Risk factors for clinician-reported symptom clusters in patients with advanced head and neck cancer in a phase 3 randomized clinical trial: RTOG 0129.

BACKGROUND: Chemoradiotherapy has become the standard of care for head and neck squamous cell carcinoma; however, those patients often experience multiple treatment-related symptoms or symptom clusters. Two symptom clusters have been identified for this population. Little is known about the risk factors of these symptom clusters. METHODS: Subjects comprised 684 patients who were treated with concurrent chemoradiotherapy in a phase 3 randomized clinical trial. This trial compared standard fractionation radiotherapy to accelerated fractionation radiotherapy. Symptom clusters were evaluated at the end of the first and the second cycle of chemotherapy, and 3 months after the start of radiotherapy. Mixed-effect modeling was used to observe risk factors for symptom clusters. RESULTS: Race and education were independent predictors for the head and neck cluster, whereas sex and history of tobacco use were independent predictors for the gastrointestinal cluster. Primary cancer site was only significant for the head and neck cluster when other factors were not controlled: patients with oropharyngeal cancer had more severe symptoms in the head and neck clusters than did patients with laryngeal cancer. In addition, patients receiving accelerated fractionation radiotherapy experienced more symptoms of radiomucositis, pain, and nausea at 3 months after the start of radiotherapy than those receiving standard fractionation radiotherapy. CONCLUSIONS: Demographic characteristics were more predictive to symptom clusters, whereas clinical characteristics, such as cancer site and treatment arms, were more significant for individual symptoms. Knowing the risk factors will enhance the capability of clinicians to evaluate patients' risk of severe symptom clusters and to personalize management strategies.

Hyperfractionated or accelerated radiotherapy for head and neck cancer.

BACKGROUND: Several trials have studied the role of altered fractionation radiotherapy in head and neck squamous cell carcinoma, but the effect of such treatment on survival is not clear. OBJECTIVES: The aim of this individual patient data (IPD) meta-analysis was to assess whether this type of radiotherapy could improve survival. SEARCH STRATEGY: We searched the Cochrane Ear, Nose and Throat Disorders Group Trials Register; CENTRAL (2010, Issue 3); PubMed; EMBASE; CINAHL; Web of Science; BIOSIS Previews; Cambridge Scientific Abstracts; ISRCTN and additional sources for published and unpublished trials. The date of the most recent search was 8 August 2010. SELECTION CRITERIA: We identified randomised trials comparing conventional radiotherapy with hyperfractionated or accelerated radiotherapy, or both, in patients with non-metastatic head and neck squamous cell carcinomas and grouped trials into three pre-specified treatment categories: hyperfractionated, accelerated and accelerated with total dose reduction. Trials were eligible if they began recruitment after 1969 and ended before 1998. DATA COLLECTION AND ANALYSIS: We obtained updated individual patient data. Overall survival was the main outcome measure. The secondary outcome measures were local or regional control rates (or both), distant control rates and cause-specific mortality. MAIN RESULTS: We included 15 trials with 6515 patients. The median follow up was six years. Tumour sites were mostly oropharynx and larynx; 5221 (74%) patients had stage III-IV disease (UICC 2002). There was a significant survival benefit with altered fractionation radiotherapy, corresponding to an absolute benefit of 3.4% at five years (hazard ratio (HR) 0.92, 95% CI 0.86 to 0.97; P = 0.003). The benefit was significantly higher with hyperfractionated radiotherapy (8% at five years) than with accelerated radiotherapy (2% with accelerated fractionation without total dose reduction and 1.7% with total dose reduction at five years, P = 0.02). There was a benefit in locoregional control in favour of altered fractionation versus conventional radiotherapy (6.4% at five years; P < 0.0001), which was particularly efficient in reducing local failure, whereas the benefit on nodal control was less pronounced. The benefit was significantly higher in the youngest patients (under 50 year old) (HR 0.78, 95% CI 0.65 to 0.94), 0.95 (95% CI 0.83 to 1.09) for 51 to 60 year olds, 0.92 (95% CI 0.81 to 1.06) for 61 to 70 year olds, and 1.08 (95% CI 0.89 to 1.30) for those over 70 years old; test for trends P = 0.007). AUTHORS' CONCLUSIONS: Altered fractionation radiotherapy improves survival in patients with head and neck squamous cell carcinoma. Comparison of the different types of altered radiotherapy suggests that hyperfractionation provides the greatest benefit. An update of this IPD meta-analysis (MARCH 2), which will increase the power of this analysis and allow for other comparisons, is currently in progress.

Surrogate endpoints for overall survival in locally advanced head and neck cancer: meta-analyses of individual patient data.

BACKGROUND: The gold standard endpoint in randomised trials of locally advanced head and neck squamous-cell carcinoma (HNSCC) is overall survival. Our objective was to study whether duration of locoregional control or event-free survival (EFS) could be considered as surrogate endpoints to estimate the effect of radiotherapy and chemotherapy on overall survival. This would allow a reduction in the duration and cost of the development of new treatments. METHODS: Individual patient data from 104 trials (22 744 patients), with 116 treatment-control comparisons, from four meta-analyses on hyperfractionated or accelerated radiotherapy and concomitant, induction, or adjuvant chemotherapy were analysed. Duration of locoregional control was defined as the time from randomisation to the first locoregional event and EFS as the time to any first event (ie, locoregional relapse, distant recurrence, or death). At the individual level, a rank correlation coefficient between the surrogate endpoint and overall survival was used to assess surrogacy; at the trial level, a correlation coefficient R between treatment effects was used. FINDINGS: At the individual level, overall survival was more strongly correlated with EFS (range of correlations 0.82-0.90) than with locoregional control (0.65-0.76). For radiotherapy, treatment effects on both locoregional control and EFS were strongly correlated with those on overall survival (R=0.94 and 0.98, respectively). For chemotherapy, the correlations between treatment effects on EFS and overall survival were stronger than those between locoregional control and overall survival (range of R 0.79-0.93 vs 0.53-0.84, respectively). INTERPRETATION: EFS is a better correlate with overall survival than locoregional control and could be used as a surrogate for overall survival to assess the treatment effect of radiotherapy and chemotherapy in randomised trials of locally advanced HNSCC.

Feasibility of using administrative claims data for cost-effectiveness analysis of a clinical trial.

OBJECTIVE: This study was performed retrospectively to determine if Medicare claims data could be used to evaluate the cost effectiveness, from a payer perspective, of different radiation treatment schedules evaluated in a national clinical trial. METHODS: Medicare costs from all providers and all places of service were obtained from the Centers for Medicare & Medicaid Services for patients treated in the period 1992-1996 on Radiation Therapy Oncology Group 90-03, and combined with data on outcomes from the trial. RESULTS: Of the 1,113 patients entered, Medicare cost data and clinical outcomes were available for 187 patients. Significant differences in tolerance of treatment and outcome were noted between patients with Medicare data included in the study and patients without Medicare data, and non-Medicare patients excluded from it. Ninety-five percent confidence ellipses on the incremental cost-effectiveness scatterplots crossed both axes, indicating non-significant differences in cost effectiveness between radiation treatment schedules. CONCLUSIONS: Claims data permit estimation of cost effectiveness, but Medicare data provide inadequate representation of results applicable to patients from the general population.

Hyperfractionated or accelerated radiotherapy in head and neck cancer: a meta-analysis.

BACKGROUND: Several trials have studied the role of unconventional fractionated radiotherapy in head and neck squamous cell carcinoma, but the effect of such treatment on survival is not clear. The aim of this meta-analysis was to assess whether this type of radiotherapy could improve survival. METHODS: Randomised trials comparing conventional radiotherapy with hyperfractionated or accelerated radiotherapy, or both, in patients with non-metastatic HNSCC were identified and updated individual patient data were obtained. Overall survival was the main endpoint. Trials were grouped in three pre-specified categories: hyperfractionated, accelerated, and accelerated with total dose reduction. FINDINGS: 15 trials with 6515 patients were included. The median follow-up was 6 years. Tumours sites were mostly oropharynx and larynx; 5221 (74%) patients had stage III-IV disease (International Union Against Cancer, 1987). There was a significant survival benefit with altered fractionated radiotherapy, corresponding to an absolute benefit of 3.4% at 5 years (hazard ratio 0.92, 95% CI 0.86-0.97; p=0.003). The benefit was significantly higher with hyperfractionated radiotherapy (8% at 5 years) than with accelerated radiotherapy (2% with accelerated fractionation without total dose reduction and 1.7% with total dose reduction at 5 years, p=0.02). There was a benefit on locoregional control in favour of altered fractionation versus conventional radiotherapy (6.4% at 5 years; p<0.0001), which was particularly efficient in reducing local failure, whereas the benefit on nodal control was less pronounced. The benefit was significantly higher in the youngest patients (hazard ratio 0.78 [0.65-0.94] for under 50 year olds, 0.95 [0.83-1.09] for 51-60 year olds, 0.92 [0.81-1.06] for 61-70 year olds, and 1.08 [0.89-1.30] for over 70 year olds; test for trends p=0.007). INTERPRETATION: Altered fractionated radiotherapy improves survival in patients with head and neck squamous cell carcinoma. Comparison of the different types of altered radiotherapy suggests that hyperfractionation has the greatest benefit.

The impact of concurrent granulocyte macrophage-colony stimulating factor on radiation-induced mucositis in head and neck cancer patients: a double-blind placebo-controlled prospective phase III study by Radiation Therapy Oncology Group 9901.

PURPOSE: Based on early clinical evidence of potential mucosal protection by granulocyte-macrophage colony stimulating factor (GM-CSF), the Radiation Therapy Oncology Group conducted a double-blind, placebo-controlled, randomized study to test the efficacy and safety of GM-CSF in reducing the severity and duration of mucosal injury and pain (mucositis) associated with curative radiotherapy (RT) in head-and-neck cancer patients. METHODS AND MATERIALS: Eligible patients included those with head-and-neck cancer with radiation ports encompassing >50% of oral cavity and/or oropharynx. Standard RT ports were used to cover the primary tumor and regional lymphatics at risk in standard fractionation to 60-70 Gy. Concurrent cisplatin chemotherapy was allowed. Patients were randomized to receive subcutaneous injection of GM-CSF 250 microg/m2 or placebo 3 times a week. Mucosal reaction was assessed during the course of RT using the National Cancer Institute Common Toxicity Criteria and the protocol-specific scoring system. RESULTS: Between October 2000 and September 2002, 130 patients from 36 institutions were accrued. Nine patients (7%) were excluded from the analysis, 3 as a result of drug unavailability. More than 80% of the patients participated in the quality-of-life endpoint of this study. The GM-CSF did not cause any increase in toxicity compared with placebo. There was no statistically significant difference in the average mean mucositis score in the GM-CSF and placebo arms by a t test (p = 0.4006). CONCLUSION: This placebo-controlled, randomized study demonstrated no significant effect of GM-CSF given concurrently compared with placebo in reducing the severity or duration of RT-induced mucositis in patients undergoing definitive RT for head-and-neck cancer.

Targeted therapy against VEGFR and EGFR with ZD6474 enhances the therapeutic efficacy of irradiation in an orthotopic model of human non-small-cell lung cancer.

PURPOSE: Conventional therapies for patients with lung cancer have reached a therapeutic plateau. We therefore evaluated the feasibility of combined vascular endothelial growth factor (VEGF) receptor 2 (VEGFR2) and epidermal growth factor (EGF) receptor (EGFR) targeting with radiation therapy in an orthotopic model that closely recapitulates the clinical presentation of human lung cancer. METHODS AND MATERIALS: Effects of irradiation and/or ZD6474, a small-molecule inhibitor of VEGFR2 and EGFR tyrosine kinases, were studied in vitro for human lung adenocarcinoma cells by using proliferation and clonogenic assays. The feasibility of combining ZD6474 with radiation therapy was then evaluated in an orthotopic model of human lung adenocarcinoma. Lung tumor burden and spread within the thorax were assessed, and tumor and adjacent tissues were analyzed by means of immunohistochemical staining for multiple parameters, including CD31, VEGF, VEGFR2, EGF, EGFR, matrix metalloproteinase-2 and -9, and basic fibroblast growth factor. RESULTS: ZD6474 enhanced the radioresponse of NCI-H441 human lung adenocarcinoma cells by a factor of 1.37 and markedly inhibited sublethal damage repair. In vivo, the combined blockade of VEGFR2 and EGFR by ZD6474 blocked pleural effusion formation and angiogenesis and enhanced the antivascular and antitumor effects of radiation therapy in the orthotopic human lung cancer model and was superior to chemoradiotherapy. CONCLUSIONS: When radiation therapy is combined with VEGFR2 and EGFR blockade, significant enhancement of antiangiogenic, antivascular, and antitumor effects are seen in an orthotopic model of lung cancer. These data provide support for clinical trials of biologically targeted and conventional therapies for human lung cancer.

Parotid gland dose in intensity-modulated radiotherapy for head and neck cancer: is what you plan what you get?

PURPOSE: To quantify the differences between planned and delivered parotid gland and target doses, and to assess the benefits of daily bone alignment for head and neck cancer patients treated with intensity-modulated radiotherapy (IMRT). METHODS AND MATERIALS: Eleven head and neck cancer patients received two CT scans per week with an in-room CT scanner over the course of their radiotherapy. The clinical IMRT plans, designed with 3-mm to 4-mm planning margins, were recalculated on the repeat CT images. The plans were aligned using the actual treatment isocenter marked with radiopaque markers (BB) and bone alignment to the cervical vertebrae to simulate image-guided setup. In-house deformable image registration software was used to map daily dose distributions to the original treatment plan and to calculate a cumulative delivered dose distribution for each patient. RESULTS: Using conventional BB alignment led to increases in the parotid gland mean dose above the planned dose by 5 to 7 Gy in 45% of the patients (median, 3.0 Gy ipsilateral, p = 0.026; median, 1.0 Gy contralateral, p = 0.016). Use of bone alignment led to reductions relative to BB alignment in 91% of patients (median, 2 Gy; range, 0.3-8.3 Gy; 15 of 22 parotids improved). However, the parotid dose from bone alignment was still greater than planned (median, 1.0 Gy, p = 0.007). Neither approach affected tumor dose coverage. CONCLUSIONS: With conventional BB alignment, the parotid gland mean dose was significantly increased above the planned mean dose. Using daily bone alignment reduced the parotid dose compared with BB alignment in almost all patients. A 3- to 4-mm planning margin was adequate for tumor dose coverage.

CpG oligodeoxynucleotides are potent enhancers of radio- and chemoresponses of murine tumors.

BACKGROUND AND PURPOSE: Synthetic oligodeoxynucleotides (ODNs) containing unmethylated cytosine-guanine (CpG) motifs bind to Toll-like receptor 9 (TLR9) and stimulate both innate and adaptive immune reactions and possess anti-tumor activity. We recently reported that CpG ODN 1826 strongly enhances radioresponse of both immunogenic [Milas L, Mason K, Ariga H, et al. CpG oligodeoxynucleotide enhances tumor response to radiation. Cancer Res 2004;64:5074-7] and non-immunogenic [Mason KA, Ariga H, Neal R, et al. Targeting toll-like receptor-9 with CpG oligodeoxynucleotides enhances tumor response to fractionated radiotherapy. Clin Cancer Res 2005;11:361-9] murine tumors. Using two immunogenic murine tumors, a fibrosarcoma (FSa) and a mammary carcinoma (MCa-K), the present study explored whether CpG ODN 1826 also improves the response of murine tumors to the chemotherapeutic agent docetaxel (DOC). MATERIALS AND METHODS: CpG ODN 1826 (100 microg) was given sc three times: when leg tumors were 6mm, when they grew to 8mm and again 1 week later. DOC (33 mg/kg iv) and local tumor radiation (10Gy) were given when tumors were 8mm. Effects of the treatments were assayed by tumor growth delay, defined as days for tumors to grow from 8 to 12 mm in diameter. RESULTS: Treatment with CpG ODN 1826 resulted in strongly enhanced response of FSa tumors to radiation and MCa-K tumors to the chemotherapeutic agent DOC. Enhancement of tumor treatment response was demonstrated by a strong prolongation in the primary tumor treatment endpoint, tumor growth delay. Coincidentally, this treatment also resulted in a higher rate of tumor cure than that observed after tumor radiotherapy or chemotherapy alone. When all three agents were combined the effect was comparable to that of the combination of CpG ODN 1826 with radiation in the case of FSa or of the combination of CpG ODN 1826 with DOC in the case of MCa-K. CONCLUSION: Overall results show that CpG ODN 1826 can markedly improve tumor response to radiation and chemotherapy (DOC), suggesting that CpG ODNs have potential to be beneficial when used singly or in combination with other standard treatment modalities such as taxane chemotherapy, radiotherapy or both.

Rhabdomyolysis following shoulder arthroscopy.

Fluid extravasation is not uncommon after shoulder arthroscopy. We report a case of massive fluid extravasation that resulted in rhabdomyolysis and renal shutdown following routine shoulder arthroscopic surgery. Compartment pressures in the deltoid, supraspinatus, and infraspinatus were normal. Magnetic resonance imaging of the shoulder revealed extensive subcutaneous edema and high-signal changes in the entire deltoid muscle. The patient made an uneventful recovery with adequate supportive treatment and renal dialysis. Repeat imaging studies 3 months later revealed complete restoration to normal of the deltoid muscle. In addition to extensive fluid extravasation in this patient, the use of nonsteroidal anti-inflammatory medication, the development of a transient allergic reaction to a prescribed antibiotic, and the inclusion of epinephrine in the infusion fluid may have collectively contributed to rhabdomyolysis. We recommend that the use of infusion pumps should be limited to the shortest time possible, and that gravity inflow should be used as much as possible. Inflow should preferably occur through the arthroscope itself, rather than through a separate portal cannula, which may dislodge, inadvertently causing infusion of high-pressure fluid into the surrounding tissue.

Association of Human Papillomavirus and p16 Status With Outcomes in the IMCL-9815 Phase III Registration Trial for Patients With Locoregionally Advanced Oropharyngeal Squamous Cell Carcinoma of the Head and Neck Treated With Radiotherapy With or Without Cetuximab.

PURPOSE: We conducted a retrospective evaluation of the IMCL-9815 study to examine the association of human papillomavirus (HPV) and p16 protein expression status with outcomes in patients with oropharyngeal carcinoma (OPC) receiving radiotherapy (RT) plus cetuximab or RT alone. PATIENTS AND METHODS: In the IMCL-9815 study, patients were randomly allocated to receive RT plus weekly cetuximab or RT alone. A subpopulation of patients with p16-evaluable OPC was retrospectively evaluated on the basis of locoregional control (LRC), overall survival (OS), and progression-free survival (PFS). Evaluable samples from patients with p16-positive OPC were also tested for HPV DNA. RESULTS: Tumor p16 status was evaluable in 182 patients with OPC enrolled in the IMCL-9815 study; 41% were p16 positive. When treated with RT alone or RT plus cetuximab, p16-positive patients had a longer OS than p16-negative patients (hazard ratio, 0.40; 95% CI, 0.21 to 0.74 and hazard ratio, 0.16; 95% CI, 0.07 to 0.36, respectively). The addition of cetuximab to RT increased LRC, OS, and PFS in both patients with p16-positive OPC and those with p16-negative disease. Interaction tests for LRC, OS, and PFS did not demonstrate any significant interaction between p16 status and treatment effect (P = .087, .085, and .253, respectively). Similar trends were observed when patients with p16-positive/HPV-positive OPC (n = 49) and those with p16-positive/HPV-negative OPC (n = 14) were compared. CONCLUSION: p16 status was strongly prognostic for patients with OPC. The data suggest that the addition of cetuximab to RT improved clinical outcomes regardless of p16 or HPV status versus RT alone.

Association of human papillomavirus and p16 status with mucositis and dysphagia for head and neck cancer patients treated with radiotherapy with or without cetuximab: Assessment from a phase 3 registration trial.

BACKGROUND: Mucositis and dysphagia are common adverse effects of radiotherapy (RT) treatment of locally advanced squamous cell cancer of the head and neck (LA-SCCHN). Chemotherapy added to RT increases survival rates but causes worse mucositis and dysphagia. The aim of this analysis was to assess the impact of p16 status on mucositis, dysphagia, and feeding tube use in LA-SCCHN among patients treated with RT±cetuximab in the phase 3 IMCL-9815 trial. METHODS: Patients received RT plus weekly cetuximab or RT alone. Subgroup analyses were conducted on patients with p16-positive (n=75) or p16-negative (n=106) oropharyngeal cancer (OPC), as determined by immunohistochemical analysis. The onset and duration of mucositis and dysphagia by treatment arm and p16 status were displayed using Kaplan-Meier curves and the log-rank test. P values for the incidence of mucositis and dysphagia were calculated using the Fisher exact test. Feeding tube use was assessed as the percent of patients reporting use. RESULTS: The baseline characteristics of patients treated with RT±cetuximab were similar in both the p16-positive and p16-negative OPC subgroups. Patients within the p16-positive OPC subgroup had higher Karnofsky scores and were more likely to have stage T1-T3 cancer and be from the United States. Regardless of p16 status, there was no difference in the onset or duration of grade 3/4 mucositis or dysphagia in patients receiving RT plus cetuximab compared with those receiving RT alone. In the overall population, and the p16-positive and p16-negative OPC subpopulations, feeding tube use was not different for patients receiving RT plus cetuximab compared with RT alone. CONCLUSION: Regardless of p16 status, the addition of cetuximab to RT did not alter the incidence, time to onset, severity, or duration of mucositis and dysphagia and did not impact the frequency of feeding tube use.

Maintenance of certification for radiation oncology.

Maintenance of Certification (MOC) recognizes that in addition to medical knowledge, several essential elements involved in delivering quality care must be developed and maintained throughout one's career. The MOC process is designed to facilitate and document professional development of American Board of Radiology (ABR) diplomates in the essential elements of quality care in Radiation Oncology and Radiologic Physics. ABR MOC has been developed in accord with guidelines of the American Board of Medical Specialties. All Radiation Oncology certificates issued since 1995 are 10-year, time-limited certificates; diplomates with time-limited certificates who wish to maintain specialty certification must complete specific requirements of the American Board of Radiology MOC program. Diplomates with lifelong certificates are not required to participate but are strongly encouraged to do so. Maintenance of Certification is based on documentation of participation in the four components of MOC: (1) professional standing, (2) lifelong learning and self-assessment, (3) cognitive expertise, and (4) performance in practice. Through these components, MOC addresses six competencies-medical knowledge, patient care, interpersonal and communication skills, professionalism, practice-based learning and improvement, and systems-based practice. Details of requirements for components 1, 2, and 3 of MOC are outlined along with aspects of the fourth component currently under development.

Inhibition of DNA repair as a mechanism of enhanced radioresponse of head and neck carcinoma cells by a selective cyclooxygenase-2 inhibitor, celecoxib.

PURPOSE: Previously, we reported that inhibitors of cyclooxygenase-2 (COX-2) enzyme enhanced murine and human tumor cell response to radiation in vitro and in vivo. However, the molecular mechanisms mediating the effects of COX-2 inhibitors are not clear. The present study was designed to investigate the ability of celecoxib, a selective COX-2 inhibitor, to sensitize human head-and-neck cancer cell line, HN5, to radiation, and examine its effects on DNA repair, which may be a potential mechanism of radiosensitization. METHODS AND MATERIALS: Cells were assessed for the effect of celecoxib (5-50 microM), by 3-[4,5-dimethylthiozol-2-yl]-2,5-diphenyltetrazolium bromide assay for growth inhibition and by clonogenic cell survival assay for the radiosensitizing effect. Kinase assay and Western analysis were conducted to assess the effect of celecoxib on DNA-dependent protein kinase catalytic subunit (PKcs) and Ku proteins. Electrophoretic mobility shift assays (EMSA) were performed to determine the DNA-binding activity of Ku/DNA-PKcs protein complex and nuclear factor kappa B (NFkappaB). RESULTS: Celecoxib (10 and 50 microM, for 2 days) inhibited the HN5 cell growth and significantly enhanced the cell radiosensitivity in a dose-dependent manner. It also reduced the shoulder region on the radiation-survival curve, suggesting that inhibition of DNA repair processes may have occurred. Western blot analysis demonstrated that celecoxib downregulated the expression of Ku70 protein and inhibited the kinase activity of DNA-PKcs, which are involved in the double-stranded DNA-break repair machinery. By EMSA, it was further shown that celecoxib reduced DNA-binding activity of Ku/DNA-PKcs protein complex. In addition, celecoxib inhibited the constitutively active NFkappaB and the radiation-induced NFkappaB in HN5 cells, suggesting that NFkappaB may play a role in mediating the effects of celecoxib. CONCLUSIONS: Celecoxib strongly enhanced the sensitivity of HN5 carcinoma cells to radiation, which, mechanistically, can be attributed to the inhibition of DNA repair processes in radiation-damaged cells.

Effectiveness of noncoplanar IMRT planning using a parallelized multiresolution beam angle optimization method for paranasal sinus carcinoma.

PURPOSE: To determine the effectiveness of noncoplanar beam configurations and the benefit of plans using fewer but optimally placed beams designed by a parallelized multiple-resolution beam angle optimization (PMBAO) approach. METHODS AND MATERIALS: The PMBAO approach uses a combination of coplanar and noncoplanar beam configurations for intensity-modulated radiation therapy (IMRT) treatment planning of paranasal sinus cancers. A smaller number of beams (e.g. 3) are first used to explore the solution space to determine the best and worst beam directions. The results of this exploration are then used as a starting point for determining an optimum beam orientation configuration with more beams (e.g. 5). This process is parallelized using a message passing interface, which greatly reduces the overall computation time for routine clinical practice. To test this approach, treatment for 10 patients with paranasal sinus cancer was planned using a total of 5 beams from a pool of 46 possible beam angles. The PMBAO treatment plans were also compared with IMRT plans designed using 9 equally spaced coplanar beams, which is the standard approach in our clinic. Plans with these two different beam configurations were compared with respect to dose conformity, dose heterogeneity, dose-volume histograms, and doses to organs at risk (i.e., eyes, optic nerve, optic chiasm, and brain). RESULTS: The noncoplanar beam configuration was superior in most paranasal sinus carcinoma cases. The target dose homogeneity was better using a PMBAO 5-beam configuration. However, the dose conformity using PMBAO was not improved and was case dependent. Compared with the 9-beam configuration, the PMBAO configuration significantly reduced the mean dose to the eyes and optic nerves and the maximum dose to the contralateral optical path (e.g. the contralateral eye and optic nerve). The maximum dose to the ipsilateral eye and optic nerve was also lower using the PMBAO configuration than using the 9-beam configuration, although this difference was not significant. The mean doses to the optic chiasm and brain are marginally lower using the PMBAO configuration than using 9-beam configuration. The maximum doses to the optic chiasm and brain are the same with the PMBAO configuration and the 9-beam configuration. CONCLUSION: Parallelized multiple-resolution beam angle optimization with an optimized noncoplanar beam configuration is an effective and practical approach for IMRT treatment planning. Five-beam treatment plans optimized using the PMBAO are at least equivalent to, and overall better than, the plans using 9 equally spaced coplanar beams.

In vitro enhancement of tumor cell radiosensitivity by a selective inhibitor of cyclooxygenase-2 enzyme: mechanistic considerations.

PURPOSE: Selective cyclooxygenase-2 inhibitors have been reported to enhance the tumor response to radiation in vivo, but the cellular mechanisms underlying the radiosensitizing effect are not understood. In the present study, we investigated several possible mechanisms using a murine sarcoma cell culture system. METHODS AND MATERIALS: Cells derived from a murine sarcoma, designated NFSA, were cultured in vitro and exposed to different (either single or split) doses of radiation with and without a pretreatment of SC-236 (4-[5-(4-chlorophenyl)-3-(trifluoromethyl)-1H-pyrazol-l-yl] benzene sulfonamide), a selective cyclooxygenase-2 (COX-2) inhibitor. The cells were assayed for clonogenic survival to determine the radiosensitizing effect of SC-236. In addition, MTT assay and TUNEL assay were performed to determine the effects of SC-236 and radiation on the cell survival and cell cycle distribution. RNase protection assay was performed on the total RNA extract using probes that encoded for selected cell cycle regulatory proteins, such as cyclins and cyclin-dependent kinases. To monitor the extent of COX-2 activity and its role in radiosensitization, the cellular content of prostaglandin E2, a major metabolite of COX-2 activity on arachidonic acid, was also determined. RESULTS: The cell clonogenic survival assay showed that SC-236 significantly enhanced tumor cell radiosensitivity: 50 microM SC-236 increased it by a factor of 1.51 at the 0.1 cell survival level. Treatment with SC-236 (50 microM, 3 days) removed the "shoulder" region on the radiation survival curve, suggesting that the drug inhibited repair of sublethal radiation damage. The inhibition was confirmed by split-dose experiments where two doses (3 Gy each) of radiation were given 4 h apart. The cells exposed to radiation only repaired the damage by a factor of 1.44, whereas those treated with SC-236 plus radiation repaired it by a factor of 1.1 only. Whereas SC-236 induced apoptosis in these NFSA cells, radiation did not. No further increase in apoptosis was observed when the cells were exposed to both SC-236 and radiation, suggesting that SC-236 did not render tumor cells more susceptible to radiation-induced apoptosis. The RNase protection assay showed that SC-236 (50 microM, 3 days) inhibited the expression of cyclins A and B, as well as cyclin-dependent kinase-1. Inhibition of these cell cycle regulatory elements by SC-236 was associated with the arrest of cells in the radiosensitive G2-M phase (67%), determined by flow cytometry. CONCLUSIONS: SC-236 significantly enhanced radiosensitivity of tumor cells; the magnitude of sensitivity was dependent on the drug's concentration. The likely mechanisms involve accumulation of cells in the radiosensitive G2-M phase of the cell cycle and inhibition of repair from sublethal radiation damage.

Potentiation of tumor response to radiation or chemoradiation by selective cyclooxygenase-2 enzyme inhibitors.

Cyclooxygenase-2 (COX-2) is an enzyme expressed primarily in pathologic states, such as inflammatory disorders and cancer, where it mediates prostaglandin production. Its overexpression is associated with more aggressive biologic tumor behavior and adverse patient outcome. Increasing evidence shows that agents that selectively inhibit COX-2 enhance tumor response to radiation or chemotherapeutic agents. This article gives an overview of some of this evidence. In addition, we describe new results showing that celecoxib, a selective COX-2 inhibitor, enhanced response of A431 human tumor xenografts in nude mice to radiation by an enhancement factor (EF) of 1.43 and to the chemotherapeutic agent docetaxel by an EF of 2.07. Celecoxib also enhanced tumor response when added to the combined docetaxel plus radiation treatment (EF = 2.13). Further experiments showed that selective COX-2 inhibitors enhanced tumor cell sensitivity to ionizing radiation, involving inhibition of cellular repair from radiation damage and cell cycle redistribution as mechanisms for some cell types. The results show that selective COX-2 inhibitors have the potential to improve tumor radiotherapy or radiochemotherapy, and this therapeutic strategy is currently under clinical testing.

Flavopiridol increases therapeutic ratio of radiotherapy by preferentially enhancing tumor radioresponse.

PURPOSE: Recently we reported that inhibition of cyclin-dependent kinases (cdks) by flavopiridol enhanced the radiation response of murine ovarian carcinoma cells in culture. The purpose of this investigation was to extend these studies to in vivo tumor models and test whether flavopiridol increases the therapeutic ratio of radiotherapy. METHODS AND MATERIALS: Three transplantable syngeneic mouse tumors were used: mammary carcinoma (MCa-29), ovarian carcinoma (OCa-I), and a lymphoma (Ly-TH). Tumor treatment endpoints included growth delay, cure, and spontaneous lung metastases (OCa-I tumor). The normal tissue endpoint was survival of jejunal crypt cells quantified microscopically. A range of flavopiridol doses from 0.625 to 5.0 mg/kg were given systemically once or twice daily over 5, 10, or 20 days. Combined therapy flavopiridol treatments were initiated either several days before or shortly after the start of single dose or daily fractionated radiotherapy. RESULTS: The major findings of this study are that all three tumors treated with flavopiridol alone responded by tumor growth delay. Two of the tumors (MCa-29 and Ly-TH) responded in a schedule-dependent manner with larger radiation enhancement factors when flavopiridol treatment was started a few hours after irradiation (radioenhancement factors [EF] Ly-TH = 2.04, EF MCa-29 = 1.50 for single dose irradiation). When combined with fractionated irradiation (2.6 Gy daily for 10 or 20 days), flavopiridol enhanced the response of the MCa-29 tumor by a factor of 1.25-1.46. A fractional radiation dose of 6 Gy in combination with flavopiridol produced a 62.5% cure rate compared with 25% tumor cure for radiation alone. A novel finding of this study was the demonstration of antimetastatic activity of flavopiridol in addition to its effect on the local primary tumor. Both the incidence and absolute number of lung metastasis were reduced when flavopiridol followed surgical removal of the large (10 mm) primary leg tumor. The normal jejunum treated with flavopiridol and radiation responded in a schedule independent manner and the degree of radioenhancement (EF, 1.05-1.06) was much less than for any of the tumors studied. CONCLUSIONS: Therapeutic gain was achieved when flavopiridol treatment was initiated either before or after the start of radiotherapy. Flavopiridol shows promising clinical potential administered alone or in combination with other cytotoxic agents, including both chemotherapy and radiotherapy.