Biomedical subjects

T Dokiya

Publications and source records attributed to T Dokiya.

At least 19 recordsLinked to original sources

PubMed2001

Brachytherapy for prostate cancer in Japan.

The temporary implantation of iridium-192 (Ir-192) is available in Japan if the patient is isolated in a radiation control area during the treatment. In this study, brachytherapy for prostate cancer was preceded by using low-dose rate Ir-192. Twenty-six patients with localized prostate cancer were treated with brachytherapy since December 1997. The age of patients ranged from 61 to 82 (median 76) years and the initial serum prostate-specific antigen (PSA) level ranged from 4.3 to 141 (median 17.4) ng/ml. Ten to 14 needles with Teflon sheaths were introduced into the prostate via a transperineal approach and an Ir-192 wire was placed in each sheath. The dose-distribution curve based on computed tomography imaging was drawn and the irradiation time was calculated for the whole prostate to receive over 70 Gy. During the 1-22-month follow-up period, all cases with an initial PSA level of less than 25 ng/ml showed continuous PSA decrease without biochemical failure. Magnetic resonance imaging demonstrated tumor regression in all cases within 6 months after the treatment. One-year biopsy specimens from patients with PSA failure demonstrated viable tumor cells, and the specimens from patients with favorable progress revealed fibrosis replacement without any variable tumor cells. Characterization of nocturnal penile tumescence data and IIEF 15 score proved the minimal effect of the treatment on erectile function. No major side effects or complications were observed. Brachytherapy using Ir-192 is a less invasive and safe procedure, which is expected to become a standard treatment for localized prostate cancer patients with relatively low PSA levels.

Aged↗

PubMed2000

[Brachytherapy].

Explore the source record for details and available documents.

Brachytherapy↗

PubMed1999

Multi-institutional randomized trial of external radiotherapy with and without intraluminal brachytherapy for esophageal cancer in Japan. Japanese Society of Therapeutic Radiology and Oncology (JASTRO) Study Group.

PURPOSE: With the aim of improving the results of treatment of esophageal cancer, we designed this multi-institutional, randomized trial to establish the optimal irradiation method in radical radiation therapy for esophageal cancer by clinically evaluating external irradiation alone and in combination with intraluminal brachytherapy. METHODS AND MATERIALS: The study population consisted of patients with squamous cell carcinoma who were expected to be successfully treated with radical radiation therapy. The patients who could be given intraluminal brachytherapy at the end of external irradiation of 60 Gy were stratified into 2 groups. Patients assigned to receive external irradiation alone received boost irradiation of 10 Gy/week on a schedule similar to the previous one, and with the same or smaller irradiation field. Intraluminal brachytherapy was performed, as a rule, with the reference dose point set at a depth of 5 mm of the esophageal submucosa, and a total of 10 Gy was irradiated at a daily dose of 5 Gy, on a once-weekly schedule with low-dose-rate or high-dose-rate brachytherapy equipment. RESULTS: A total of 103 patients were registered, 94 of whom were analyzable, with 8 ineligible, and 1 for whom complete information was unavailable. The overall cumulative survival rate was 20.3% at 5 years. The cause-specific survival rate was 31.8% at 5 years. The cause-specific survival rate at 5 years was 27% in the external irradiation alone group and 38% in intraluminal brachytherapy combined group. There was no significant difference between the 2 groups (p = 0.385). However, in the patients with 5 cm or less tumor length, the cause-specific survival rate was 64% at 5 years in the intraluminal brachytherapy combined group, which showed a significant improvement over 31.5% in the external irradiation alone group (p = 0.025). In the patients with Stage T1 and T2 disease, cause-specific survival rates tended to be better in the intraluminal brachytherapy combined group than in the external irradiation alone group (p = 0.088). In the patients with more than 5 cm tumor length or Stage T3-4 disease, there were no significant differences between the two groups by treatment methods (p = 0.290). The incidence of early and late complications did not differ according to whether intraluminal brachytherapy was used. CONCLUSION: For the purpose of establishing the usefulness of intraluminal brachytherapy, further prospective randomized studies are necessary to evaluate the efficacy in tumors with short length and those with shallow invasion, or to assess the usefulness of intraluminal brachytherapy, as additional irradiation in large advanced tumors have been shown to have disappeared by diagnostic imaging after chemoradiotherapy with 60 Gy/6w external irradiation.

Adult↗

PubMed1999

High-dose-rate brachytherapy boost following concurrent chemoradiotherapy for esophageal carcinoma.

PURPOSE: To assess the efficacy, toxicity, and the optimum dose of high-dose-rate brachytherapy following chemoradiotherapy (CRT) compared with a historical group of patients treated with a combination of external beam and brachytherapy (RT alone). METHODS AND MATERIALS: Fifty-three patients with localized esophageal cancer received concurrent chemoradiotherapy followed by brachytherapy. The chemotherapy regimen was a combination of cisplatin 60 mg/m2 on day 1 and fluorouracil 600 mg/m2 continuous infusion from days 1-4 during the first and last week of external irradiation. Radiotherapy consisted of external irradiation to a total dose of 40-61 Gy (median 50 Gy) and brachytherapy to 8-24 Gy (median 16 Gy) in 2-4 fractions. RESULTS: Acute toxicity was well tolerated. A fistula occurred in one patient 1 week after completion of external irradiation. Local control was achieved in 32/53 (60%) compared with 42% of the RT group (p = 0.029). Local control rates of the CRT group were significantly better than those of the RT group in Stages II and III. Late toxicity (esophageal ulceration and strictures) occurred in 18 (34%) of the CRT group compared with 12% in the RT group (p = 0.013). Severe late toxicity (RTOG/EORTC criteria Grade 3-4) occurred in six patients (15%) whose chemotherapy was followed by 16-24 Gy via brachytherapy compared with 2.5% in the RT group (p = 0.010). CONCLUSION: Combined chemoradiotherapy and brachytherapy boost achieved better local control than radiotherapy alone. However, a high level of severe late toxicity was observed especially with 16-24 Gy via brachytherapy.

Adenocarcinoma↗

PubMed1999

Curative radiotherapy with high-dose-rate brachytherapy boost for localized esophageal carcinoma: dose-effect relationship of brachytherapy with the balloon type applicator system.

BACKGROUND AND PURPOSE: This study analyzed the feasibility, local control and toxicity in potentially curable patients with esophageal carcinoma treated with a combination of external irradiation and high-dose-rate (HDR) brachytherapy using a balloon type applicator system to minimize hot spots on the mucosa. MATERIALS AND METHODS: During the 9 years, 124 patients with esophageal carcinoma and no apparent extraesophageal spread were treated with 40-60 Gy of external irradiation followed by 8-24 Gy of HDR brachytherapy. The fraction size of brachytherapy was 4-6 Gy. We developed a new applicator with 15 mm external diameter inflatable balloons. The reference point was a point 12.5 mm depth from the mid source. The study end points were local control, late toxicity and palliative effect. RESULTS: All 124 patients completed the planned radiotherapy. Local control rate was 69/124 (56%). There was a trend toward better local control rate for T1 lesions with increasing dose via brachytherapy. Of 69 patients with local control, treatment-related ulcers occurred in 28 patients, leading to death in four. The incidence of ulcers increased with increasing brachytherapy dose; 1/6 with 12 Gy, 16/43 with 16 Gy, 6/ 12 with 20 Gy, 4/5 with 24 Gy. Esophageal benign strictures occurred in ten patients and in all cases developed from ulcers. The incidence of freedom from dysphagia was not dose-dependent. CONCLUSION: A combination of external irradiation and HDR brachytherapy with the balloon type applicator was feasible and well tolerated. Although better local control was achieved by a higher dose of brachytherapy, the higher dose caused more severe esophageal injury.

Adult↗

PubMed1998

[Radiobiological considerations for stereotactic irradiation].

Stereotactic radiosurgery (SRS: stereotactic irradiation [STI] delivered in a single high dose) was initially developed by Leksell for non-malignant brain lesions, but there has been increasing interest in using it to treat small primary brain tumors or metastases. In more recent years, stereotactic radiotherapy (SRT: fractionated STI) has been developed, but radiobiological factors have not been sufficiently evaluated in relation to these techniques. Larson classified potential STI targets into four categories according to whether the target tissue is early- or late-responding and whether it is embedded within or only surrounded by normal tissue. We have actually calculated biologically effective doses for these categories to determine the indications for SRS and SRT, and to be able to choose suitable SRT schedules. Based on our calculations, theoretically SRS would be recommended for AVMs and benign tumors having distinct margins separating them from surrounding normal tissue and SRT would be recommended for low or high grade astrocytomas without clearly defined boundaries and metastasis. Recommended SRT schedules would be 49 Gy/7 fractions, 52 Gy/8 fractions or 54.9 Gy/9 fractions completed within 2 weeks. However, clinically, these indications and SRT schedules should be modified according to the many other factors involved in individual cases, such as tumor size, presence of tumor necrosis, the patient's general condition, prognosis, and so on.

Brain↗

PubMed1998

[Schedule of stereotactic radiotherapy: a study considering the factors of repair and cell proliferation].

Stereotactic radiosurgery (SRS: stereotactic irradiation [STI] delivered in a single high dose) was initially developed by Leksell for non-malignant brain lesions, but there has been increasing interest in using it to treat small primary brain tumors or metastases. Recently, stereotactic radiotherapy (SRT: fractionated STI) has been recommended on the basis of radiobiological considerations for tumors in which both normal glial cells and tumor cells reside within the tumor margin. Strangely, the factors 'repair' and 'cell proliferation' have been neglected in the radiobiological evaluations of STI reported so far, mainly because of the complexity of the calculations. 'Half-time repair' which is the key value in the 'repair' factor may be larger for nervous tissue than for many other normal tissues because nerve cells have decreased ability to recover from damage. 'Cell proliferation' should be an important factor when the total radiation period is extended by applying SRT. In this study, we created models based on estimated 'half-time repair' and 'cell doubling time' and attempted to determine optimal SRT schedules. When repair and cell proliferation factors are also taken into consideration, the recommended SRT schedules would be 7 Gy x 7 fractions every other day for malignant tumors and 3.5 Gy x 12 fractions every other day for benign tumors. However, clinically, these schedules should be modified according to factors in individual cases, e. g., tumor size, presence of tumor necrosis, the patient's general condition, prognosis, and so on.

Brain↗

PubMed1996

[Theoretical considerations of dose-rate effect for clinical application: a study of pulsed brachytherapy].

Pulsed brachytherapy is starting to be used for patients with various kinds of carcinoma, in the expectation of fair treatment results without increasing the late radiation-induced damage. We calculated the early and late biologically effective dose (BED) of this modality to predict early and late radiation damage based on the linear-quadratic model (L-Q model). The way to set the values of alpha/beta and mu (factor of repair) in the L-Q model remains controversial. The value of alpha/beta has been fixed at 3Gy for the late effect and 10Gy for the early effect in recent studies. In this study, we applied these alpha/beta values to calculate the BED, however, the effects of its alteration ranged from 0.5Gy through 15Gy on BED were also analysed. We assumed mu = 0.5 (T1/2 = 1-2 hours) in this study, but we also tried to examine the effects of its variation. Our results indicate that pulsed brachytherapy is a safe treatment procedure even if the dose-rate ranges from 1Gy/hr through 100Gy/hr, but the fractionation number should be increased when using a very high dose rate. Pulsed brachytherapy should be applied cautiously for tissues with a small mu value, such as the spinal cord, because an extremely high late BED would be expected in such cases.

Brachytherapy↗

PubMed1996

[Pitfalls of hyperfractionation: theoretical considerations of effect of repair time on late radiation damage].

The need of radiation therapy in cancer treatment is increasing, however, the dose of radiation is limited by its late effects on normal tissues. Hyperfractionated radiotherapy was applied to patients with various kinds of carcinomas in the 1980s, expecting to improve tumor control rates. Some reports showed that the total radiation dose could be increased without increasing late radiation damage by using hyperfractionated radiotherapy. We calculated the early and late biologically effective doses (BED) for conventional and hyperfractionated radiotherapy to predict the early and late radiation damage based on the linear-quadratic model (L-Q model). Setting the values of the alpha/beta ratio and t1/2 (half time repair) in the L-Q model is still controversial, and few reports deal with t1/2. Assuming t1/2 = 0.5 hour, the total radiation dose can be up to 71 Gy by hyperfractionated schedule (1.2Gy/fr. 2 times/day) without increasing the late BED of conventional schedule (2Gy/day, total 60Gy). However, the late BED should be increased in tissues with a larger t1/2 value, even if applying the same hyperfractionated schedule. Thus, it is not recommended to apply the same hyperfractionated protocol to all organs.

Humans↗

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↗

PubMed1995

[Palliative radiotherapy for symptomatic osseous metastases].

Bone metastases are one of the most common and serious conditions requiring radiotherapy, but there is still a considerable lack of agreement on optimal radiation schedule. We analyzed patients with symptomatic osseous metastases from lung (72 patients) and breast (63 patients) carcinoma treated by palliative radiotherapy between 1983 and 1992. In this series, the incidences of symptomatic bone metastases appearing within 2 years after the first diagnosis of the primary lesion were 96% and 36% for lung and breast carcinomas, respectively. Thirty percent of bone metastases from breast carcinoma were diagnosed more than 5 years after the first diagnosis. Thus careful follow-up must be carried out for a prolonged period. Pain relief was achieved at almost the same rate for bone metastases from lung and breast carcinomas (81% and 85%, respectively), an the rapid onset of pain relief (15 Gy or less) was obtained in about half the patients for both diseases. The rapid onset of pain relief and the lack of association between the onset of pain relief and primary tumor argued against the conventional theory that tumor shrinkage is a component of the initial response. In contrast to the fact that almost all lung carcinoma patients had very poor prognoses, one third of the breast carcinoma patients were alive more than 2 years after palliative radiotherapy. Thus, the late effects of radiation, such as radiation myelopathy, must be always considered especially in breast carcinoma patients even when it is 'just' palliative radiotherapy for bone metastases.

Adult↗

PubMed1995

[Current status of radiotherapy for esophageal carcinoma].

Preoperative radiotherapy for esophageal carcinoma had no improvement on survival or locoregional control. The role of postoperative radiotherapy is limited to patients with residual tumor. According to the nationwide statistics of the results of radiotherapy alone, 5-year survival rate of superficial or Ep-Sm type was 26% and 32.5%, respectively. Intracavitary irradiation will improve not only survival but provide palliation of dysphagea. Now, it must be discussed the usefulness of radiotherapy from the viewpoint of cost-benefit ratio.

Brachytherapy↗

PubMed1992

The role of radiotherapy in the treatment of primary mediastinal seminoma.

Nine patients with primary mediastinal seminoma were treated with radiotherapy. All patients achieved complete response on chest radiography. None of the three patients treated with whole mediastinal irradiation relapsed. Four of the six patients with involved-field irradiation had marginal relapses, suggesting the efficacy of the whole mediastinal irradiation.

Adolescent↗

PubMed1992

Primary non-AIDS related brain lymphoma. Patterns of failure following radiotherapy.

Thirteen patients with primary brain lymphoma (PBL) were treated with radiotherapy. Three patients also had ocular involvement with retinal masses at initial presentation. All but one patient received conventional whole brain irradiation and, in addition, spinal irradiation, intrathecal methotrexate or orbital irradiation were given in two, two and four patients respectively. The radiation doses for involved sites ranged from 40 to 65 Gy, and for prophylactic sites from 30 to 50 Gy. After radiotherapy, all patients had complete regression of the tumor on computed tomography. Nine patients relapsed, 5 of them with brain recurrence. Two patients had ocular recurrence exclusively as their first relapse. The remaining two relapsing patients had bone lesions. One patient died intercurrently. As a result, only three patients are alive and free of disease after 16 to 36 months and all three received some adjuvant treatment in addition to whole brain irradiation.

Adult↗

PubMed1990

[Brachytherapy of prostatic carcinoma, 60Co high dose rate, remote after-loading methods].

Six patients with prostatic carcinoma, including 2 with Stage B, 2 with Stage C, 2 with Stage D1, received transurethral irradiation (TUI) using 60Co high dose rate, remote afterloading methods, in combination with external irradiation by 4 MV X-ray. Total tumor doses were 97.0 to 129.3 in TDF and needle biopsy performed 3 mo after the treatment proved to be free of cancer cell in 5 patients and almost no viable cancer cell in one patient. No adverse reactions were encountered in any patient. We believe that TUI is a useful treatment for prostatic carcinoma.

Aged↗

PubMed1990

[Assessment of cisplatin in concurrent use with radiotherapy in esophageal carcinoma--joint research among nationwide multi-facilities, primary results. Research Committee for Radiation and Cisplatin Treatment of Esophageal Carcinoma].

The effect of cisplatin in concurrent use with radiotherapy for esophageal carcinoma has been assessed as a theme of joint research among nationwide 40 facilities for 18 months from October, 1985, to March, 1987. As the subjects, non-operative cases, recurrent cases and metastatic cases diagnosed as esophageal carcinoma were enrolled. Regimens in 4 kinds were used for treatment and CDDP was used concurrently with radiotherapy in all the regimens. The results of classifying and totalizing the effects in 73 cases, of whom the local effects were analyzed, turned out to be: CR-25 cases, CR rate being 34.2% and PR-33 cases, the effective rate being 79.5%. As a result of aggregating the effects by major axis of X-ray image, CR and effective rates were found as 60 and 90% in the cases with the axes less than 5 cm; 36 and 79% in the cases with axes more than 5 cm and less than 10 cm; and 19 and 76% in the cases with the axes more than 10 cm, all respectively.

Aged↗

PubMed1989

Phase II randomized clinical trial of LC9018 concurrently used with radiation in the treatment of carcinoma of the uterine cervix. Its effect on tumor reduction and histology.

The clinical efficacy of LC9018, a biological response modifier prepared from heat-killed Lactobacillus casei YTT9018, used in combination with radiation was studied in a randomized controlled trial on 61 patients with carcinoma of the uterine cervix of Stage IIB or III. The combination therapy with LC9018 demonstrated a significant effect on tumor reduction, compared with radiation therapy alone, at the cumulative doses of 15-Gy and 30-Gy external irradiation (P less than 0.05). Histologic study confirmed that LC9018 also enhanced the therapeutic effect of the irradiation. Moreover, LC9018 seemed to be useful in protecting the patients from leukopenia during radiotherapy. This study suggests that LC9018, when used in combination with radiotherapy, will be an effective adjuvant immunotherapeutic agent. More studies in a large series of patients will, however, be needed to establish its long-term efficacy, safety, and effects on both prognosis and enhancing radiotherapy.

Adjuvants, Immunologic↗

PubMed1989

[A clinical study of the radiosensitization of aclarubicin].

Sixty six patients with an advanced or a relapsed cancer have been treated with a combination of radiation and aclarubicin (ACR). The average irradiation dose was 45 +/- 15 Gy, and the combined total dose of ACR ranged from 130 to 260 mg, depending upon the following differing schedules: 10 mg x 3 or 5/w, 20 mg x 2 or 3/w and 20 mg x 2/d x 2/w. The tumor response attained was 70%, including 30% who achieved a complete response. A high response rate also was observed in rather radioresistant cancerous tumor, such as those of the lung, stomach and esophagus. The adverse effects, such as anorexia, nausea, and so on, were found increase with an increase in the dose of ACR. It thus was concluded that for clinical usefulness, 10 mg of ACR should administered every other day in combination with a definite program of radiotherapy.

Aclarubicin↗