Estimation of time parameter of LQ-model in fractionated radiotherapy of medulloblastoma.

PURPOSE: To estimate the dose required to counteract accelerated proliferation, gamma/alpha, of medulloblastoma (MB) cells during fractionated radiotherapy. MATERIALS AND METHODS: Sixty-five patients with MB (local control rate at 5 years: 73%) treated between 1980 and 1990 at our university hospitals were analyzed. The gamma/alpha was estimated by applying the profile likelihood method to Cox's proportional hazards model including the maximum value of time-incorporated biologically effective dose, tBEDmax. The tBEDmax was conditionally calculated with various settings of alpha/beta, time to kick off accelerated proliferation, Tk, and gamma/alpha. Pretreatment T-stage, log(age+1), extent of removal, and use of chemotherapy and immunotherapy were also included in the multivariate model. RESULTS: When alpha/beta was taken to be 10 Gy, the estimate of gamma/alpha was 0.52 Gy/day (95% confidence limits: 0.29-0.75) for 0 day of Tk and was 0.55 Gy/day (0.30-0.80) for 21 days of Tk. The gamma/alpha values tended to be larger in the T3 subgroup and in the non-total removal subgroup than in all patients, by about 0.05 Gy/day and 0.1 Gy/day, respectively. When alpha/beta was taken to be 25 Gy, the estimated values were about 0.05 Gy/day smaller than these values. CONCLUSION: The estimated gamma/alpha values were considerably large. Therefore, it is preferable to take this consumed dose per day into consideration in planning and conducting treatments for MB.

Pathologically-proven intracranial germinoma treated with radiation therapy.

BACKGROUND AND PURPOSE: A retrospective multi-institutional study was conducted to survey what percentage of intracranial germinomas were treated with pathological confirmation before radiotherapy and to investigate the influence of field selection on outcome. MATERIALS AND METHODS: Thirty-seven percent of patients (41 of 110 patients) were pathologically confirmed before radiotherapy during the past 16 years at eight institutions in Northern Japanese prefectures. Pathological confirmation was obtained in 26, 37 and 53% of cases during 1978-1983, 1984-1989 and 1990-1994, respectively. All 110 patients were examined using computed tomography (CT) scans. Among the 41 patients with pathologically confirmed germinoma, radiation fields were craniospinal in 23 patients, whole-brain in 10 patients and local without ventricle inclusion in eight patients. RESULTS: For the 41 patients with pathologically confirmed germinoma, the actuarial and cause-specific survival rates were 91/94% at 5 years and 87/90% at 10 years, respectively. The relapse-free survival rate at 10 years was 90. 76 and 22% for the craniospinal field, whole-brain field and local field without ventricle inclusion, respectively. CONCLUSION: Pathological confirmation was obtained in only 37% of CT-scan era cases, although the confirmations were more commonly carried out later in the study period. Limited local irradiation alone without ventricle inclusion cannot be recommended for localized tumors even with the help of CT scanning.

Retrospective multi-institutional study of radiotherapy for intracranial non-germinomatous germ cell tumors.

The treatment outcome of 24 patients with pathologically-proven non-germinomatous germ cell tumor was retrospectively investigated to determine the effectiveness of radiotherapy. The patients were divided into three groups as follows: group 1, five patients with mature teratoma with or without germinoma; group 2, six patients with immature teratoma with or without germinoma; group 3, 13 patients with other highly malignant tumors. The overall actuarial survival and relapse-free rates at 5 years were 82% and 59%, respectively, with a median follow-up period of 62 months. The actuarial relapse-free rate at 5 years was 100% for group 1, 63% for group 2 and 44% for group 3. There was no difference in the relapse-free rates between total resection and partial resection. Usage of chemotherapy was adversely related to survival probably due to selection bias. No local failure was observed with 10 Gy or more for group 1,40 Gy or more for group 2 and 54 Gy or more for group 3. In groups 1 and 2, there was no spinal relapses without craniospinal irradiation. In group 3, three of eight patients who did not receive craniospinal irradiation and none of five patients who received craniospinal irradiation experienced spinal relapse. In conclusion, highly malignant GCTs show a high incidence of spinal metastasis and craniospinal irradiation may reduce the risk of spinal metastasis. Radiation dose and volume are to be determined according to the histopathological aggressiveness.

Concurrent radiotherapy and chemotherapy with protracted continuous infusion of 5-fluorouracil in inoperable esophageal squamous cell carcinoma.

PURPOSE: The feasibility of a concurrent chemoradiotherapeutic protocol for patients with inoperable esophageal squamous cell carcinoma was tested. METHODS AND MATERIALS: Concurrent chemoradiotherapy using protracted low-dose continuous infusions of five-fluorouracil (5-FU; 250-300 mg/m2/24 h) and standard external beam irradiation was given to 28 patients with inoperable esophageal squamous cell carcinoma between November 1991 and June 1993. RESULTS: For 25 patients receiving a total dose of > or = 60 Gy and concurrent 5-FU infusion for more than 5 weeks, the complete response rate was 52%. Local progression-free rate in this chemoradiotherapy group was significantly higher than the historical controls treated by radiotherapy alone (p < 0.05). A multivariate analysis revealed the treatment scheme (concomitant chemoradiotherapy vs. radiotherapy alone) to be a significant factor in local control (p < 0.01). Swallowing pain (39%), anorexia (39%), and nausea (32%) were the most frequent early reactions. Serious late radiation complications have not been observed. CONCLUSION: The concurrent chemoradiotherapy using protracted low-dose continuous infusion of 5-FU and standard radiotherapy is an effective and safe method to obtain a local control in inoperable esophageal squamous cell carcinoma.

Cancer of the oropharynx developed after radiotherapy and chemotherapy for Hodgkin's disease--a case report.

A case of oropharyngeal squamous cell cancer occurring in the radiation field for Hodgkin's disease is reported. The second cancer was diagnosed six years and one month after the patient received 40 Gy/25 fractions. The patient also received salvage chemotherapy two years and six months after the primary radiotherapy. In a review of the world literature, we found 22 cases of head and neck cancer excluding the thyroid gland occurring after radiotherapy alone or radiotherapy combined with chemotherapy for Hodgkin's disease. Although second cancers in the head and neck area after Hodgkin's disease have rarely been reported, those patients cured of the disease should be followed up carefully for a long period of time.

Afterloading technique for interstitial irradiation of lesions in deep-seated organs.

An afterloading procedure using iridium 192 seeds was developed for the control of both localized primary lesions that are difficult to remove and superficial residual lesions that remain after the partial removal of tumors in relatively inaccessible, deep-seated organs. This technique makes possible the delivery of a minimal radiation dose to lesions in deep-seated organs. Fewer complications result, the seeds can be adjusted at appropriate intervals in proportion to the amount of radioactivity desired, and radiation exposure to personnel can be reduced. This paper describes the techniques and apparatus used to place the seeds in the tubing. Primary lesions of the urinary bladder, the prostate gland, and the esophagus, residual lesions in the brain and lung, and metastases in intrapelvic lymph nodes were treated. No technical difficulties or complications were encountered. Radiation exposures to personnel were minimized. The results indicate that the procedure has practical applications.