risk microscopic, and gross disease areas, while maintaining a mean dose of < or =20 Gy to the spared portion of one or both parotid glands. The mean dose to all parotid glands (right and left) was 30.2 Gy. All submandibular glands received >50 Gy when not surgically removed. Whole-mouth saliva collections, including both stimulated and unstimulated saliva flow, were obtained before treatment and at regular intervals after RT. These measurements were converted to the RFR by comparing the posttreatment and pretreatment flow rates. Any follow-up flow rates greater than baseline were scored as 0 relative reduction. We used Lyman's model to relate the equivalent uniform dose to RFR at various points for each patient. The equivalent uniform dose was calculated using the linear quadratic model, with an assumed alpha/beta ratio of 3 Gy for the parotid gland. Measurements were modeled 1-3 months after RT (early) and >6 months after RT (late), and using the best and worst measurements, regardless of when measured.

RESULTS

Fitting the Lyman model to RFR data of unstimulated flow revealed a statistically significant dose-complication relationship. We observed a stepwise reduction in flow, with the threshold dose D(50) at 2 Gy per fraction (D(50)) increasing from 12.4 Gy (early) to 43.9 Gy (late). For the worst and best flow measurements, the corresponding D(50) (2 Gy/fr) was 13.0 Gy and 40.1 Gy, respectively. For most stimulated flow measurements, a weak relationship was found between the RFR and equivalent uniform dose. In those cases, the model did not yield a statistically significant description of the data. However, in the case of late measurements, the relationship was statistically significant and similar to that seen in the unstimulated cases, with a D(50) (2 Gy/fr) of 47.5 Gy.

CONCLUSION

We observed a strong relationship between the generalized mean parotid gland dose and RFR. The threshold dose increased markedly between the early and late measurements, indicating a statistically significant recovery effect in this tissue. Compared with unstimulated flow, the RFR for stimulated flow was not described as well by the model, because the effect of the stimulant was not included in the model.

Radiation Therapy With or Without Concurrent Low-Dose Daily Chemotherapy in Locally Advanced, Nonmetastatic Squamous Cell Carcinoma of the Head and Neck

Purpose

To retrospectively investigate the difference between conventionally fractionated (CF) and hyperfractionated (Hfx) radiation therapy (RT), with and without either daily cisplatin (CDDP) or carboplatin (CBDCA), in patients with locally advanced squamous cell carcinoma of the head and neck (SCCHN) enrolled onto two consecutive prospective randomized studies.

Patients and Methods

Treatment consisted of CF RT (70 Gy, group 1), CF RT and either daily CDDP (6 mg/m2) or daily CBDCA (25 mg/m2; group 2), Hfx RT (77 Gy, 1.1 Gy bid; group 3), or Hfx RT and daily CDDP (group 4).

Results

Hfx RT plus CDDP achieved better overall survival (OS) and local recurrence-free survival (LRFS) than any other group. There was an insignificant difference favoring Hfx RT over CF RT, either alone or in combination with CDDP or CBDCA, regarding both OS (P = .058 and P = .051, respectively) and LRFS (P = .088 and P = .091, respectively). No difference was seen between CF RT plus chemotherapy (CHT) and Hfx RT alone regarding either OS (P = .32) or LRFS (P = .48). Regional recurrence-free survival was similar in the four treatment groups. CF RT plus CHT and Hfx RT plus CDDP achieved better distant metastasis-free survival than CF RT and Hfx RT. High-grade toxicity was significantly more frequent in Hfx RT plus CDDP than in any other group, except in the Hfx RT group. Hfx RT led to significantly more acute toxicity and xerostomia than CF RT plus CHT. Hfx RT was more toxic than CF RT, either alone or with concurrent CHT.

Conclusion

Results of this study show that there may be a therapeutic benefit for CF RT plus CHT over Hfx RT plus CDDP in patients with SCCHN, but this cannot be firmly established without a larger and well-planned controlled trial.

A preliminary study of the role of modulated electron beams in intensity modulated radiotherapy, using automated beam orientation and modality selection

PURPOSE

To develop an algorithm for optimal beam arrangement selection in intensity-modulated radiotherapy (IMRT) of mixed photon and electron beams. To apply this algorithm to study the utility of modulated electron beams in the context of IMRT planning.

METHODS AND MATERIALS

The optimization algorithm selects, for a user-specified number of beams, the optimal IMRT arrangement (beam orientations, and photon/electron modality for each orientation) using a novel fast heuristic intensity modulation procedure. The algorithm was employed to select optimal beam arrangements for breast (two, four, and six axial beams) and head-and-neck (three, four, five, and seven nonaxial beams) cases.

RESULTS

For the two cases, increasing the number of selected beams: (1) increased the number of electron beams for the breast case, but not more than one electron beam was selected for the head-and-neck case; (2) decreased critical structure doses for both cases; and (3) decreased target homogeneity for the breast case, but improved it for the head-and-neck case.

CONCLUSIONS

In the two cases analyzed using the selection algorithm, the primary role of modulated electrons differs based on treatment site-normal tissue dose reduction in breast and target homogeneity improvement in head and neck. Although this preliminary study with two cases appears to suggest that the role of intensity-modulated electrons differs based on treatment site, further investigation of large numbers of cases and varied treatment sites are required to establish a definitive conclusion.

Intensity-modulated radiation therapy for oropharyngeal carcinoma: impact of tumor volume

PURPOSE

To assess the therapeutic outcomes in oropharyngeal cancer patients treated with intensity-modulated radiotherapy (IMRT) and analyze the impact of primary gross tumor volume (GTV) and nodal GTV (nGTV) on survival and locoregional control rates.

METHODS AND MATERIALS

Between February 1997 and September 2001, 74 patients with squamous cell carcinoma of the oropharynx were treated with IMRT. Thirty-one patients received definitive IMRT; 17 also received platinum-based chemotherapy. Forty-three patients received combined surgery and postoperative IMRT. The median follow-up for all patients was 33 months (range, 9-60 months). Fifty-two patients (70.3%) had Stage IV disease, 17 patients (23%) had Stage III, 3 patients (4.1%) had Stage II, and 2 patients (2.7%) had Stage I tumors. The mean prescription dose was 70 and 66 Gy, respectively, for the definitive and postoperative cohorts. The daily fraction dose was either 1.9 or 2 Gy, five times weekly. The GTV and/or nGTV were determined and derived using the Computational Environment for Radiotherapy Research, a free software package developed at Washington University. The mean GTV was 30.5 +/- 22.3 cm(3), and the mean nGTV was 23.2 +/- 20.6 cm(3).

RESULTS

Ten locoregional failures were observed. Six patients died of disease and three died of concurrent disease. Distant metastasis developed in 6 patients. The 4-year estimate of overall survival was 87%, and the 4-year estimate of disease-free survival was 81% (66% in the definitive vs. 92% in the postoperative RT group). The 4-year estimate of locoregional control was 87% (78% in the definitive vs. 95% in the postoperative RT group); the 4-year estimate of distant metastasis-free survival was 90% (84% in the definitive vs. 94% in the postoperative group). Multivariate analysis showed that GTV and nGTV were independent risk factors determining locoregional control and disease-free survival for definitive oropharyngeal IMRT patients. The worst late toxicities documented were as follows: 32 patients with Grade 1 and 9 with Grade 2 xerostomia; 2 with Grade 1 and 1 with Grade 2 skin toxicity; 3 with Grade 1 late mucositis; and 3 with Grade 1 trismus. Seventeen patients required gastrostomy tube placement.

CONCLUSION

IMRT is an effective treatment modality for locally advanced oropharyngeal carcinoma. The GTV and nGTV are the most important factors predictive of therapeutic outcome.

Preservation of oral health-related quality of life and salivary flow rates after inverse-planned intensity- modulated radiotherapy (IMRT) for head-and-neck cancer

PURPOSE

To assess whether comprehensive bilateral neck intensity-modulated radiotherapy (IMRT) for head-and-neck cancer results in preserving of oral health-related quality of life and sparing of salivary flow in the first year after therapy.

METHODS AND MATERIALS

Twenty-three patients with head-and-neck cancer (primary sites: nasopharynx [5], oral cavity [12], oropharynx [3], and all others [3]) were accrued to a Phase I-II trial. Inverse planning was carried out with the following treatment goals: at least 1 spared parotid gland (defined as the volume of parotid gland outside the planning target volume [PTV]) to receive a median dose of less than 20 Gy; spinal cord, maximum 45 Gy; PTV(1) to receive a median dose of 50 Gy; PTV(2) to receive a median dose of 60 Gy (postoperative setting, n = 15) or 66-70 Gy (definitive radiotherapy setting, n = 8). Treatment was delivered with 6 and 15 MV photons using a "step-and-shoot" technique on a Varian 2300 EX linac with 120-leaf Millenium MLC. Unstimulated and stimulated whole-mouth salivary flow rates were measured, and patients completed the University of Washington instrument (UWQOL) and a separate xerostomia questionnaire (XQOL) in follow-up.

RESULTS

Early functional outcome end point data are available at the 1-, 3-, and 12-month follow-up time points for 22, 22, and 18 patients, respectively. The combined mean parotid dose was 30.0 Gy (95% confidence interval: 26.9-33.1). The differences from baseline in mean overall UWQOL scores at 1, 3, and 12 months postradiotherapy were -0.24, 0.32, and 4.28, not significantly different from zero (p = 0.89, p = 0.87, p = 0.13). None of the UWQOL individual domain scores related to oral health (pain, eating-chewing, eating-swallowing, and speech) at 1, 3, or 12 months were significantly different from baseline. Both unstimulated and stimulated whole-mouth flow was variably preserved. Unstimulated salivary flow at 1 and 12 months was inversely correlated with combined mean parotid dose (p = 0.014, p = 0.0007), whereas stimulated salivary flow rates at 3 and 12 months were also correlated with combined mean parotid dose (p = 0.025, p = 0.0016). Combined maximum parotid dose was correlated with unstimulated flow rate at 12 months (p = 0.02, r = -0.56) and stimulated flow rate at 1 and 12 months (p = 0.036, r = -0.45; p = 0.0042, r = -0.66). The proportion of patients reporting total XQOL scores of 0 or 1 (no or mild xerostomia) did not diminish significantly from baseline at 1, 3, or 12 months (p = 0.72, p = 0.51, p = 1.0). Unstimulated and stimulated flow at 1 month was inversely correlated with total XQOL score at 12 months (p = 0.025, p = 0.029).

CONCLUSIONS

Oral health-related quality of life (HRQOL) was highly preserved in the initial 12 months after IMRT, as assessed with separate, validated instruments for xerostomia-specific quality of life and oral HRQOL. In general, patients with better-preserved unstimulated salivary flow rates tended to report lower xerostomia scores. Whole-mouth salivary flow rates post IMRT were inversely correlated with combined mean parotid doses. Longer follow-up is required to assess to what extent HRQOL is favorably maintained.

Level II lymph nodes and radiation-induced xerostomia

PURPOSE

To investigate the influence of the cranial border of electively irradiated Level II lymph nodes on xerostomia in patients with oropharyngeal cancer using three-dimensional conformal and intensity-modulated radiotherapy (3D-CRT and IMRT).

METHODS AND MATERIALS

The target volumes and organs at risk were delineated on the planning CT scans of 12 patients. Two elective target volumes were delineated. The first had the transverse process of the C1 atlas and the second had the transverse process of the C2 axis as cranial border of the Level II lymph nodes. 3D-CRT and IMRT planning were performed for both elective volumes, resulting in two plans per patient and technique, called the C1 and C2 plans, respectively. Irradiation of the ipsilateral elective volume up to C1 and the contralateral up to C2 was also performed for IMRT. The normal tissue complication probability (NTCP) for xerostomia 1 year after RT was calculated using the parotid mean dose.

RESULTS

The average mean dose +/- standard deviation (SD) to the contralateral parotid gland was reduced from 33 +/- 5 Gy for the IMRT C1 plans to 26 +/- 4 Gy for the IMRT C2 plans and from 51 +/- 6 Gy to 49 +/- 7 Gy for the 3D-CRT C1 and C2 plans, respectively. The associated NTCP +/- SD for xerostomia was 38% +/- 10% for IMRT C1 plans and 24% +/- 6% for IMRT up to C2 on the contralateral side, regardless of which cranial border was irradiated on the ipsilateral side. For the 3D-CRT C1 and C2 plans, an NTCP value of 74% +/- 12% and 71% +/- 15% was obtained, respectively. The NTCP for xerostomia of the ipsilateral parotid gland was 53% +/- 17% and 45% +/- 20% for the IMRT C1 and C2 plans and 89% +/- 11% and 87% +/- 12% for the 3D-CRT C1 and C2 plans, respectively.

CONCLUSION

Lowering the cranial border of the Level II lymph nodes from C1 to C2, in the case of bilateral elective neck irradiation, could be considered on the contralateral side when the risk of metastasis on that side is very low. This is especially true when IMRT is used, because the relative reduction of NTCP for xerostomia 1 year after RT could be up to 68% compared with conventional conformal RT up to C1.

Intensity-modulated radiation therapy for head-and-neck cancer: the UCSF experience focusing on target volume delineation

PURPOSE

To review the University of California-San Francisco (UCSF) experience of using intensity-modulated radiation therapy (IMRT) to treat head-and-neck cancer focusing on the importance of target volume delineation and adequate target volume coverage.

METHODS AND MATERIALS

Between April 1995 and January 2002, 150 histologically confirmed patients underwent IMRT for their head-and-neck cancer at our institution. Sites included were nasopharynx 86, oropharynx 22, paranasal sinus 22, thyroid 6, oral tongue 3, nasal cavity 2, salivary 2, larynx 2, hypopharynx 1, lacrimal gland 1, skin 1, temporal bone 1, and trachea 1. One hundred seven patients were treated definitively with IMRT +/- concurrent platinum chemotherapy (92/107), whereas 43 patients underwent gross surgical resection followed by postoperative IMRT +/- concurrent platinum chemotherapy (15/43). IMRT was delivered using three different techniques: 1) manually cut partial transmission blocks, 2) computer-controlled auto-sequencing segmental multileaf collimator, and 3) sequential tomotherapy using dynamic multivane intensity-modulating collimator. Forty-two patients were treated with a forward plan, 102 patients with an inverse plan, and 6 patients with both forward and inverse plans. The gross target volume (GTV) was defined as tumor detected on physical examination or imaging studies. In postoperative cases, the GTV was defined as the preoperative gross tumor volume. The clinical target volume (CTV) included all potential areas at risk for microscopic tumor involvement by either direct extension or nodal spread including a margin for patient motion and setup errors. The average prescription doses to the GTV were 70 Gy and 66 Gy for the primary and the postoperative cases, respectively. The site of recurrence was determined by the diagnostic neuroradiologist to be either within the GTV or the CTV volume by comparison of the treatment planning computed tomography with posttreatment imaging studies.

RESULTS

For the primary definitive cases with a median follow-up of 25 months (range 6 to 78 months), 4 patients failed in the GTV. The 2- and 3-year local freedom from progression (LFFP) rates were 97% and 95%. With a median follow-up of 17 months (range 8 to 56 months), 7 patients failed in the postoperative setting. The 2-year LFFP rate was 83%. For the primary group, the average maximum, mean, and minimum doses delivered were 80 Gy, 74 Gy, 56 Gy to the GTV, and 80 Gy, 69 Gy, 33 Gy to the CTV. An average of only 3% of the GTV and 3% of the CTV received less than 95% of the prescribed dose. For the postoperative group, the average maximum, mean, and minimum doses delivered were 79 Gy, 71 Gy, 37 Gy to the GTV and 79 Gy, 66 Gy, 21 Gy to the CTV. An average of only 6% of the GTV and 6% of the CTV received less than 95% of the prescribed dose.

CONCLUSION

Accurate target volume delineation in IMRT treatment for head-and-neck cancer is essential. Our multidisciplinary approach in target volume definition resulted in few recurrences with excellent LFFP rates and no marginal failures. Higher treatment failure rates were noted in the postoperative setting in which lower doses were prescribed. Potential dose escalation studies may further improve the local control rates in the postoperative setting.

Dose conformation in IMRT for head and neck tumors: which solution to apply?

At Ghent University Hospital, IMRT for head and neck cancer is routinely performed. The desired dose distribution is defined upfront as a range of acceptable doses assigned to each voxel of volumes of interest. It was found important to specify the range of acceptable doses separately to areas of the PTV either in or outside the buildup zone as well as to areas which do or do not intersect with PTV-dose limiting organs at risk (OAR). To avoid high doses at distance from the PTV, the creation of a "surrounding" OAR which is the whole scanned volume minus the PTV was found efficient, especially if inside this OAR, subvolumes were created at increasing distance from the PTV. By specifying inside these subvolumes maximum dose constraints which decreased with distance from the PTV, conformality is secured. The creation of these additional PTV and OAR subvolumes allows comprehensive and unambiguous definition of the range of acceptable doses and thereby avoids user-interactive assignment of weights to the terms of the objective function during optimization. The efficiency of inverse planning is highly improved. Its outcome is predictable, plan evaluation is objective as the plan either does or does not comply with the predefined range of acceptable doses. Accurate reporting of the planned dose distribution is facilitated by description of the dose range to all volumes. The expense of this procedure is modest and lays mostly 1) in the creation of the subvolumes, which can be done semi-automatically by modern image segmentation tools and 2) in the inclusion of constraints to all subvolumes into the objective function.