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Biomedical subjects

L J Peters

Publications and source records attributed to L J Peters.

266 records · Page 15Linked to original sources
PubMedDate not supplied

Resection of advanced cervical metastasis prior to definitive radiotherapy for primary squamous carcinomas of the upper aerodigestive tract.

Thirty-five previously untreated patients with stage IV squamous cell carcinoma of the upper aerodigestive tract with advanced neck disease (mass greater than 3 cm) but with primary lesions thought to be locally controllable with radiotherapy were selected between 1972 and 1988 for treatment by neck dissection followed by radiotherapy; postoperative to the neck and definitive to the primary. Limited neck dissections spared muscles, nerves, and vasculature structures unless clinically involved with cancer. All patients received at least 50 Gy, postoperatively, to the entire neck with doses of up to 75 Gy being delivered to the primary treatment portals. Regional (neck) failure occurred in 11% (4 of 35) patients. Overall, 5-year survival from cancer was 55%. Multiple levels of neck involvement were associated with poorer survival than a single large node; however, the difference was not statistically significant. Delay in the institution of radiotherapy following surgery adversely affected survival (p = 0.01). This study demonstrates that in selected patients it is possible to resect advanced nodal metastasis prior to treating the primary with radiotherapy without compromising cancer control.

Adult↗
PubMedDate not supplied

Electron beam therapy for eyelid carcinomas.

Forty-six (85%) basal cell and eight (15%) squamous cell carcinomas of the eyelids were treated with electron beams between 1963 and 1983. Lesion sizes ranged from microscopic to 4 cm, with 28 lesions larger than 1 cm. Thirty-eight lesions were treated with radiotherapy after incisional biopsy, and 16 were treated after excisional biopsy (specimens showed positive margins). Doses varied from 45 to 72 Gy, with daily fractions ranging from 2.12 to 4.0 Gy. There were six disease recurrences (10.9%): three in the treatment field and three at the treatment margin. Four of six recurrences were subsequently controlled by limited surgical excision and repair with preservation of the eye, whereas the other two required enucleation. Treatment sequelae such as skin atrophy, telangiectasis, and cosmetic results were evaluated in terms of radiotherapy parameters, pretreatment surgery, and size of the lesion. In 44 patients, the overall cosmetic result was judged as good to excellent, five patients had a mild to modest degree of deformity, and five had significant deformity. Such deformity was usually associated with tumor destruction or previous surgery. No major complications were noted.

Aged↗
PubMedDate not supplied

Enhancement by misonidazole of metastatic tumor nodule formation in the lungs of mice.

Investigations were performed to determine whether misonidazole, a hypoxic cell radiosensitizer, influences formation of tumor nodules in the lung of C3Hf/Kam mice and whether it affects the enhancement of tumor nodule formation caused by local thoracic irradiation (LTI). Cells from a chemically-induced fibrosarcoma (FSa) and a spontaneously-developed fibrosarcoma (NFSa) formed twice as many tumor colonies in the lungs of mice that received misonidazole as in untreated mice. The effect was observed only with doses of misonidazole of 1 mg/g or higher given within 2 days prior to i.v. injection of tumor cells. A similar twofold amplification of the effect of LTI occurred when 1 mg/g misonidazole was given 30 min before or 0.5 to 2 hours after irradiation. This increase was independent of the dose of LTI and the absolute number of tumor nodules in the lung. The mechanistic possibilities and clinical relevance of the misonidazole effect are discussed.

Animals↗
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Spontaneous metastasis: random or selective?

Spontaneous lung metastases from an infrequently metastasizing fibrosarcoma and a more highly metastatic mammary carcinoma showed no increased capacity for generating primary tumors with greater metastatic potential when transplanted into either normal or whole-body-irradiated syngeneic mice for up to six isotransplant generations. Rather, successive generations varied in their metastatic behavior, tending towards decreasing metastatic efficiency. These data support the view that spontaneous metastases are determined more by random survival of intravasated tumor cells than by the selection of preexisting metastatic cell variants.

Animals↗
PubMedDate not supplied

Concomitant development of granulocytosis and enhancement of metastases formation in tumor-bearing mice.

The experiments reported here show concomitant development of granulocytosis and enhancement of metastasis formation in C3Hf/Kam mice bearing NFSA fibrosarcoma. Both phenomena developed at approximately 2 weeks after s.c. transplantation of tumor cells, at a time when the tumor was approximately 10 mm in diameter. The number of granulocytes in the blood doubled approximately every 3.5 days, reaching about 30 times control levels shortly before the death of the mice. The magnitude of the metastasis enhancement formation by i.v. injection of tumor cells was three to four times the control value. Mice bearing NFSA had a significant increase in the number of endogenous CFUs. Plasma from NFSA-bearing mice and medium from cultured NFSA cells stimulated in vitro growth of granulocyte and macrophage colonies from normal bone marrow cell precursors, and induced granulocytosis upon i.v. injection into normal mice. This shows that NFSA tumor secretes factor(s) with potent granulopoietic activity. Injection of plasma from tumor-bearing animals followed by i.v. injection of NFSA cells did not lead to the enhancement of metastasis, implying that granulocytosis might be rather concomitant manifestation than a causative factor of the enhancement of metastasis formation. Importance of granulocytosis as a paraneoplastic manifestation during tumor growth is discussed.

Agranulocytosis↗
PubMedDate not supplied

Increase in radiosensitivity of lung micrometastases by hyperbaric oxygen.

Four-day-old artificial pulmonary micrometastases of two murine fibrosarcomas, designated FSA and NFSA, showed increased sensitivity to ionizing radiation by a factor of 1.13 when animals were exposed to hyperbaric oxygen breathing before and during irradiation, implying the presence of hypoxia in the micrometastases. At the time of irradiation the diameter of FSA and NFSA metastases was smaller than 200 and 100 microns, respectively, which, on the basis of oxygen diffusion, could not be responsible for hypoxia. It is assumed that hypoxia of micrometastases is passive, reflecting the radiobiological hypoxia of lung tissue that could exist under normal breathing conditions.

Animals↗
PubMedDate not supplied

Gadolinium neutron capture therapy for brain tumors: a computer study.

A Monte Carlo computer study of the total dose distribution from neutrons and prompt gamma emissions (but excluding the contribution from conversion and Auger electrons) for gadolinium neutron capture therapy of brain tumors has been carried out in order to test the theoretic feasibility of this modality using commercially available magnetic resonance contrast media. The three-dimensional dose distribution calculations were performed in a spherical head phantom with a spherical tumor at the center. Potentially achievable gadolinium concentrations of 150 micrograms/g of tissue in tumor and 3 micrograms/g in normal tissue were assumed with enrichment to 79.9% gadolinium-157, as supplied by Oak Ridge National Laboratory. Irradiation was assumed to be with a 2-keV monoenergetic cylindrical epithermal neutron beam having a radius of 4 cm. The three-dimensional thermal neutron fluence resulting from the 2-keV beam propagation through the tissue was modeled. For a single neutron beam, the maximum dose is delivered within the tumor but the dose is very inhomogeneous across the tumor volume due to rapid decrease of thermal neutron fluence with depth. Two parallel opposed neutron beams deliver to the interface of normal and malignant tissue 70%-80% of the maximum dose received at the center of the tumor. To deliver an average tumor dose of 500 cGy in 10 min would require a 2-keV source neutrons number of 8.0 x 10(11) per s within the geometry of the beam.

Brain Neoplasms↗
PubMedDate not supplied

Radiation therapy with hyperbaric oxygen at 4 atmospheres pressure in the management of squamous cell carcinoma of the head and neck: results of a randomized clinical trial.

PURPOSE: The purpose of this study was to present the results of a randomized trial evaluating HBO-4 in combination with hypofractionated radiation therapy in patients with locally advanced squamous cell carcinoma of the head and neck (SCCHN). METHODS AND MATERIALS: Between April 1974 and December 1975, 48 patients with locally advanced unresected SCCHN, referred for primary radiation therapy, were randomized to radiation delivered in air in two fractions of 12.65 Gy over 21 days to a total of 25.30 Gy (air, n = 25); or radiation under HBO-4 in two fractions of 11.50 Gy over 21 days to at total of 23.00 Gy (HBO-4, n = 23). The HBO-4 was administered under general anesthesia to minimize patient discomfort and potential problems with seizures associated with rapid compression to 4 atmospheres. Patients were monitored regularly by the radiation oncologists for toxicity, response, local control, and survival. The original hospital records, radiation records, and hyperbaric treatment logs were recently reviewed, and all data were entered onto a computerized database for the current analysis. The results of this trial have not previously been published. RESULTS: The air and HBO-4 arms were evenly matched with respect to age, sex, performance status, hemoglobin level, primary site, and stage of disease. Acute toxicities were acceptable with no significant differences between the two treatment arms. A trend toward excess severe late complications were noted in the hyperbaric arm (12 vs 7). There was a highly significant difference in complete clinical responses between the two arms, with 21/25 in complete dinical responses in the HBO-4 arm compared with 13/25 in complete clinical responses in the air arm, and a statistically insignificant trend toward improved 5-year local control in the HBO-4 arm (29% vs 16%). There were no significant differences between the two arms with respect to 5-year survival, distant metastasis, or second primary tumors. CONCLUSIONS: Long-term outcome from this historical randomized trial demonstrate substantial improvements in response rate with the use of HBO-4. The hypofractionation scheme used in the trial resulted in relatively low local control and high complication rates in this group of patients with very advanced SCCHN. However, these results support the theory that radioresistant hypoxic cells limit the radiocurability of SCCHN. Further investigations addressing the hypoxic cell problem with hypoxic cytotoxins or hypoxic cell sensitizers in combination with radiation therapy using more conventional fractionation schemes are warranted.

Atmospheric Pressure↗
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A role for T lymphocytes in the antitumour action of systemic C. parvum.

The frequency of tumours arising from s.c. injection of a syngeneic chemically-induced fibrosarcoma (Fsa) was not influenced by systemic administration of C. parvum (day + 3) except when doses less than the TD50 were injected. Then the number of takes was increased. The tumour normally grows progressively however regression was frequent in intact mice treated with C. parvum. Tumour regression did not occur in T cell-depleted mice treated in the same way. Splenic T cell-enriched populations of cells taken from Fsa-bearing C. parvum-treated mice caused tumour regression when adoptively transferred to Fsa-bearing T cell-depleted mice. Although this assay measures systemic rather than intratumoral T cell activity, it is proposed that C. parvum-induced regression of the fibrosarcoma is to a large extent due to enhanced T cell reactivity.

Animals↗
PubMedDate not supplied

In vivo transfer of antitumor activity by peritoneal exudate cells from mice treated with C. parvum.

We have investigated whether peritoneal exudate cells (PEC) from C. parvum (CP) treated (C3Hf/Bu mice could transfer in vivo the resistance against a syngeneic fibrosarcoma (FSa). Inhibition of tumour development and prolongation of survival of recipients were observed when CP-activated PEC were admixed with FSa cells before their intraperitoneal (ip) or subcutaneous (sc) injections into normal mice. The antitumour activity increased with the increase of the ratio of effector to target cells. Heat killed CP-PEC were unable to transfer the resistance. Also, pretreatment of recipients with 600 rads whole body irradiation (WBI) substantially reduced the efficacy of CP-PEC. Reconstitution of WBI mice with mixed normal spleen and lymph node cells, or spleen cells alone, or bone marrow cells did not restore the antitumor activity of transferred CP-PEC. In fact, reconstituted mice showed a further reduction of transferred antitumor resistance. CP-PEC activity was also inhibited in sc transfer experiments when normal PEC, spleen cells, T-cells or even fetal fibroblasts were admixed with tumor cells and CP-PEC. Possible reasons for the failure of WBI recipients to be fully protected by transferred CP-PEC are discussed.

Animals↗
PubMedDate not supplied

Role of radiotherapy in the primary management of mucosal melanoma of the head and neck.

Historically, radiotherapy has played a very small role in the management of mucosal melanoma, largely because the disease has been characterized as radioresistant. Recent observations regarding the radiobiology and clinical response of cutaneous melanoma have prompted investigators to reevaluate the role of radiotherapy in mucosal melanoma. A series of reports published during the last decade using radiotherapy alone have documented complete response rates of 50-75% with durable long-term control in half to two thirds of the complete responders. These data, taken in conjunction with the high rate of local failure after surgery alone, suggest that radiotherapy would have a useful role as a surgical adjuvant in a combined modality approach, as well as being of value in the primary management of unresectable disease. Guidelines for management based on the available data are presented.

Head and Neck Neoplasms↗