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Biomedical subjects

Paul D Brown

Publications and source records attributed to Paul D Brown.

At least 19 recordsLinked to original sources
PubMed2007

Informed consent in advanced laryngeal cancer.

PURPOSE: This study was designed to evaluate the relationship between the informed consent process and the treatment received by patients with advanced laryngeal cancer. METHODS: The study group was composed of 101 consecutive patients who were eligible for the Department of Veterans Affairs Laryngeal Cancer Study Group and Radiation Therapy Oncology Group/Head and Neck Intergroup (RTOG 91-11) larynx preservation clinical trials and who underwent treatment at the Mayo Clinic during the years 1985 to 2000. Records were reviewed to evaluate the effect that referral to an oncologist, discussion and documentation of treatment alternatives by the surgeon, offering a chance at a larynx conservation surgical procedure, and treatment recommendation made by the surgeon have on the treatment chosen and received by the patient. RESULTS: Discussion of treatment alternatives by the surgeon (p = .0054), referral to an oncologist (p < .0001), offering a chance for a larynx conservation surgical procedure (p = .047), and treatment recommended by the surgeon (p < .0001) were significantly related to the treatment received by the patient. CONCLUSION: The treatment received by a patient with advanced laryngeal cancer is determined by the treatment recommended by the surgeon, referral to an oncologist, discussion of treatment alternatives by the surgeon, and offering a chance for a larynx conservation surgical procedure.

Combined Modality Therapy↗
PubMed2006

Central neurocytoma: management recommendations based on a 35-year experience.

PURPOSE: To examine the outcomes of patients with histologically confirmed central neurocytomas. METHODS AND MATERIALS: The data from 45 patients with central neurocytomas diagnosed between 1971 and 2003 were retrospectively evaluated. Various combinations of surgery, radiotherapy (RT), and chemotherapy had been used for treatment. RESULTS: The median follow-up was 10.0 years. The 10-year overall survival and local control rate was 83% and 60%, respectively. Patients whose tumor had a mitotic index of <3 (per 10 high-power fields) experienced a 10-year survival and local control rate of 89% and 74%, respectively, compared with 57% (p = 0.040) and 46% (p = 0.14) for patients with a tumor mitotic index of > or =3. The 10-year survival and local control rate was 90% and 74% for patients with typical tumors compared with 63% (p = 0.055) and 46% (p = 0.41) for those with atypical tumors. A comparison of gross total resection with subtotal resection showed no significant difference in survival or local control. Postoperative RT improved local control at 10 years (75% with RT vs. 51% without RT, p = 0.045); however, this did not translate into a survival benefit. No 1p19q deletions were found in the 19 tumors tested. CONCLUSION: Although the overall prognosis is quite favorable, one-third of patients experienced tumor recurrence or progression at 10 years, regardless of the extent of the initial resection. Postoperative RT significantly improved local control but not survival, most likely because of the effectiveness of salvage RT. For incompletely resected atypical tumors and/or those with a high mitotic index, consideration should be given to adjuvant RT because of the more aggressive nature.

Adolescent↗
PubMed2006

Detrimental effects of tumor progression on cognitive function of patients with high-grade glioma.

PURPOSE: There is growing recognition that the primary cause of cognitive deficits in adult patients with primary brain tumors is the tumor itself and more significantly, tumor progression. To assess the cognitive performance of high-grade glioma patients, prospectively collected cognitive performance data were analyzed. PATIENTS AND METHODS: We studied 1,244 high-grade brain tumor patients entered onto eight consecutive North Central Cancer Treatment Group treatment trials that used radiation and nitrosourea-based chemotherapy. Imaging studies and Folstein Mini-Mental State Examination (MMSE) scores recorded at baseline, 6, 12, 18, and 24 months were analyzed to assess tumor status and cognitive function over time. RESULTS: The proportion of patients without tumor progression who experienced clinically significant cognitive deterioration compared with baseline was stable at 6, 12, 18, and 24 months (18%, 16%, 14%, and 13%, respectively). In patients without radiographic evidence of progression, clinically significant deterioration in MMSE scores was a strong predictor of a more rapid time to tumor progression and death. At evaluations preceding interval radiographic evidence of progression, there was significant deterioration in MMSE scores for patients who were to experience progression, whereas the scores remained stable for the patients who did not have tumor progression. CONCLUSION: The proportion of high-grade glioma patients with cognitive deterioration over time is stable, most consistent with the constant pressure of tumor progression over time. Although other factors may contribute to cognitive decline, the predominant cause of cognitive decline seems to be subclinical tumor progression that precedes radiographic changes.

Adult↗
PubMed2006

The relationship between six-month progression-free survival and 12-month overall survival end points for phase II trials in patients with glioblastoma multiforme.

Common end points for phase II trials in patients with glioblastoma multiforme (GBM) are six-month progression-free survival (PFS6) and 12-month overall survival (OS12). OS12 can be accurately measured but may be confounded with subsequent therapies upon progression, whereas the converse is true for PFS6. Our goal was to assess the relationship between these end points separately for phase II trials in patients with newly diagnosed GBM and patients with recurrent GBM. Data were pooled from 11 North Central Cancer Treatment Group trials for patients with newly diagnosed GBM (n = 1348). All patients received radiotherapy and pharmaceutical therapy (before, during, or after radiotherapy). Data were pooled from 16 trials that used various pharmaceuticals in treating patients for recurrent GBM (n = 345). All trial regimens were declared nonefficacious by predefined criteria. Overall per-patient concordance was estimated with a kappa statistic. The relationship between OS12 and PFS6 across study arms was assessed by weighted linear regression and Pearson's correlation. Simulation was used to determine the agreement of study outcomes when using PFS6 versus OS12 end points. Cox models with progression status as a time-dependent variable and Kaplan-Meier estimators were used to ascertain the association between progression-free survival status and overall survival. At present, 97% of the patients with newly diagnosed GBM and 95% of those with recurrent GBM have died. The PFS6 and OS12 were 43% and 41%, respectively, for patients with newly diagnosed disease and 9% and 14% for patients with recurrent disease. There was only moderate concordance between the end points on both the patient level and the study level. For the simulation studies, we established phase II efficacy criteria for each end point by using the pooled estimates of OS12 (PFS6) as historical controls. The study decisions made using PFS6 and OS12 were in agreement 88% and 90% of the time for the trials of newly diagnosed and recurrent disease, respectively. Finally, there was a strong association between progression-free survival status and overall survival. PFS6 seems to be a reasonable end point for phase II trials in patients with recurrent glioblastoma.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2006

Stereotactic radiosurgery for brainstem metastases: Survival, tumor control, and patient outcomes.

PURPOSE: Patients with brainstem metastases have limited treatment options. In this study, we reviewed outcomes after stereotactic radiosurgery (SRS) in the management of patients with brainstem metastases. METHODS AND MATERIALS: Records were reviewed of 22 consecutive patients presenting with brainstem metastases who underwent SRS. The most frequent primary malignancy was the lung (n = 11), followed by breast (n = 3) and kidney (n = 2). Three patients (14%) also underwent whole-brain radiation therapy (WBRT). The median tumor volume was 0.9 mL (range, 0.1-3.3 mL); the median tumor margin dose was 16 Gy (range, 14-23 Gy). RESULTS: Median survival time after SRS was 8.5 months. Although local tumor control was achieved in all patients with imaging follow-up (n = 19), 5 patients died from development and progression of new brain metastases. Two patients (9%) had symptom improvement after SRS, whereas 1 patient (5%) developed a new hemiparesis after SRS. CONCLUSIONS: Radiosurgery is safe and provides a high local tumor control rate for patients with small brainstem metastases. Patients with limited systemic disease and good performance status should be strongly considered for SRS.

Adult↗
PubMed2006

Acute impairment of insulin signalling by dexamethasone in primary cultured rat skeletal myocytes.

In this study, we examined the cellular content of the insulin receptor substrate (IRS)-1, the levels of phosphorylated tyrosine (pY) and serine (pS) residues in IRS-1, and the glucose transporters GLUT-1 and GLUT-4 in primary cultured rat skeletal myocytes treated with the glucocorticoid, dexamethasone. Dexamethasone markedly increased basal and insulin-stimulated IRS-1 content 4 to 5-fold (p < 0.01). A similar level of increase was observed for IRS-1 pY content. However, dexamethasone treatment had no effect on IRS-1 pS content. Further, dexamethasone reduced the cellular content of GLUT-1 when insulin and glucose were absent (p < 0.05), but did not significantly affect the expression of GLUT-4 in the presence of insulin (p > 0.05). We conclude that dexamethasone treatment impairs insulin signalling by a mechanism independent of serine-phosphorylation-mediated IRS-1 depletion, or of impairment of GLUT-1 expression. Instead, dexamethasone-induced insulin resistance may be mediated via reduced cellular content of IRS-1 accompanied by parallel reduction in tyrosine phosphorylation in IRS-1.

Animals↗
PubMed2006

A t(1;19)(q10;p10) mediates the combined deletions of 1p and 19q and predicts a better prognosis of patients with oligodendroglioma.

Combined deletion of chromosomes 1p and 19q is associated with improved prognosis and responsiveness to therapy in patients with anaplastic oligodendroglioma. The deletions usually involve whole chromosome arms, suggesting a t(1;19)(q10;p10). Using stem cell medium, we cultured a few tumors. Paraffin-embedded tissue was obtained from 21 Mayo Clinic patients and 98 patients enrolled in 2 North Central Cancer Treatment Group (NCCTG) low-grade glioma trials. Interphase fusion of CEP1 and 19p12 probes detected the t(1;19). 1p/19q deletions were evaluated by fluorescence in situ hybridization. Upon culture, one oligodendroglioma contained an unbalanced 45,XX,t(1;19)(q10;p10). CEP1/19p12 fusion was observed in all metaphases and 74% of interphase nuclei. Among Mayo Clinic oligodendrogliomas, the prevalence of fusion was 81%. Among NCCTG patients, CEP1/19p12 fusion prevalence was 55%, 47%, and 0% among the oligodendrogliomas, mixed oligoastrocytomas, and astrocytomas, respectively. Ninety-one percent of NCCTG gliomas with 1p/19q deletion and 12% without 1p/19q deletion had CEP1/19p12 fusion (P < 0.001, chi(2) test). The median overall survival (OS) for all patients was 8.1 years without fusion and 11.9 years with fusion (P = 0.003). The median OS for patients with low-grade oligodendroglioma was 9.1 years without fusion and 13.0 years with fusion (P = 0.01). Similar significant median OS differences were observed for patients with combined 1p/19q deletions. The absence of alterations was associated with a significantly shorter OS for patients who received higher doses of radiotherapy. Our results strongly suggest that a t(1;19)(q10;p10) mediates the combined 1p/19q deletion in human gliomas. Like combined 1p/19q deletion, the 1;19 translocation is associated with superior OS and progression-free survival in low-grade glioma patients.

Adolescent↗
PubMed2006

Multiple sclerosis, brain radiotherapy, and risk of neurotoxicity: the Mayo Clinic experience.

PURPOSE: The aim of this study was a retrospective assessment of neurotoxicity in patients with multiple sclerosis (MS) receiving external beam radiotherapy (EBRT) to the brain. METHODS AND MATERIALS: We studied 15 consecutively treated patients with MS who received brain EBRT. Neurologic toxicity was assessed with the Common Toxicity Criteria v.3.0. RESULTS: Median follow-up for the 5 living patients was 6.0 years (range, 3.3-27.4 years). No exacerbation of MS occurred in any patient during EBRT. Five patients had Grade 4 neurologic toxicity and 1 had possible Grade 5 toxicity. Kaplan-Meier estimated risk of neurotoxicity greater than Grade 4 at 5 years was 57% (95% confidence interval, 27%-82%). Toxicity occurred at 37.5 to 54.0 Gy at a median of 1.0 year (range, 0.2-4.3 years) after EBRT. Univariate analysis showed an association between opposed-field irradiation of the temporal lobes, central white matter, and brainstem and increased risk of neurotoxicity (p < 0.04). Three of 6 cases of toxicity occurred in patients treated before 1986. CONCLUSIONS: External beam radiotherapy of the brain in patients with MS may be associated with an increased risk of neurotoxicity compared with patients without demyelinating illnesses. However, this risk is associated with treatment techniques that may not be comparable to modern, conformal radiotherapy.

Adolescent↗
PubMed2006

Antimicrobial resistance in clinical isolates of Staphylococcus aureus from hospital and community sources in southern Jamaica.

OBJECTIVES: In this study, we assessed the antimicrobial susceptibility patterns and prevalence of methicillin resistance among Staphylococcus aureus isolates from hospital and community sources in southern Jamaica. METHODS: Eighty isolates of S. aureus obtained from hospital and community-based patients with staphylococcal infections were collected, and antimicrobial susceptibilities were determined by disk diffusion. RESULTS: While all specimens yielded isolates, multidrug-resistant isolates were obtained only from urine, high vaginal swab, abscess aspirate, and catheter tip samples. The overall prevalence of methicillin-resistant S. aureus (MRSA) was 23%. The proportions of MRSA isolated from hospital sources (18/39) and community sources were 46% and 0%, respectively (p<0.05). The pattern of antibiotic susceptibility of S. aureus differed significantly between MRSA and methicillin-susceptible (MSSA) isolates. For MRSA isolates, multiple-drug resistance was common and only few antibiotics were active against these isolates. However, no MRSA was resistant to vancomycin. Except for penicillin and to some extent co-trimoxazole (trimethoprim-sulfamethoxazole), most MSSA isolates were susceptible to nearly all antimicrobial agents used in this study. CONCLUSIONS: This is the first report of MRSA from this region of Jamaica. Because methicillin resistance is associated with multiple-drug resistance in S. aureus, it is imperative that surveillance initiatives be focused on both the hospital and community in order to monitor and limit the spread of this organism.

Anti-Bacterial Agents↗
PubMed2006

Nitric oxide agents impair insulin-mediated signal transduction in rat skeletal muscle.

BACKGROUND: Evidence demonstrates that exogenously administered nitric oxide (NO) can induce insulin resistance in skeletal muscle. We have investigated the modulatory effects of two NO donors, S-nitroso-N-acetyl-D, L-penicillamine (SNAP) and S-nitrosoglutathione (GSNO) on the early events in insulin signaling in rat skeletal myocytes. RESULTS: Skeletal muscle cells from 6-8 week old Sprague-Dawley rats were treated with SNAP or GSNO (25 ng/ml) in the presence or absence of glucose (25 mM) and insulin (100 nM). Cellular insulin receptor-beta levels and tyrosine phosphorylation in IRS-1 were significantly reduced, while serine phosphorylation in IRS-1 was significantly increased in these cells, when compared to the insulin-stimulated control. Reversal to near normal levels was achieved using the NO scavenger, 2-(4-carboxyphenyl)-4, 4, 5, 5-tetramethylimidazoline-1-oxyl 3-oxide (carboxy-PTIO). CONCLUSION: These data suggest that NO is a potent modulator of insulin-mediated signal transduction and may play a significant role in the pathogenesis of type 2 diabetes mellitus.

Animals↗
PubMed2006

Long-term results of irradiation for paraganglioma.

PURPOSE: The management of paragangliomas is controversial. Observation, surgery, external-beam radiotherapy (EBRT), and stereotactic radiosurgery (SRS) may, alone or in combination, be appropriate, depending on the size and extent of the tumor, previous treatment, and patient age, general health, and neurologic condition. Few data exist regarding long-term tumor control and late effects after EBRT or SRS. METHODS AND MATERIALS: We performed a retrospective review of all patients treated with EBRT or SRS for paraganglioma at our institution between 1967 and 1994. The endpoints of the study were tumor control and late complications. RESULTS: The 33 patients in this study had a median follow-up of 13 years (range, 4 months to 36 years). The 10-year tumor control rate was 92% (95% confidence interval, 75-98%). At the last follow-up visit, no patient had developed a radiation-induced malignancy. CONCLUSION: External-beam RT and SRS are safe and effective for enlarging and/or symptomatic paragangliomas. The risk of developing a delayed radiation-induced malignancy after EBRT or SRS is low. This risk must be weighed against the significant immediate and permanent risk of cranial nerve deficits if the tumor is untreated or is surgically resected. This risk must also be weighed against the immediate but low risk of surgical mortality.

Adolescent↗
PubMed2006

Phase I trial of erlotinib with radiation therapy in patients with glioblastoma multiforme: results of North Central Cancer Treatment Group protocol N0177.

PURPOSE: To evaluate the toxicity and maximum tolerated dose (MTD) of erlotinib plus radiation therapy (RT) in patients with glioblastoma multiforme (GBM) in a multicenter phase I trial. METHODS AND MATERIALS: Patients were stratified on the basis of the use of enzyme-inducing anticonvulsants (EIACs). After resection or biopsy, patients were treated with erlotinib for 1 week before concurrent erlotinib and 6 weeks (60 Gy) of RT and maintained on erlotinib until progression. The erlotinib dose was escalated in cohorts of 3 starting at 100 mg/day. RESULTS: Twenty patients were enrolled and 19 were evaluable for the MTD and efficacy endpoints. Of these patients, 14 were males and 5 were females, with a median age of 54 years. Seven had undergone biopsy only, 5 had subtotal resections, and 7 had gross total resections. The highest dose level was 150 mg/day erlotinib for patients not on EIACs (Group 1) and 200 mg/day for patients on EIACs (Group 2). MTD was not reached in either group. In Group 1 at 100 mg (n=6) and at 150 mg (n=4), only 1 dose-limiting toxicity (DLT) occurred (stomatitis at 100 mg). No DLTs have occurred in Group 2 at 100 mg (n=3), 150 mg (n=3), and 200 mg (n=3). With a median follow-up of 52 weeks, progression was documented in 16 patients and 13 deaths occurred. Median time to progression was 26 weeks, and median survival was 55 weeks. CONCLUSION: Toxicity is acceptable at the current doses of erlotinib plus RT. The study was modified to include concurrent and adjuvant temozolomide, and accrual is in progress.

Adult↗
PubMed2006

Use of an orthotopic xenograft model for assessing the effect of epidermal growth factor receptor amplification on glioblastoma radiation response.

PURPOSE: The influence of epidermal growth factor receptor (EGFR) amplification on glioblastoma patient prognosis following definitive radiotherapy has been extensively investigated in clinical studies, and yet the relationship between EGFR status and radiation response remains unclear. The intent of the current study was to address this relationship using several EGFR-amplified glioblastoma xenografts in an orthotopic athymic mouse model. EXPERIMENTAL DESIGN: We examined the effect of radiation on the survival of nude mice with intracranial xenografts derived from 13 distinct patient tumors, 7 of which have amplified EGFR. Mice with established intracranial tumors were randomized to sham treatment or 12-Gy radiation in six fractions delivered over 12 days. RESULTS: For six of the xenografts, radiation of mice with intracranial tumor significantly extended survival, and four of these xenografts had EGFR amplification. For seven other xenografts, radiation treatment did not significantly extend survival, and three of these, including GBM12, had EGFR amplification. Similar to EGFR, the tumor genetic status of p53 or PTEN did not show preferential association with radiation-sensitive or radiation-resistant xenografts whereas hyperphosphorylation of Akt on Ser(473) was associated with increased radioresistance. To specifically investigate whether inhibition of EGFR kinase activity influences radiation response, we examined combined radiation and EGFR inhibitor treatment in mice with intracranial GBM12. The combination of oral erlotinib administered concurrently with radiation resulted only in additive survival benefit relative to either agent alone. CONCLUSIONS: Our results indicate that EGFR amplification, as a biomarker, is not singularly predictive of glioblastoma response to radiation therapy, nor does the inhibition of EGFR enhance the intrinsic radiation responsiveness of glioblastoma tumors. However, efficacious EGFR inhibitor and radiation monotherapy regimens can be used in combination to achieve additive antitumor effect against a subset of glioblastoma.

Adult↗
PubMed2006

Role and relevance of neurocognitive assessment in clinical trials of patients with CNS tumors.

The inclusion of neurocognitive end points in clinical trials of patients with CNS tumors is increasing. Neurocognitive end points are used to understand what cognitive problems exist before treatment to establish a baseline by which the effect of treatment is judged, and to determine whether different treatment regimens improve neurocognitive function due to better tumor control, slow expected neurocognitive deterioration due to the tumor, or have more or less short- and long-term neurotoxicity. However, the use of neurocognitive end points in clinical trials for patients with CNS tumors is in its infancy, so that long-term outcomes are difficult to predict and the ability to determine the effects of different agents and treatment approaches is scant. Including this aspect of patient evaluation in addition to survival and time to tumor progression will yield better risk-versus-benefit assessments as well as provide a basis for improving interventions.

Central Nervous System Neoplasms↗
PubMed2006

Exogenous nitric oxide inhibits IRS-1 expression in rat hepatocytes and skeletal myocytes.

Accumulative evidence has supported the role of nitric oxide (NO) in a variety of normal physiological functions as well as many pathological conditions. In this study, we examined the possible diabetogenicity of NO by measuring the expression of the insulin receptor substrate (IRS)-1 in rat hepatocytes and skeletal myocytes. IRS-1 is important in the insulin-mediated signal transduction pathway in both liver and skeletal muscle. Exogenous NO donated by S-nitroso-N-acetylpenicillamine (SNAP) and S-nitrosoglutathione (GSNO) resulted in significant reduction in levels of IRS-1 in both cells, when compared to the insulin-stimulated control (p<0.001). Reversal to near normal levels was achieved using the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (carboxy-PTIO). SNAP was the more potent drug, and the skeletal myocytes were the more sensitive cells to the inhibitory effects of NO released from the drugs. These results provide further evidence that exogenous NO is a potent modulator of insulin-mediated signal transduction and may play a significant role in the pathogenesis of type 2 diabetes mellitus.

Animals↗
PubMed2006

Antimicrobial resistance of Escherichia coli isolates from broiler chickens and humans.

BACKGROUND: Antimicrobial usage is considered the most important factor promoting the emergence, selection and dissemination of antimicrobial-resistant microorganisms in both veterinary and human medicine. The aim of this study was to investigate the prevalence and genetic basis of tetracycline resistance in faecal Escherichia coli isolates from healthy broiler chickens and compare these data with isolates obtained from hospitalized patients in Jamaica. RESULTS: Eighty-two E. coli strains isolated from faecal samples of broiler chickens and urine and wound specimens of hospitalized patients were analyzed by agar disc diffusion to determine their susceptibility patterns to 11 antimicrobial agents. Tetracycline resistance determinants were investigated by plasmid profiling, transformations, and amplification of plasmid-borne resistance genes. Tetracycline resistance occurred at a frequency of 82.4% in avian isolates compared to 43.8% in human isolates. In addition, among avian isolates there was a trend towards higher resistance frequencies to kanamycin and nalidixic acid (p < 0.05), while a greater percentage of human isolates were resistant to chloramphenicol and gentamicin (p < 0.05). Multiple drug resistance was found in isolates from both sources and was usually associated with tetracycline resistance. Tetracycline-resistant isolates from both avian and human sources contained one or several plasmids, which were transmissible by transformation of chemically-competent E. coli. Tetracycline resistance was mediated by efflux genes tetB and/or tetD. CONCLUSION: The present study highlights the prevalence of multiple drug resistant E. coli among healthy broiler chickens in Jamaica, possibly associated with expression of tetracycline resistance. While there did not appear to be a common source for multiple drug resistance in the strains from avian or human origin, the genes encoding resistance are similar. These results suggest that genes are disseminated in the environment and warrant further investigation of the possibility for avian sources acting as reservoirs for tetracycline resistance.

Animals↗
PubMed2006

Organ preservation for advanced laryngeal carcinoma.

BACKGROUND: Inclusion of patients with mobile vocal cords on larynx preservation trials may lead to overstatement of larynx preservation (LPR) and survival (OS) rates. METHODS: This is a retrospective review of patients at our institution who would have been eligible for the Department of Veterans Affairs Laryngeal Cancer Study Group (VA) and Radiation Therapy Oncology Group/Head and Neck Intergroup (RTOG 91-11) clinical trials. No laryngeal conservation procedure could be performed in patients with mobile vocal cords. RESULTS: One hundred one patients at our institution would have been eligible for the VA trial. The 2-year OS was 76% for total laryngectomy and 90% for radiotherapy patients (p = .28) compared with 68% reported for the VA trial. Seventy-three patients at our institution would have been eligible for the RTOG 91-11 trial. The 5-year OS was 52% for total laryngectomy and 63% for radiotherapy patients (p = .18) compared with 55% reported for the RTOG 91-11 trial. Radiotherapy patients had an LPR of 80% (VA trial) and 86% (RTOG 91-11 trial). CONCLUSION: It is unlikely that inclusion of patients with mobile vocal cords had a significant impact on OS or LPR for the VA and RTOG 91-11 larynx preservation trials.

Carcinoma, Squamous Cell↗