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Biomedical subjects

R R Weichselbaum

Publications and source records attributed to R R Weichselbaum.

335 records · Page 19Linked to original sources
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Accurate three-dimensional registration of CT, PET, and/or MR images of the brain.

A surface matching technique has been developed to register multiple imaging scans of the brain in three dimensions, with accuracy on the order of the image pixel sizes. Anatomic information visualized in X-ray CT and magnetic resonance images may be integrated with each other and with functional information from positron emission tomography. Anatomical structures and other volumes of interest may be mapped from one scan to another, and corresponding sections through multiple scans may be directly compared. This capability provides a novel quantitative method to address the fundamental problem of relating structure to function in the brain. Applications include basic and clinical problems in the neurosciences and delivery and assessment of brain tumor therapy.

Brain↗
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Role of chemotherapy in the multidisciplinary approach to advanced head and neck cancer: potentials and problems.

Chemotherapy as initial treatment for advanced squamous carcinoma has received much recent attention. Despite sparse experimental data supporting its usefulness, such chemotherapy is now used for a variety of advanced malignancies. This experience is conceptually reviewed, with special emphasis on squamous carcinoma of the head and neck. Factors which influence treatment results, such as drug dosage, radiation treatment planning, and surgical resection, will require careful analysis in the evolution of the multidisciplinary approach to advanced head and neck cancer.

Antineoplastic Agents↗
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Chemical modulation of the hypoxic fraction in the treatment of head and neck cancer.

Treatment of large squamous carcinomas of the head and neck often requires intensive of multidisciplinary treatment. Despite such aggressive measures, local recurrence is common. Possible reasons for such local failure are numerous. Hypoxic but viable tumor cells may be one means of resistance to radiotherapy and chemotherapy. If surgical removal cannot eliminate these cells, tumor regrowth may occur. Modulation of the hypoxic fraction is one means of potentially altering resistance to radiotherapy. Misonidazole, a radiosensitizer, has been thought to increase free radical formation in hypoxic cells in vitro thus increasing the radiosensitivity. This observation is discussed with reference to advanced head and neck cancer.

Animals↗
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Multimodality therapy in advanced paranasal sinus carcinoma: superior long-term results.

PURPOSE: This study was conducted to determine the efficacy of multimodality treatment for stage III and IV, locoregionally advanced paranasal sinus carcinoma. PATIENTS AND METHODS: A subgroup analysis of 19 consecutive patients with stage III or IV paranasal sinus carcinoma treated with multimodality therapy from head and neck cancer protocols between 1984 and 1996 were analyzed for outcome. Sixteen patients received induction chemotherapy consisting of three cycles of cisplatin and 5-fluorouracil, followed by traditional resection (14 patients) or surgical debulking (two patients). Surgery was followed by concomitant chemoradiotherapy with hydroxyurea and 5-fluorouracil in a week-on, week-off sequence in 15 patients. One patient received standard radiation therapy. An additional three patients were treated with a sequence of surgical resection followed by concomitant chemoradiotherapy. The median total dose to the primary tumor was 60 Gy (range, 45-74 Gy). RESULTS: The overall survival at 5 and 10 years by lifetable analysis was 72.7% and 53.9%, respectively, and the disease-free survival at both 5 and 10 years was 66.6%. Local control was 76.1% at both 5 and 10 years. In the subgroup of patients treated with induction chemotherapy, 87% (14/16) achieved a clinical response. A complete response was confirmed at the time of surgery in five patients, whereas 11 patients had residual disease in the surgical specimen. Regional and distant failures were unusual (one patient each), with a 10-year regional control rate of 93% and a distant control rate of 95.5%. Serious, nonreversible long-term complications included two cases of unilateral blindness, one cataract, and one case of ototoxicity. DISCUSSION: An excellent long-term outcome with respect to local control, overall survival, and disease-free survival is achieved in locoregionally advanced paranasal sinus cancer treated with induction chemotherapy, surgery, and concomitant chemoradiotherapy. The 15 patients treated with this regimen had 10-year overall survival, disease-free survival, and local control rates of 56%, 73%, and 79%, respectively. These results are encouraging and are superior to the 40% survival achieved with surgery and radiation therapy. Further investigation of this regimen is warranted.

Adult↗
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Antitumor interaction of short-course endostatin and ionizing radiation.

PURPOSE: The purpose of this study was to evaluate whether endostatin, an antiangiogenic cleavage fragment of collagen XVIII, enhances the antitumor effects of ionizing radiation (IR). Endostatin was injected to coincide with fractionated radiotherapy. METHODS: Xenografts of radioresistant SQ-20B tumor cells were established in athymic nude mice. Lewis lung carcinoma cells were injected into C57BI/6 mice. Mice bearing SQ-20B xenografts were injected intraperitoneally with 2.5 mg/kg/day of murine recombinant endostatin 5 times per week for 2 weeks 3 hours before IR treatment (50 Gy total dose). Mice bearing Lewis lung carcinoma tumors were injected intraperitoneally with endostatin (2.5 mg/kg/day) four times; the first injection was given 24 hours before the first IR dose (15 Gy) and then 3 hours before IR (15 Gy/day) for 3 consecutive days. Microvascular density was assessed on tumor tissue sections by use of CD31 immunohistochemistry and light microscopy. Endothelial cell survival analyses were employed to evaluate endostatin effects on human aortic endothelial cells and human umbilical vein endothelial cells. Endothelial cell apoptosis was examined by use of FACS analysis and DAPI microscopy. RESULTS: In SQ-20B xenografts, combined treatment with endostatin and IR produced tumor growth inhibition that was most pronounced at the nadir of regression (day 21). By day 35, tumors receiving combined treatment with endostatin and IR were 47% smaller than tumors treated with endostatin alone. Interactive cytotoxic treatment effects between endostatin and IR were also demonstrated in mice bearing Lewis lung carcinoma tumors. Significant tumor growth inhibition was observed in the endostatin/IR group at days 11 and 13 compared with IR alone. Histologic analyses demonstrated a reduction in microvascular density after combined treatment with endostatin and IR compared with endostatin treatment alone. Survival analyses confirmed interactive cytotoxicity between endostatin and IR in both human aortic endothelial cells and human umbilical vein endothelial cells but not in SQ-20B tumor cells. Combined treatment with endostatin and IR produced an increase in cow pulmonary artery endothelial apoptosis compared with either treatment alone. DISCUSSION: The tumor regression observed after combined treatment with endostatin and IR suggests additive antitumor effects in both human and murine tumors. Importantly, the concentrations of endostatin employed produced little tumor regression when endostatin was employed as a single agent. The results from the clonogenic and apoptosis assays support the hypothesis that the endothelial compartment is the target for the endostatin/IR interaction.

Animals↗
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Induction chemotherapy followed by concomitant chemoradiotherapy in the treatment of locoregionally advanced oropharyngeal cancer.

PURPOSE: Locoregionally advanced oropharyngeal cancer has been conventionally treated with either surgery and adjuvant radiotherapy or radiotherapy alone, and clinical and functional outcomes have been poor. Chemoradiotherapy has been demonstrated to improve functional outcome and disease control over conventional treatment in recent randomized head and neck trials. Herein, we report overall survival, progression-free survival, and patterns of failure in locoregionally advanced oropharyngeal cancer treated with induction chemotherapy with or without conservative surgery followed by concomitant chemoradiation. MATERIALS AND METHODS: Three cycles of induction chemotherapy consisting of cisplatin, 5-fluorouracil, leucovorin, and interferon alpha-2b (PFL-IFN) were followed by conservative, organ-sparing surgery for residual disease. All patients then proceeded to concomitant chemoradiation consisting of seven or eight cycles of 5-fluorouracil, hydroxyurea, and a total radiotherapy dose of roughly 7,000 cGy. RESULTS: Sixty-one patients with predominantly stage IV disease were treated. Clinical complete response was observed in 65% of patients after induction therapy. The median follow-up was 68.0 months for survivors and 39.0 months for all patients. At 5 years, overall survival is 51%, progression-free survival is 64%, locoregional control is 70%, and distant control is 89%. Locoregional recurrence accounted for 80% of all initial failures. Only five radical surgeries (none were total glossectomy) were performed for initial disease control. Treatment-related toxicity accounted for four deaths. CONCLUSION: PFL-IFN given with 5-fluorouracil, hydroxyurea, and radiotherapy produces a high rate of cures with organ preservation in a disease group that has traditionally fared poorly. Local and distant disease control and survival rates exceed those observed with more standard treatment approaches involving surgery and radiotherapy. Further investigation into chemoradiotherapy as a curative modality for this disease is warranted.

Adult↗
PubMedDate not supplied

Racial differences in prostate-specific antigen levels in patients with local-regional prostate cancer.

Prostate cancer is a significant health problem for blacks. The incidence and mortality rates are higher in blacks than in whites; blacks often present with a higher stage. Prostate-specific antigen (PSA) is a very useful serum marker in prostate cancer. We analyzed data from a cohort of 161 patients to determine whether there were any racial differences in PSA levels prior to treatment in local-regional prostate cancer. The immunoradiometric method was used to determine the PSA values. The mean PSA levels were significantly higher in blacks than in whites (P = 0.022), and the difference remained significant in multivariate analysis after adjusting for stage and grade (P = 0.020). However, when analyzed further, the difference was statistically significant in one hospital (P = 0.001) and not in another (P = 0.493). Thus, our results are not unequivocal, but our data do suggest that racial differences in PSA levels not accounted for by tumor stage or grade may exist. Assuming that the data truly reflect a racial difference, the cause(s) of this difference remains to be determined. It may exist because, within each clinical stage, blacks are presenting with a higher tumor cell burden, or it may be indicative of more aggressive biological behavior. The possibility that racial differences are due to socioeconomic factors was considered by estimating median income level from zip code of residence; although a correlation between socioeconomic status and PSA level was found, racial differences remained borderline significant (P = 0.055) after adjusting for income level (in addition to stage and grade).

Black or African American↗
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Phase I dose-escalation study of tumor necrosis factor-alpha and concomitant radiation therapy.

PURPOSE: Tumor necrosis factor-alpha enhances x-ray killing of human tumor cells in vitro and enhances tumor control when combined with radiation in animal tumor models. To determine the toxicity and maximal tolerated dose of tumor necrosis factor-alpha given daily during radiotherapy, we conducted a phase I dose-escalation study combining tumor necrosis factor-alpha and radiation. PATIENTS AND METHODS: Thirty-one patients, including 14 patients with locally advanced primary tumors and 17 patients with metastatic sites, were entered into this study. Recombinant human tumor necrosis factor-alpha was administered intravenously at doses ranging from 10 microg/m2 to 150 microg/m2 4 hours prior to each radiation therapy session, which was given on consecutive days for a minimum of 2 weeks. Radiation was prescribed to localized fields, with dose fractions ranging from 150 to 300 cGy/day for palliation or control of locally advanced tumors. RESULTS: Major toxicity requiring withdrawal from the study was independent of tumor necrosis factor-alpha dose and occurred in seven patients. Symptoms included angina in two patients, and hypotension, respiratory distress, atrial fibrillation, allergic reaction, and progressive leukopenia in one patient each. A tumor necrosis factor-alpha dose of 150 microg/m2 was the maximum dose administered. No single dose-limiting toxicity was observed and a maximal tolerated dose could not be defined. There was no obvious increase in in-field toxicity. Response to treatment was assessed in 20 patients. Complete regression within the irradiated field was achieved in four patients, partial regression in four, and a minimal response in four. A trend toward a greater response rate at higher doses of tumor necrosis factor-alpha was observed. CONCLUSIONS: The maximal tolerated dose of tumor necrosis factor-alpha when given with radiotherapy is at least 150 microg/m2 and a dose-limiting toxicity was not observed. Future studies will show whether responses to treatment are increased over those expected with radiation alone. Tumor localization of tumor necrosis factor-alpha by gene therapy combined with radiation therapy may eliminate the systemic toxicity we observed.

Adult↗
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Tumor necrosis factor-alpha-based gene therapy enhances radiation cytotoxicity in human prostate cancer.

The purpose of the present study was to determine the therapeutic potential of combining radiotherapy with tumor necrosis factor (TNF)-alpha-based gene therapy in the human prostate cancer PC-3 xenograft. PC-3 cells are highly resistant to TNF-alpha-induced cytotoxicity in vitro. A modest enhancement of radiation killing was observed with the addition of TNF-alpha in clonogenic survival assays. Combined treatment with Ad.Egr-TNF, a replication-deficient adenovirus modified to express TNF-alpha following the exposure of infected cells to ionizing radiation (40 Gy administered at 5 Gy per fraction) in vivo, resulted in increased tumor control, as defined by a reduction of tumor volume, when compared with treatment with Ad.Egr-TNF alone or with radiation alone (P < .03). The improvement in tumor control was achieved without increasing acute normal tissue damage when compared with tissue injury from radiation alone. The results of these studies support further development and clinical application of genetic radiotherapy for human prostate cancer.

Adenoviridae↗