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Biomedical subjects

H Shirato

Publications and source records attributed to H Shirato.

At least 73 records · Page 4Linked to original sources
PubMed1998

Teratomas of the central nervous system: treatment considerations based on 34 cases.

OBJECT: The optimum clinical management of central nervous system (CNS) teratomas, particularly postsurgical adjuvant therapy, is still unclear, partly as a result of the tumors' low incidence. In this study the authors analyze 34 cases of CNS teratomas so that they may adequately indicate management of these lesions. METHODS: The median age of the 34 patients was 13 years. Twenty-seven patients treated between 1970 and 1991 were retrospectively reviewed. Four of these 27 patients died as a result of radical surgery; each of them had a teratoma involving the hypothalamus. After initial treatment, which included radiation therapy, 20 patients (48%) had died. In all seven cases of mature teratomas there was no recurrence. In two cases of immature teratomas in which there was complete surgical resection there was recurrence; however, salvage therapies were effective. Seven of eight patients with highly malignant teratomas died; for these patients salvage therapies, including repeated radiation and chemotherapy, failed. Seven patients who presented with CNS teratomas between 1992 and 1996 received adjuvant chemotherapy and radiation therapy according to a prospective study protocol. All seven patients were free from recurrence with a 70 to 100% Karnofsky Performance Scale score at a median follow-up period of 41 months. Patients with CNS teratomas rarely responded completely to chemotherapy or radiation therapy; an effective adjuvant therapy produced a partial response at best. CONCLUSIONS: Because teratomas show various responses to adjuvant therapy, a misdiagnosis of their histological subtype will lead to inadequate therapy. A diverse therapeutic protocol based on histological diagnosis is necessary to plan appropriate management. Treatment recommendations are discussed in detail in the article.

Adolescent↗
PubMed1997

Reduction of radiation-induced xerostomia in nasopharyngeal carcinoma using CT simulation with laser patient marking and three-field irradiation technique.

PURPOSE: Tumor control and reduction of postirradiation xerostomia in patients with nasopharyngeal carcinoma (NPC) using the three-field irradiation technique based on the CT-based simulation with laser patient marking was investigated. METHODS AND MATERIALS: Seventy-eight patients with NPC were consecutively treated between 1983 and 1993. In 33 patients treated before 1987, target volume was determined using a conventional x-ray simulator with a reference of CT images, and the primary site was treated by the conventional parallel-opposed two-field technique (Group I). In 45 patients treated from 1987, target volume was determined using a CT simulator slice by slice, the treatment field was projected onto the patient's skin by a laser beam projector mounted on a C-arm, and the primary site was irradiated by a three-fields (anterior and bilateral) technique (Group II). In Group II, the shape of each field was determined using a beam's eye view to reduce the dose to the bilateral parotid glands. The three-field technique reduced the dose to the superficial lobe of parotid gland to about two-thirds of the dose given by the two-field technique. Radiation-induced xerostomia was evaluated by clinical symptoms and radioisotope sialography. RESULTS: The 5-year survival rate and disease-free survival rate were 46.6 and 31.2% in Group I, and 46.8 and 46.5% in Group II. A large variation in the volume of parotid glands were demonstrated, ranging from 9 cm3 to 61 cm3 among patients treated with CT simulation. Forty percent of the patients in Group II showed no or mild xerostomia, whereas all of the patients in Group I showed moderate to severe xerostomia (p < 0.01). The radioisotope sialography study showed that the mean secretion ratio by acid stimulation was improved from 3.8% in the Group I to 15.2% in the Group II (p < 0.01). CONCLUSIONS: CT simulation was useful to determine the size and shape of each field to reduce the dose to the parotid gland, of which size varies largely among individual patients. The three-field technique based on CT simulation with laser patient markings is suggested to result in superior complication-free survival in terms of salivary dysfunction than did the conventional two-field technique with x-ray simulatior for NPC.

Adolescent↗
PubMed1997

Analysis of long-term treatment of intracranial germinoma.

PURPOSE: To determine an appropriate treatment policy for intracranial germinoma. METHODS AND MATERIALS: From 1976 to 1992, 51 patients with germinoma (18 with pathologically verified germinoma and 33 diagnosed as having germinoma by neuroimagings) were treated by radiation therapy. Various radiation doses and treatment fields were used. RESULTS: The 10-year cause-specific survival rate for pathologically verified and unverified germinoma was 100% and 96%, respectively. Relapses were noted in four patients, three of whom died from the disease. Two of the four patients with a tumor larger than 4 cm in gross diameter experienced relapse. Two relapses occurred in a nonirradiated spinal canal and two occurred in the irradiation area treated by 25 Gy in 10 fractions and 30 Gy in 20 fractions. No relapse was noted in patients in whom the whole ventricle field was determined precisely using three-dimensional treatment planning. Five patients who were followed at an outpatient clinic experienced significant late neurocognitive dysfunction, which set in after radiotherapy. CONCLUSION: After pathological confirmation, 40 Gy whole-ventricle irradiation using precise three-dimensional treatment planning is appropriate as a standard treatment for most intracranial germinoma.

Adolescent↗
PubMed1997

Stereotactic irradiation without whole-brain irradiation for single brain metastasis.

PURPOSE: The effectiveness of stereotactic irradiation (STI) alone without whole-brain irradiation (WBI) for a single metastatic brain tumor was analyzed retrospectively. METHODS AND MATERIALS: Forty-four patients with this condition were treated using radiosurgery (RS) alone or fractionated stereotactic radiotherapy (FSR) without WBI. RESULTS: The initial response rate was 92% and the overall local control rate was 84% (37 of 44 patients). A total of 39% (18 of 44) of patients experienced intracranial relapse outside the initial target area. Forty-eight percent (21 of 44) of patients required salvage treatment for intracranial relapse. All 7 patients who received WBI as salvage treatment required no further salvage treatment, but 5 of the 14 patients who received salvage STI without WBI required three to four treatments for brain metastasis. Late radiation damage was not seen with initial treatment but was observed with retreatment. The overall median survival time was 261 days, with a standard error of 64 days. Actuarial survival at 12 and 24 months was 34% and 9%, respectively. The actuarial survival rate was significantly affected by the existence of active extracranial disease (p = 0.041). CONCLUSION: The high response rate and short treatment period of STI alone are advantageous in the treatment of single brain metastasis in patients with active extracranial disease with WBI reserved for relapse. Because of the low complication rate, STI alone may be also useful in patients with good prognosis, without extracranial disease.

Aged↗
PubMed1997

Reducing nurses'. Workload using a computerized nursing support system linked to the hospital information system.

A computerised nursing support system (CNSS) linked to the hospital information system (HIS) was developed and has been in use for one year, in order to reduce the workload of nurses. CNSS consists of (1) a hand held computer for each nurse (2) desk-top computers in the nurses' station and doctors' rooms (3) a data server (4) an interface with the main hospital information system. Nurses enter vital signs, food intake and other information about the patients into the hand held computer at the bed-side. The information is then sent automatically to the CNSS data server, which also receives patients' details (prescribed medicines etc.) from the HIS. Nurses and doctors can see all the information on the desk-top and hand held computers. This system was introduced in May 1995 into a university hospital ward with 40 beds. A questionnaire was completed by 23 nurses before and after the introduction of CNSS. The mean time required to post vital data was significantly reduced from 121 seconds to 54 seconds (p < 0.01). After three months 30% of nurses felt CNSS had reduced their workload, while 30% felt it had complicated their work; after five months 70% noted a reduction and 0% reported that CNSS had made their work more complex. The study therefore concludes that the interface between a computerised nursing support system and the hospital information system reduced the workload of nurses.

Humans↗
PubMed1996

Radionuclide venography as a clue to the diagnosis of Budd-Chiari syndrome.

A patient was examined with radionuclide venography (RVG) to investigate unilateral leg oedema which might be due to deep vein thrombosis. RVG with Tc-99m MAA demonstrated no findings to suggest deep vein thrombosis of the right leg. However, collateral flow derived from the left common iliac vein and truncated inferior vena cava (IVC) were revealed. Contrast venography confirmed the obstruction of IVC and collateral flow from the left common iliac vein to the left ascending lumbar vein. It also showed the obstruction of hepatic veins and the patient was finally diagnosed as Budd-Chiari syndrome. Although unilateral leg oedema is an atypical symptom in Budd-Chiari syndrome, the findings on RVG led us to conduct further imaging studies to reach the diagnosis.

Budd-Chiari Syndrome↗
PubMed1996

Clinical application of the computer picture archiving and communicating system to stereotactic radiosurgery.

Stereotactic radiosurgery, a rapidly evolving technology, provides precise high-dose irradiation to brain lesions and tumors. A new method using digital subtraction angiographic images of a personal computer-image display terminal interfaced to our picture archiving and communication system (PACS) performs measurements and calculations of the coordinates of the location of the center of the lesion to be treated. The time required to calculate the coordinates was performed by three methods: hand calculation, digitizer method, and PACS method. These three coordinates were compared in 10 cases. The hand calculation method required approximately 50 minutes, the digitizer method required approximately 10 minutes, and the PACS method approximately 3 minutes. The difference is statistically significant (P < .001). The three methods were equally accurate. This type of PACS application using inexpensive personal computers interfaced more directly to a PACS is an emerging trend that facilitates wider access to images and to manipulating them for specialized applications.

Humans↗
PubMed1996

Evaluation of multi skin test in colorectal cancer patients and effects of serum immunosuppressive factor and cytokine production of peripheral mononuclear cells.

Decreased skin reactions using five kinds of recall antigens correlate d with the stage of colorectal cancer. Immunosuppressive factors in the serum (IS index) increased with the progression of the stage in cancer patients, but interleukin (IL)-I and IL-2 production in peripheral mononuclear cells (PBMC) did not correlate with the advance of the disease. In patients with low immunosuppressive factors, the score of skin reactions was significantly higher than that in patients with high immunosuppressive factors. Increased serum immunosuppressive factors seem to reduce skin reactions in the patients. Furthermore, significant difference in skin reaction score was observed between patients with high IL-1 production of PBMC and patients with low IL-1 production of PBMC. These results suggest that skin reaction might be controlled by serum immunosuppressive factors and IL-1 production of PBMC, and that the score of skin reaction using multirecall antigens is a useful parameter to learn the host immunity in colorectal cancer.

Adult↗
PubMed1996

Combined irradiation and chemotherapy using ifosfamide, cisplatin, and etoposide for children with medulloblastoma/posterior fossa primitive neuroectodermal tumor--results of a pilot study.

Ten children with newly diagnosed medulloblastoma/primitive neuroectodermal tumor of the posterior fossa were treated with total surgical resection, radiation therapy, and ICE chemotherapy regimen with ifosfamide (900 mg/m2, days 1-5), cisplatin (20 mg/m2, days 1-5), and etoposide (60 mg/m2, days 1-5) every 4 weeks for eight cycles. Four children under 2 years old were at first treated with eight cycles of ICE chemotherapy, and then irradiated. The ICE regimen was well tolerated by all children, with no irreversible adverse effects. However, dose reductions during the eight cycles were inevitable mainly due to myelosuppression. Complete remissions were achieved in eight of 10 patients at 1 month after completion of the treatment. One child showed recurrence 21 months after complete remission. The disease-free survival rate was 70% with a mean observation period of 24 months after surgery. The ICE regimen is a useful treatment modality for children with medulloblastoma. Further study is warranted to clarify long-term outcome in a number of patients.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1996

Long-term evaluation of radiation-induced brain damage by serial magnetic resonance imaging.

The long-term changes during late delayed radiation-induced brain damage were investigated by serial magnetic resonance (MR) imaging of eight patients over a mean follow-up period of 45 months after irradiation. The radiation damage appeared as an enhanced lesion on T1-weighted MR images with gadolinium-diethylenetriaminepenta-acetic acid (Gd-DTPA) at 3 to 30 months after radiotherapy (mean 12.8 months). In all patients, an abnormal high signal intensity area on T2-weighted imaging preceded the enhanced lesion. The volume and number of enhanced lesions continued to increase for 3 to 23 months (mean 10.3 months). The high signal intensity area on T2-weighted imaging simultaneously expanded. The lesions were subsequently stabilized, and in four long-term survivors, the Gd-DTPA-enhanced lesions then decreased in size, the intervals from onset to regression were 12, 13, 17, and 35 months (mean 19.3 months), respectively. However, two patients showed a relapse of the enhanced lesion with latent periods of 8 and 9 months, respectively. Finally, the radiation-damaged brain became atrophic including the high signal intensity area on T2-weighted images. Late delayed radiation-induced brain damage continues to progress for over a year and then regresses, but thereafter a relapse may occur.

Adolescent↗
PubMed1996

[Stereotactic irradiation for brain metastases using linear accelerator].

A stereotactic irradiation (STI) system using a linear accelerator was developed and its effectiveness for brain metastasis was investigated. The system consisted of a conventional linear accelerator, invasive fixation head frame (RADFRAME, Mizuho Ika Kogyo), and a tungsten collimator. The RADFRAME was developed to be used with any linear accelerators and with any dose planning systems. The accuracy of the irradiation was assured to be within +/-1.5mm. Fifty-one patients with metastatic brain tumors were treated using the system. The overall median survival time was 10 months. No difference in survival was observed between patients with a single lesion and patients with two or three lesions. Complete, partial, and minimal responses were obtained in 16 (39%), 18 (41%), and 7 (16%) lesions. These were comparable to the reported results of gamma knife treatment. A maximum dose of 25 Gy was suggested to be more effective than lower doses. Local control rate was higher in tumors with a diameter of less than 2.0cm (87.5%) than in larger tumors (60%). No difference in tumor response was observed among various histopathologic types. In a patient with a 25mm cerebellar metastasis from an adenocarcinoma of the lung, autopsy at 5 months after STI showed fibrinoid degeneration and hyaline deposition without residual tumor at the Gd-enhanced region on MRI. The efficacy of linac stereotactic irradiation was equal to that of gamma knife radiotherapy for metastatic brain tumors.

Adenocarcinoma↗
PubMed1995

The role of radiotherapy in the management of spinal cord glioma.

PURPOSE: To determine the role of radiotherapy in the management of spinal cord gliomas. METHODS AND MATERIALS: Thirty-six patients with spinal cord glioma treated between 1979 and 1993 were examined. The patients had 13 astrocytic tumors (7 astrocytomas, 4 anaplastic astrocytomas, 2 glioblastomas), 22 ependymal tumors (18 ependymomas, 4 myxopapillary ependymomas), and 1 unclassified glioma. Fifteen of the patients were treated by surgery alone, but the remaining 21 patients also received postoperative radiotherapy. Total resection was performed on 1 astrocytoma and 13 ependymomas. In general, 40-50 Gy/16-20 fractions/4-5 weeks were given after parital resection, but no radiotherapy was given after total resection. RESULTS: Actuarial survival was significantly better for patients with ependymal tumors than for those with astrocytic tumors (p = 0007), 5-year actuarial survival rates being 96% and 50% for patients with ependymal tumors and astrocytic tumors, respectively. For patients with ependymal tumors, there was no difference in motor function and survival between those with total resection and those with partial resection followed by radiotherapy. Actuarial 3-year survival was 80% for patients with astrocytomas and 40% for those with anaplastic astrocytomas plus glioblastomas. The difference in the degree of motor function between the patients treated with radiotherapy and those without radiotherapy was not statistically significant. One anaplastic astrocytoma and one glioblastoma patient have lived longer than 4 years after radical treatment including radiocordectomy, or irradiation using doses larger than the tolerance threshold of the spinal cord. CONCLUSION: Postoperative conventional radiotherapy is indicated after less than total resection of low-grade ependymal tumors and astrocytomas but not after total resection of ependymomas. Radiocordectomy may be an option for certain cases with high-grade astrocytic tumors.

Adolescent↗
PubMed1995

A mathematical model of the volume effect which postulates cell migration from unirradiated tissues.

PURPOSE: In order to simulate the large variation in tolerance doses for very small treatment volumes, we introduce a model which assumes the presence of cells which have migrated from unirradiated tissues. METHODS AND MATERIALS: In order to represent serial architecture, the new model adds a new parameter to the familiar expression for serial architecture. Data derived from the model is fitted to the dose-response data developed by Hopewell et al. (Hopewell, J.W., Morris, A.D. and Dixon-Brown, A. The influence of field size on the late tolerance of the rat spinal cord to single doses of X rays. Br. J. Radiol. 60: 1099-1108, 1987) using white matter necrosis of rat spinal cord. RESULTS: The new model with a cell-migration term more accurately describes the large differences in threshold doses for a very small treatment volume than a model without a cell-migration term. CONCLUSION: Although these results do not prove that cell migration is the mechanism behind the volume effect for very small volume, they do suggest that the probability of normal tissue complication is more accurately predicted by the new model.

Animals↗
PubMed1995

Simultaneous carboplatin and radiotherapy for all stages of head and neck squamous cell carcinoma.

The study investigated the toxicity and efficiency of the concomitant administration of radiotherapy and carboplatin to patients with head and neck carcinomas. Sixty-three patients with head and neck squamous cell carcinomas, other than nasopharyngeal cancer and Stage I (UICC) laryngeal cancers, were treated by external radiotherapy and four courses of carboplatin at a dose of 100 mg/m2 per week. In two patients, only three courses were possible due to renal toxicity. In the other 61 patients, toxicities were self-limiting and no patient required interruption of carboplatin administration. No patient required discontinuation of radiotherapy because of acute toxicity. Of 61 evaluable patients, a complete response (CR) was obtained in 11.5% and a partial response (PR) in 60.7% at 40 Gy. In 41 patients treated to 65 Gy (including two patients with maxillary sinus carcinoma, who were treated by debulking surgery), CR was obtained in 76.9% and CR+PR was 100% at the end of treatment. The actuarial survival rate of the 63 patients at 2 years was 69.2%, with a median follow-up period of 24.4 months. One of 12 patients who received salvage surgery after radical radiotherapy has died due to poor wound healing after the surgery. The schedule was safe, providing a weekly check of serum samples was possible. It is likely that the rate of local control and vocal cord preservation in laryngeal tumours might improve if concurrent carboplatin is used. Careful follow-up is required to determine the long-term effect of concomitant carboplatin administration.

Adult↗
PubMed1995

Superficial esophageal cancer: multicenter analysis of results of definitive radiation therapy in Japan.

PURPOSE: To assess the effectiveness of definitive radiation therapy in patients with superficial esophageal cancer. MATERIALS AND METHODS: Method of irradiation, local control rate, survival rate, and complications were assessed in 105 patients (89 men, 16 women; age range, 50-88 years) with superficial esophageal cancer treated with definitive radiation therapy at 15 hospitals in 1981-1990. RESULTS: All lesions were confirmed to be squamous cell carcinoma. The overall 5-year survival rate was 38.7%; the 5-year disease-specific survival rate was 71.0%. The 2-year local control rate was 83.0%. Late complications occurred in 16 patients. The prevalence of complications was relatively high in the group treated with intraluminal radiation therapy. CONCLUSION: Local control and survival rates in patients treated with radiation therapy were excellent, especially in the group treated with external and intraluminal radiation therapy; however, the optimal dose and optimal combination of external and intraluminal radiation therapy should be further assessed.

Aged↗
PubMed1994

Precise positioning of intracranial small tumors to the linear accelerator's isocenter, using a stereotactic radiotherapy computed tomography system (SRT-CT).

RT-CT was developed as a simulator using CT scan for radiotherapy. Following three-dimensional treatment planning using CT images, the treatment center and treatment fields are projected to the patients' surface by laser beam on the C arm. The prototype had an accuracy of 3 mm which was equivalent to conventional X-ray simulators but was not adequate for use in stereotactic radiotherapy. A new RT-CT system was developed to have a precise localization capability for stereotactic radiotherapy. Using this stereotactic RT-CT (SRT-CT) after three-dimensional planning, the treatment center is projected to the stereotactic frame automatically. In this study, the values of the x, y and z coordinates of the target center determined by SRT-CT are compared with those determined by the traditional method using CT localizing plates. The discrepancies were within 1.0 mm in 90% and 1.5 mm in 100% of 30 measurements in 16 patients. The disadvantages of SRT-CT may be that the accuracy of localization depends on the quality of calibration of laser beams. The traditional CT localizing method has superiority over SRT-CT because of its solid coordinates but its accuracy is vulnerable to alignment of CT fiducial marker plates. Therefore, the SRT-CT and traditional CT localizing methods would be complementary to each other for precise localization.

Brain Neoplasms↗