Neutron Therapy of Unresectable and Recurrent Rectal Cancer / 대한치료방사선과학회지

Total of 53 patients of unresectable and recurrent rectal cancer treated with neutron beam during the period from Oct. 1987 to Apr. 1992 were analyzed. Dose fractionation for the neutron only group was 1.5 Gy per fraction, 3 fraction per week, 21 Gy/41/2 wks for 42 patients out of 53(76%). Neutron only but modified fractionation schedule (10% more or less of total dose) was applied for 9 patients, and mixed team (neutron boost) was for 4 patients. Complete tumor response was obtained in 40 patients(76% response rate). Local control rate was 28 out of 53(53%). Statistically significant better prognostic factors for local control were age below 49 years old (15/22, 68%) than above 50 years old (13/31, 42%), male (20/32, 63%) than female(8/21, 38%), tumor size less than 5 cm and non-metastatic(16/24, 67%) than size more than 5 cm or metastatic(12/29, 4l%). Major complication had developed in 7 patients (13%). Two year overall survival rate by Kaplan-Meier method was 30%, but it was rised to, 47% when the tumor was less than 5cm non-metastatic.

Neutron therapy for prostatic cancer / 대한비뇨기과학회지

The neutron beam has higher relative biological effectiveness (RBE) than conventional X or gamma ray because it is densely ionizing radiation which is presented by high linear energy transfer (LET). This physical and radiobiological characteristic plays an important role in killing of cancer cells in the state of biologically radio-resistant to the conventional radiation. The rationale of high LET radiation in the application to clinical radiotherapy is summarized as, high oxygen enhancement ratio (OER), less repair of cell damage, and less dependence of radio-sensitivity on cell cycle. Neutron therapy alone or combined with conventional radiotherapy was performed in 12 patients with stage C or D1 prostatic cancer from Mar. 1987 to Dec. 1989 in Korea Cancer Center Hospital. Local control rate at the time of 24 months after therapy was 67% (4/6) in stage C and 67% (4/6) in stage DI. Two-year actuarial survival rate after therapy was 82% in stage C and 67% in stage D1. The problem of neutron therapy was relatively high incidence of major complication rate, but it could be lessened by the accumulation of experience for neutron therapy. We think neutron therapy to be one of adequate treatment modalities for local control of stage C or Dl prostatic cancer.

Primary Radiation Therapy of Malignant Salivary gland Tumors by Conventional Megavoltage Irradiation: Korea Cancer Center Hospital / 대한치료방사선과학회지

Retrospective analysis of survival rates was undertaken in the patients of 58 cases treated with conventional radiation therapy for malignant salivary gland tumors between January 1975 and December 1984 in Korea Cancer Center Hospital (KCCH). They were patients whose long-term follow-up was possible and who had refused surgery or had had recurrences postoperatively. Out of 58 patients, 25 patients (43.1%) had mucoepidermoid carcinomas and 24 patients (41.3%) adenoid cystic carcinoma. Total actuarial survival rates at 5 years and 10 years were 68.2% and 31.8% respectively, but disease-free survival rates, 43.2% and 13.0%, respectively. According to TNM stage, the survival rates at 5 years were 86.5% in T1, 40.0% in T2 + T3, and 0% in T4. In terms of histologic types, 5 years disease-free survival rate of adenoid cystic carcinomas (40.1%) was lower than that of mucoepidermoid carcinomas (49.8%) but overall survival rate (77.3%) was much higher than that of mucoepidermoid carcinomas (51.5%). Therefore, we concluded that the patients, who had had disease after failure of treatment, could survive during a certain period of time and their alive times were 2 years on the average. There was a difference in survival rates in the mucoepidermoid carcinomas in terms of histological grade of differentiation and it was a arbiter in prognosis: 5 YSR of low-grade was 78.8% and higher 2 times than that of high-grade. There was no difference in survival rates according to location and sex. The number of patients having minor salivary gland tumors was 6 cases and their actuarial 5 YSR was 32.3%. Consequently, prognostic factors which influence the survival rates of patients with malignant salivary gland tumors are thought to be 1) histological ubtypes 2) T and N staging (AJCC) 3) histological grade, especially in mucoepidermoids.