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Biomedical subjects

W Wara

Publications and source records attributed to W Wara.

13 recordsLinked to original sources
PubMed1993

Beta test site report: gamma plan.

We describe our preliminary experience with a beta-test version of the Leksell Gamma Plan (LGP) treatment planning system. During this testing phase we used the LGP system to find an acceptable treatment plan and then transferred coordinates to the KULA system for final calculation. We find that the LGP system offers a fast way of optimizing shot placement and weighting, especially for complex treatments. The ability to display many MR and CT images on screen and to superimpose isodose lines on these images, as soon as the dose distribution has been calculated, allows adjustments to be made more rapidly than with the plotting approach used by the KULA system. This software is in beta-test, and is undergoing modification. Problems relating to our hardware configuration have been addressed with a newer workstation specified for the production system.

Computer Graphics↗
PubMed1991

Cognitive function in children with leukemia. Effect of radiation dose and time since irradiation.

The effect of two cranial radiation (CRTX) doses and the time since radiation therapy on cognitive functioning were studied in 35 children who completed therapy for acute lymphoblastic leukemia (ALL). The patients were grouped according to CRTX dose (2400 or 1800 cGy) and evaluated for general intelligence, academic achievement, and visual motor integration. Those who received 2400 cGy (n = 20) scored ten points below those treated with 1800 cGy (n = 15) on verbal intelligence quotient and achievement tests of reading, spelling, and arithmetic. The effect of time since radiation therapy on these measures of cognitive function was significant (P = 0.001 to 0.03); the effect of CRTX dose was not. Visual motor integration scores in both groups fell below the 33rd percentile. The effect of CRTX dose and time since radiation therapy on visual motor integration and performance intelligence quotient were not significant. Thus, the interval between treatment and the emergence of cognitive impairments may be longer after lower CRTX doses, and deficits in nonverbal areas such as visual motor integration may appear first. A larger study is needed to confirm these findings from a limited sample of long-term survivors of ALL.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1990

The treatment of medulloblastoma. Results of a prospective randomized trial of radiation therapy with and without CCNU, vincristine, and prednisone.

In a prospective randomized trial designed to study the effectiveness of adjuvant chemotherapy following standard surgical treatment and radiation therapy, 233 eligible patients with medulloblastoma were treated by members of the Children's Cancer Study Group and the Radiation Therapy Oncology Group. Eligible patients were randomly assigned to receive radiation therapy with or without adjuvant chemotherapy consisting of 1-(2-chloroethyl)-3-cyclohexyl-nitrosourea (CCNU), vincristine, and prednisone. The estimated 5-year event-free survival probability was 59% for patients treated with radiation therapy and chemotherapy and 50% for patients treated with radiation therapy alone, a difference which is not statistically significant. The 5-year survival probability was 65% for both groups. Although the treatment difference was not statistically significant when all patients were combined, in the small number of patients with more extensive tumors, event-free survival was better in the group receiving chemotherapy (48% vs. 0%, p = 0.006). In these latter patients the survival time is also significantly prolonged. Extent of disease (as measured by the M staging criteria described by Chang) and age at diagnosis were significantly associated with outcome; advanced disease and young age had a worse prognosis. The extent of tumor resection was not an independent prognostic factor. It is concluded that chemotherapy does not benefit patients with low-stage medulloblastoma, but may benefit those with more advanced stages of disease.

Adolescent↗
PubMed1989

Pineocytomas.

Six cases of histologically proven pineocytoma are reported. The diagnosis was established by surgery in five cases and at autopsy in one. All patients received focal radiation therapy (4500 to 5400 cGy). Two patients had local recurrences at 1 and 48 months and subsequently died of tumor. A third patient died of Alzheimer's disease 29 years after the initial presentation. Three patients are alive with no evidence of disease at 21+, 52+, and 84+ months after treatment. Tumor dissemination occurred after a local recurrence in one patient. We found no evidence of recurrence outside the irradiated field unless there was an initial recurrence at the primary tumor site. We recommend postoperative staging for all patients with pineocytoma and focal radiation therapy if local disease alone is found. Craniospinal radiation therapy appears to be justified only if tumor dissemination is documented on staging tests.

Adolescent↗
PubMed1989

The effectiveness of chemotherapy for treatment of high grade astrocytoma in children: results of a randomized trial. A report from the Childrens Cancer Study Group.

Fifty-eight patients with high-grade astrocytoma were treated by members of the Childrens Cancer Study Group in a prospective randomized trial designed to study the effectiveness of chemotherapy as an adjuvant to standard surgical treatment and radiotherapy. Following surgical therapy, patients were assigned randomly to radiotherapy with or without chemotherapy consisting of chloroethyl-cyclohexyl nitrosourea, vincristine, and prednisone. Treatment with chemotherapy prolonged survival and event-free survival. Five-year event-free survival was 46% for patients in the radiotherapy and chemotherapy group, and 18% for patients in the radiotherapy-alone group. Five-year survival was similarly improved. The differences in outcome due to treatment were statistically significant after correcting for imbalances in important prognostic factors (event-free survival, p = 0.026; survival, p = 0.067). The presence of mitoses or necrosis in the tumor specimen was associated with poorer outcome. Patients whose initial surgery was limited to biopsy, and patients with basal ganglia lesions, also had significantly worse outcome. Chemotherapy administered at the time of recurrence in a small number of patients did not produce any long-term survivors. This study is to our knowledge the only randomized trial to investigate effectiveness of chemotherapy in the treatment of high-grade astrocytoma in children.

Adolescent↗
PubMed1988

Primary central nervous system lymphomas in patients with AIDS.

Primary central nervous system non-Hodgkin's lymphomas are observed in approximately 1.9% of all patients with acquired immunodeficiency syndrome (AIDS). The yearly incidence of AIDS-associated tumors has surpassed the yearly incidence from all other causes and could become as frequent as low-grade astrocytomas by 1991. Patients' signs, symptoms, and radiographic studies are not specific for this lesion; brain biopsy usually is necessary to make a definitive diagnosis. Most tumors are high-grade lymphomas and are pathologically similar to the primary central nervous system lymphomas observed before the AIDS epidemic. AIDS-associated tumors respond readily to radiation therapy. However, patient survival remains limited owing to other manifestations of the syndrome.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Treatment of medulloblastoma with procarbazine, hydroxyurea, and reduced radiation doses to whole brain and spine.

Forty-seven patients with medulloblastoma were treated postoperatively with procarbazine, followed by craniospinal radiation therapy in combination with hydroxyurea. The radiation dose to the posterior fossa was 55 Gy; the spinal cord received 25 Gy and the whole brain 25 to 35 Gy (mean 33 Gy). Seventeen tumors recurred. Only one initial recurrence was in the spinal subarachnoid space; 10 (59%) were in the posterior fossa, and four (24%) were supratentorial. The estimated 5-year disease-free survival probability was 55%; the 5-year overall survival rate was 66%. Myelotoxicity occurred in 38% of patients, but in only one case was it severe enough to warrant reducing the total dose of radiation. It was concluded that good-risk medulloblastoma patients may be treated with radiation dosages as low as 25 Gy to the spinal axis and to the whole brain without increasing the risk of recurrence outside the posterior fossa. Chemotherapy with procarbazine followed by radiation therapy and hydroxyurea during radiation therapy was well tolerated and may play a role in reducing radiation dosages outside the posterior fossa.

Adolescent↗
PubMed1987

Brain-stem tumors in childhood: a prospective randomized trial of irradiation with and without adjuvant CCNU, VCR, and prednisone. A report of the Childrens Cancer Study Group.

Seventy-four children with a brain-stem tumor diagnosed between 1977 and 1980 were entered into a prospective study in which exploration and assessment for resection were optional, radiation treatment using standard methods was required, and randomization occurred with regard to the use of adjuvant chemotherapy (1-(2-chloroethyl)-1-nitrosourea, vincristine, and prednisone) or no further treatment. The overall 5-year survival rate was 20% and was not improved by the adjuvant chemotherapy program. An increased risk of infection was associated with the adjuvant therapy.

Adolescent↗