Rapid Case Ascertainment Research Articles

Comparison of Interviewed and Non-Interviewed Non-Hodgkin's Lymphoma (NHL) Patients in the San Francisco Bay Area

PURPOSE: To determine whether interviewed non-Hodgkin's lymphoma (NHL) patients differed from non-interviewed NHL patients and to revise the population-based risk estimate for NHL associated with HIV infection in homosexual men in the San Francisco Bay Area. Differences between study participants and non-participants are a concern in epidemiologic studies. Recruitment techniques can be modified when nonparticipation is a result of subject refusal. However, the solutions for nonparticipation due to death are less clear, especially when rapid case ascertainment (RCA) is used to identify newly diagnosed patients. METHODS: A large population-based case-control study was conducted in the San Francisco Bay Area between 1988 and 1995 to investigate risk factors for NHL. Nearly 1600 patients were interviewed and included in this study. A total of 1047 NHL patients were not interviewed because they had died prior to contact (602 patients) or we had received their RCA information after the study had ended (445 patients). We compared available demographic, clinical, and histologic profiles of the interviewed and non-interviewed NHL patients. RESULTS: Compared with the interviewed group, the non-interviewed group was younger, had more single HIV-infected homosexual men and a higher incidence of high-grade and “not-otherwise-specified” lymphoma. When categorized by sex and sexual preference, median age at diagnosis of NHL was the same for the interviewed and non-interviewed homosexual men. Combining interviewed and non-interviewed patients, the estimated risk for NHL associated with HIV infection in homosexual men [odds ratio (OR) = 50] is substantially higher than we had estimated in our earlier publications (OR = 20). CONCLUSIONS: High-grade lymphomas associated with poor survival in homosexual men are likely to be under-represented in case-control studies of NHL.

The case identification challenge in measuring quality of cancer care.

The delivery of quality care to all patients with cancer has been named as a national priority within the American health care system. This article addresses the issues critical to case identification in cancer quality measurement and recommends possible strategies for accurately identifying a population of cancer patients. We present the measurement issues associated with the basic challenges of case identification strategies for quality measurement. We discuss two basic challenges: (1) accurately identifying all patients with the defining characteristics (eg, a diagnosis of breast cancer), and (2) identifying only patients with these characteristics. Possible options for identifying newly diagnosed patients include using claims or other administrative data, cancer registries, cancer registry rapid case ascertainment, pathology laboratories, and physicians' offices. In the published literature, the sensitivity of claims varies from 75% to 95%, whereas central registries must have a 90% completeness rate to be certified. Most of these approaches, however, involve limitations to obtaining valid and comparable data across multiple settings. Using an existing data collection system staffed by skilled data collectors and managers should result in substantially more accurate and timely data. Registry officials and the government agencies that provide their support should be encouraged to adopt quality-of-care analyses as an important purpose of the registry system and to enhance their capacity to rapidly ascertain cases, collect the appropriate identifying information needed for patient contact, and verify stage at diagnosis. In order to meet the growing demand for timely, accurate information about quality of care, registries are likely to require additional support so they can enhance their capacity to rapidly ascertain cases, collect the appropriate identifying information needed for patient contact, and verify stage at diagnosis.

THE POSITIVE YIELD OF IMAGING STUDIES IN THE EVALUATION OF MEN WITH NEWLY DIAGNOSED PROSTATE CANCER: A POPULATION BASED ANALYSIS

We determine the positive yield of imaging studies performed on men with newly diagnosed prostate cancer. A prospective, population based survey was conducted on 3,690 men with prostate cancer diagnosed between October 1, 1994 and October 31, 1995. Cases were identified by the rapid case ascertainment systems used in 6 geographic regions participating in the Surveillance, Epidemiology and End Results Program. Based on information captured in primary medical record reviews we estimated the positive yield of bone scans, computerized tomography (CT) and magnetic resonance imaging. The positive yield of bone scan and CT was less than 5% and 12%, respectively, for all men with prostate specific antigen (PSA) 4 to 20 ng./ml., and less than 2% and 9%, respectively, for those who also had a Gleason score of 6 or less. Only men with PSA greater than 50 ng./ml. and those with Gleason scores 8 to 10 and PSA greater than 20 ng./ml. had positive yields greater than 10% and 20% for bone scan and CT, respectively. Imaging studies designed to identify metastases and/or extracapsular extension in men with newly diagnosed prostate cancer frequently have a low positive yield. Wide variations exist in the use of imaging studies and are associated with tumor factors, such as Gleason score and serum PSA, and nontumor factors, such as state of residence. More extensive cost-effectiveness analyses are needed to define appropriate guidelines for ordering imaging studies to optimize the positive yield among men with newly diagnosed prostate cancer.

Association between body mass and adenocarcinoma of the esophagus and gastric cardia.

The incidence of esophageal and gastric cardia adenocarcinoma is, for unknown reasons, increasing dramatically. A weak and inconsistent association between body mass index (BMI) and adenocarcinoma of the esophagus and gastric cardia has been reported. To reexamine the association between BMI and development of adenocarcinoma of the esophagus and gastric cardia. Nationwide, population-based case-control study. Sweden, 1995 through 1997. Patients younger than 80 years of age who had recently received a diagnosis were eligible. Comprehensive organization ensured rapid case ascertainment. Controls were randomly selected from the continuously updated population register. Interviews were conducted with 189 patients with adenocarcinoma of the esophagus and 262 patients with adenocarcinoma of the gastric cardia; for comparison, 167 patients with incident esophageal squamous-cell carcinoma and 820 controls were also interviewed. Odds ratios were determined from BMI and cancer case-control status. Odds ratios estimated the relative risk for the two adenocarcinomas studied and were calculated by multivariate logistic regression with adjustment for potential confounding factors. A strong dose-dependent relation existed between BMI and esophageal adenocarcinoma. The adjusted odds ratio was 7.6 (95% CI, 3.8 to 15.2) among persons in the highest BMI quartile compared with persons in the lowest. Obese persons (persons with a BMI > 30 kg/m2) had an odds ratio of 16.2 (CI, 6.3 to 41.4) compared with the leanest persons (persons with a BMI < 22 kg/m2). The odds ratio for patients with cardia adenocarcinoma was 2.3 (CI, 1.5 to 3.6) in those in the highest BMI quartile compared with those in the lowest BMI quartile and 4.3 (CI, 2.1 to 8.7) among obese persons. Esophageal squamous-cell carcinoma was not associated with BMI. The association between BMI and esophageal adenocarcinoma is strong and is not explained by bias or confounding. The carcinogenic mechanism, however, remains to be clarified. The increasing prevalence of obesity in western countries could be important in understanding the increasing occurrence of this tumor.

Environmental risk factors for primary malignant brain tumors: a review.

This review suggests that existing theories of carcinogenesis provide much of the necessary framework for understanding the etiologies of malignant gliomas. Most of the environmental risk factors associated with brain tumors involve exposures to infectious, chemical, or physical agents capable of inflicting genetic damage. It is equally important to recognize that some potential risk factors for brain tumors, if their association proves causal, suggest as yet unknown or undefined mechanisms of carcinogenesis. For example, the mechanisms through which extremely-low-frequency electromagnetic fields might induce cancer are unknown, but interest in this area is intensifying [165]. Large population based studies currently being conducted throughout the world will help to estimate the relative importance of some suspected factors. Several of the most serious limitations of previous studies can be overcome by careful study design including sample size planning to ensure adequate power for important hypotheses and subgroup analyses, systematic pathology review to enable analyses by histologie type, collecting sufficiently detailed exposure data to minimize recall problems and permit flexibility in classifications, and using rapid case ascertainment systems to minimize the need for interviews with proxies and concomitant reporting bias. Furthermore, as important genes for brain tumors are identified, they can be used to further refine subtype classifications and to improve sensitivity in the search for environmental culprits.