Automatic search for optimal conditions in clinical studies.

BACKGROUND: A program for an automatic search for the optimal conditions of important prognostic factors in clinical studies was developed. METHODS: The program was developed for the following steps: (1) Input of the maximum and minimum values and of the interval of the variable to be investigated. Automatic calculation of the Cut Points. (2) Division of the patient data into two groups at every Cut Point and calculation of survival rates. (3) Sequential calculation of P-values and chi-square values for the two sets of survival rates. To determine the usefulness of this program, the optimal irradiation dose was searched for 537 patients with non-small cell lung cancer. RESULTS: The P-value reached its minimum value and the chi-square value its maximum when the Cut Point was 5,925 cGy (0.0001 and 30.18). Between 5,925 cGy and 6,900 cGy, the P-value stayed at less than 0.05. CONCLUSION: Artificial errors in grouping by prognostic factors can be avoided and the search for optimal conditions can be conducted automatically and scientifically.

[Clinical quality assurance at institutions according to a patterns of care study. Japanese PCS Working Group].

The clinical quality assurance (QA) of an institution is important in any multiinstitutional prospective study. Patterns of Care Study (PCS) is a well-known study for QA activity in the United States. PCS is a nationwide retrospective study done by two-staged cluster sampling of institutions and patients and external audits. After data are accumulated, National averages on various survey items are calculated as a QA measure. In 1996, PCS was imported into the radiation oncology field in Japan with the support of the Ministry of Health and Welfare. Preliminary results showed significant differences in treatment process, structure, and preliminary outcome according to the stratification of institutions. These data can be useful in improving the structure and process at the institutional as well as the national level. PCS will also clarify the dissemination of positive clinical results into national practice.

A preliminary outcome analysis of the Patterns of Care Study in Japan for esophageal cancer patients with special reference to age: non surgery group.

BACKGROUND: The Patterns of Care Study (PCS) was imported to Japan from the United States in July 1996. A preliminary outcome analysis of the PCS for esophageal cancer patients in Japan was made with special reference to age, because the elderly population is rapidly increasing in Japan. PATIENTS AND METHODS: From July 1996 to February 1998, external PCS audits were performed for 37 institutions nationwide and detailed information of 561 esophageal cancer patients treated during the period 1992-1994 was collected by using the fifth PCS data format developed in the United States. This format was provided courtesy of the American College of Radiology. For this study, patients who had not undergone surgery (n = 336) were selected. The patients were classified into three age groups: < 65 years old (n = 119), between 65 and 74 years (n = 93), and 75 years or older (n =123). Cox's proportional hazards model was used for the statistical analysis, with survival, acute/subacute complication and late complication of grade 3 or more based on RTOG criteria, as the endpoints. RESULTS: Significant prognostic factors for the entire non-surgery group were Karnofsky Performance Status (KPS) (p = 0.0007), stage (p = 0.0001), and external irradiation dose (p = 0.0001). For the younger group, KPS (p = 0.0004), stage (p = 0.0197), and utilization of brachytherapy (p = 0.0010) were significant, while for the intermediate age group it was KPS (p = 0. 0027), history of pulmonary disease (p = 0.0339), stage (p = 0.0001), and external dose (p = 0.0001), and for the elderly group, stage (p = 0.0001) and external irradiation dose (p = 0.0224) were significant. Significant risk factors for complications for the entire group were stage (p = 0.0411), external dose (p = 0.0163), and stratification of institution (academic vs. nonacademic) (p = 0. 0114). Significant risk factors for the younger group were history of pulmonary disease (p = 0.0495) and external dose (p = 0.0037), and the other age groups showed no significant risk factors. CONCLUSION: Age was not a significant prognostic or risk factor for esophageal cancer patients in the non-surgery group treated with radiation therapy. Therefore, radiation therapy represented an important treatment modality for the elderly as well as for the younger esophageal cancer patients. External dose was a treatment-related prognostic factor for the elderly as well as for the intermediate age group.

National average for the process of radiation therapy in Japan by Patterns of Care Study.

BACKGROUND: A nationwide effort is in progress to establish the actual state of radiotherapy and its quality assurance (QA) in Japan by using the Patterns of Care Study (PCS). In this study, national averages are calculated with a limited number of patients. A calculation program for national averages was prepared and applied to the radiotherapeutic processes used for esophageal cancer patients entered in the PCS. METHODS: The calculation program for national averages, which were revised on the basis of differences between individual facilities and institutional strata, was developed in accordance with Sedransk's equation for the original PCS in the USA. National averages for several aspects concerning the sampled patients who had esophageal cancer between 1992 and 1994 were calculated with these procedures. Data for facilities and stratification of institution were simulated from a national structure survey of radiation oncology in 1990. RESULTS: Values of the national average by Sedransk's equation were different from those of the simple sample average. There were significant differences in radiotherapeutic processes among stratification of institutions. For esophageal cancer, national averages were 0.129 for applications of endoscopic ultrasound, 0.599 for 'all fields treated each day' and 0.088 for application of brachytherapy. CONCLUSION: National averages for radiotherapy could be calculated. The values obtained in this PCS will be a useful measure for future QA in radiation oncology and in other specialties in Japan.

Prognostic factors for patients with esophageal cancer treated with radiation therapy in PCS: a preliminary study.

PURPOSE: We investigated the prognostic factors, with special reference to age, for esophageal cancer patients, who did not receive surgery but were treated with radiation in the context of a Patterns of Care Study (PCS) in Japan. PATIENTS AND METHODS: The fifth PCS database format employed in the United States was used to collect information on 455 esophageal cancer patients by external audit. The data of patients who had not received surgery (n=252) were further selected and divided into two age groups, patients 75 years old or older (n=90) and patients younger than 75 years (n=162). Cox's proportional hazards model was used for the statistical analysis, with crude survival as the endpoint. Variables tested were age; Karnofsky performance status (KPS); history of pulmonary disease, cardiovascular disease, and diabetes; AJCC stage; external dose; treatment period; combination with chemotherapy; utilization of brachytherapy, and stratification of institutions. RESULTS: Statistically significant prognostic factors for all patients in the non-surgery group were KPS p=.0001), stage (p=.0001), and utilization of brachytherapy (p=.0102). For younger patients, KPS (p=.0001), stage (p=.0007), external dose (p=.0001), and utilization of brachytherapy (p=.0034) were significant, and for the elderly, stage (p=.0001) and external dose (p=.0006). CONCLUSION: Although this was a preliminary study, age was not a significant prognostic factor for esophageal cancer patients in the non-surgery group, and making the external dose more than 60 Gy appears to be effective for improving survival of elderly as well as younger patients.