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Biomedical subjects

L G Kessler

Publications and source records attributed to L G Kessler.

At least 19 recordsLinked to original sources
PubMed1992

Representativeness of the surveillance, epidemiology, and end results program data: recent trends in cancer mortality rates.

BACKGROUND: Mortality, incidence, and survival rates are the primary measures used by the National Cancer Institute (NCI) to monitor cancer in the United States. The Surveillance, Epidemiology, and End Results (SEER) data system collects data on all cancers diagnosed among residents in geographically defined populations, which comprise about 10% of the U.S. population. This data system is the major component of the NCI system for tracking these rates. Thus, it is important to assess the degree to which SEER data are representative of the entire U.S. population. PURPOSE: National data on mortality, but not on incidence or survival, are available from the National Center for Health Statistics. These data provide a census against which mortality data from the subset of the SEER regions may be compared. METHODS: Multivariate regression analyses of age-adjusted mortality rates from 1975 to 1988, computed for the SEER areas and for the entire United States, were performed for race- and sex-specific data from 15 cancer sites. Representativeness was evaluated by testing for differences in trends and levels between the data from the U.S. population and those from the SEER Program. RESULTS: Data from the SEER regions reflected the correct direction of trend for all sites, although some race-, sex-, and site-specific differences existed for the magnitude of the trends and levels of mortality when compared with data from the U.S. population. CONCLUSIONS: The demonstration that data from the SEER population do occasionally yield mortality rates that differ from those for the entire U.S. population suggests that data from the SEER coverage population are, in some cases, not representative of the greater U.S. population. IMPLICATIONS: This issue is of particular relevance to the interpretation of incidence measures, computed from the SEER data, for which there is no national database. Future efforts should be directed at a better understanding of how the SEER population differs from the U.S. population so that SEER rates can be adjusted to be more nationally representative.

Age Factors↗
PubMed1992

The prevalence of cancer among adults in the United States: 1987.

No national data exist on the prevalence of cancer in the United States population. The authors report the first estimates of prevalence rates of cancer from a population-based sample of the adult population of the United States. Estimates are based on responses collected from the Cancer Control Supplements of the National Health Interview Survey, a population-based sample survey of all people older than 17 years of age in the United States in 1987. Of 44,123 adults questioned, 1593 said they had a nonskin cancer. In 1987, after adjustments, the overall prevalence rate of all types of cancer, excluding nonmelanoma skin cancer, was 3230 per 100,000 adults; the rates for men and women were 1930 and 4412, respectively. The authors estimate that, in 1987, 5.7 million adults in the United States were survivors of nonskin cancer, 3.3% of the adult population. Approximately 89,000 adults had cancer during childhood, or 1.6% of the total. Approximately 3.6 million people were at least 5-year survivors and 900,000 adults had their disease diagnosed during the year before interview. Despite the potential for underreporting and misclassification, these national estimates are in general accord with figures estimated from other sources. Increasing survival after cancer, especially childhood and adolescent cancer, indicates the importance of continued monitoring to provide information needed to plan for adequate health services.

Adult↗
PubMed1992

The relationship between age and incidence of breast cancer. Population and screening program data.

Despite extensive study of breast cancer incidence, including specific studies of the relationship between age and breast cancer incidence, the picture remains confusing. This article examines not only the relationship between age and breast cancer, but also trends over time related to this relationship to discern the underlying true age-incidence pattern. The age-incidence curve changes around the menopausal period, most likely due to hormonal changes 10 to 15 years earlier, flattens out in the 40 to 50 year old age range, and then increases as age increases. Recent data showing decreased risk of breast cancer incidence at older ages, e.g., older than 75 years of age, relative to younger ages, are likely an artifact of recent increases in breast cancer screening in the United States. This picture is consistent with increases in screening and with notions of lead time created by increased screening. The increase in screening that has changed the age-incidence relationship may eventually deliver benefits to United States women in terms of mortality deficits, but this is not guaranteed unless screening becomes routine practice and high-quality therapeutic intervention and follow-up occurs as well.

Age Factors↗
PubMed1991

Projections of the breast cancer burden to U.S. women: 1990-2000.

Although breast cancer incidence rates in the United States have been climbing for the last 40 years, recent trends have shown a more dramatic increase since 1982. This recent rise has been the subject of much study, and it is likely due in part to increased mammographic screening. A mathematical model incorporating the long-term incidence trend estimated from the Connecticut Tumor Registry and recent increases in availability of dedicated mammography machines is described and used to project incidence rates. Projections of breast cancer incidence rates among U.S. women ages 50 and over from 1990 to the year 2000 are developed. It appears that breast cancer incidence rates will continue to rise until about 1990 and then decline as screening rates stabilize.

Adult↗
PubMed1991

The impact of breakthrough clinical trials on survival in population based tumor registries.

Three statistical models are developed to study the impact that two breakthrough clinical trials (MOPP for Hodgkin's disease and PVB for disseminated testicular cancer) had on survival in the Connecticut tumor registry and the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) registry program. A segmented regression model is used in conjunction with the Cox semi-parametric proportional hazards model, as well as the parametric Weibull and exponential cure models. These models allow us to determine approximately when survival first began to improve dramatically, indicating that improved treatments had become available, and how long it took for survival to level off again indicating that the full population survival impact had been realized. In addition, the degree to which the parametric models fit allows us to determine if the survival improvements occur within a parametric family. Results of the modelling indicate that dissemination took approximately 11 years in Hodgkin's disease while only 3 years in disseminated testicular cancer. In both disease sites survival first broke with prior trends between the time that the breakthrough trial started and its publication, indicating that earlier moderately successful 'precursor' trials with combination chemotherapy may have initiated the improved population survival trends. Reasons for the difference in dissemination time in the two cancer sites are examined in order to understand what factors may be responsible for the speed of dissemination and effective utilization of new therapies.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1991

Estimating the treatment costs of breast and lung cancer.

The Continuous Medicare History Sample File (CMHSF) was used to derive an estimate of the lifetime direct medical expenses attributable to two chronic diseases, lung cancer and female breast cancer. These two cancers are the leading cancer causes of death in men and women in the United States. They inflict large costs on the population, both direct and indirect, but the costs have been difficult to measure. The primary obstacle to quantification is the intermittent and long-term nature of treatment for these diseases. A complete record of expenses cannot usually be obtained from one source, however, a review of all the national health surveys, as well as the Medicare statistical files identified the CMHSF, which is maintained by the Health Care Financing Administration in a format suitable for calculation of cumulative medical expenses. Some of the pertinent features of the CMHSF include the following: 1) it is a nationally representative sample of the Medicare population, 2) it is longitudinal covering an 8-year period from 1974 to 1981, 3) it captures the majority of medical expenses for each enrollee, and 4) it can be linked to other national data bases such as the National Death Index. Charges for three phases of cancer treatment were derived from the file: initial therapy, maintenance care, and terminal care. A method is described for computing the present value of life-time treatment costs from the phase-specific charges. The lifetime cost of treating breast cancer in 1984 dollars is $36,926 and lung cancer is $12,510.

Aged↗
PubMed1991

Black-white differences in cancer prevention knowledge and behavior.

Data from the 1987 National Health Interview Survey Cancer Control Supplement were used to estimate multivariate logistic regression models of diet change, mammography utilization, stool blood test utilization, and smoking. Predictor variables included race, sex, age, income, dietary concerns, and four knowledge-related variables: education and three measures of cancer prevention knowledge. When knowledge variables were included in the models, race was not a significant predictor of behavior, with one exception: among women, Blacks were found to smoke less than Whites.

Adult↗
PubMed1991

Cervical cancer screening: who is not screened and why?

BACKGROUND: The decline in death rates from cervical cancer in the United States has been widely attributed to the use of Papanicolaou (Pap) smears for early detection of cervical cancer. METHODS: Pap smear screening rates, beliefs about appropriate screening intervals and factors affecting screening were examined using 1987 National Health Interview Survey data. RESULTS: Results indicate that through age 69, Blacks are screened at similar or higher rates than Whites. Hispanics, particularly those speaking only or mostly Spanish, are least likely to have received a Pap smear within the last three years. Of women who had never heard of or never had a Pap smear, nearly 80 percent reported contact with a medical practitioner in the past two years, while more than 90 percent reported a contact in the past five years. Overall, the most frequently reported reason for not having a recent Pap smear was procrastinating or not believing it was necessary. CONCLUSIONS: Thus, in developing screening programs, Hispanics, particularly Spanish speakers, must be targeted. In addition, educational programs should target unscreened women who forego the test due to underestimating its importance, procrastination, or because their medical care provider did not suggest the procedure. Women must be intensively educated that Pap smears should be scheduled routinely to detect asymptomatic cervical cancer.

Adolescent↗
PubMed1991

Cancer awareness among African Americans: a survey assessing race, social status, and occupation.

Knowledge of cancer prevention and control was defined in terms of prevention, etiology, treatment, symptoms, cancer rates, screening, and detection examinations. A survey of 86 African Americans and 68 white Americans in Alameda County, California was completed in 1985. An index comprised of 69 knowledge items was assessed. A multivariate analysis of race, education, socioeconomic status, and occupation confirmed that these characteristics were independent predictors of knowledge. Blue collar work status was the most important predictor of low knowledge levels. African Americans were less knowledgeable than white Americans with regard to diet in preventing cancer and treatment modalities for cancer, and were most likely to perceive surgery as contributing to metastases. Low education and income status predicted low levels of knowledge. An important consideration in changing knowledge levels is the need to translate technical information about treatment and metastases in ways that are effective in reaching target populations at risk for low levels of knowledge. Cancer prevention and control programs need to develop materials and strategies that are responsive to communities whose members are predominantly African Americans or blue collar workers, or have low levels of education and income.

Black or African American↗
PubMed1990

Is the supply of mammography machines outstripping need and demand? An economic analysis.

The number of dedicated mammography machines installed in the United States has grown explosively. It is estimated that almost 10,000 machines will be installed by 1990, whereas the projected demand for screening mammography will require only approximately 2,600 machines, if the machines are used in a moderately efficient manner. The excess supply of mammography resources raises concern from an economic perspective for several reasons. First, such a condition means that health care resources are being used inefficiently. Second, the low average utilization rate of mammography equipment implied by these results necessitates charging a high price-over $100, on average-to cover costs. This price is above the $50 usually associated with low-cost screening mammography programs, and it may impede a desirable public health trend to increase use of mammography screening. Third, the existence of many mammography facilities operating at low capacity levels is inefficient from a health systems perspective, increasing the cost of quality assurance and medical record keeping. The current condition of excess supply is probably unsustainable over the long term.

Costs and Cost Analysis↗
PubMed1990

The knowledge and use of screening tests for colorectal and prostate cancer: data from the 1987 National Health Interview Survey.

Data based on the 1987 National Health Interview Survey are presented depicting factors associated with the knowledge and use of three tests for the early detection of colorectal and prostate cancer: digital rectal examination, fecal occult blood tests, and flexible sigmoidoscopy. The percentage of the at risk adult population who have ever heard of or had these tests is reported. The association of demographic, personal resource, and health system factors with knowledge of these tests is explored using multivariate logistic regression. Health system factors are most consistently associated with use of the tests and with knowledge. Family income, family size, education, knowledge of cancer early warning signs, and measures of encounters with the health care system are associated both with knowledge of and, independent of knowledge, with use of the tests. Residency in the non-South, being white or female, and having an optimistic attitude about cancer prevention are all factors associated with greater knowledge of the tests, but not greater use among those aware of the tests. Membership in a health maintenance organization is more strongly associated with knowledge and use of fecal occult blood tests than the other tests. No association was found between current smoking status and knowledge of or use of any of the tests.

Adult↗
PubMed1989

Breast cancer screening legislation in the United States.

We discuss some of the issues emerging from a powerful legislative movement for preventive services over the past three years. During this time an increasing number of states passed, considered, or are currently developing breast cancer screening legislation. Most of these laws require some form of third party payment for mammography or establish breast cancer screening programs. The legislation varies markedly with regard to periodicity of examinations, ages covered, type and extent of third party coverage, dosage regulation, and radiographic equipment standards. This shows a need for common standards. Legislation provides an essential incentive for a public health response to a serious problem, but more than laws are needed. Health care providers and the general public need to be aware and take advantage of the coverage provided as a result of legislation. Moreover, public health officials need to be aware that such legislation may lead to a demand for services that exceeds present capacity to deliver them.

Aged↗
PubMed1989

Test statistic and sample size for a two-sample McNemar test.

McNemar's (1947, Psychometrika 12, 153-157) test of marginal homogeneity is generalized to a two-sample situation where the hypothesis of interest is that the marginal changes in each of two independently sampled tables are equal. This situation is especially applicable to two cohorts (a control and an intervention cohort), each measured at baseline and after the intervention on a binary outcome variable. Some assumptions often realistic in this situation simplify the calculation of sample size. The calculation of sample size in a study designed to increase utilization of breast cancer screening is demonstrated.

Biometry↗
PubMed1988

Diet and cancer. Evidence from associations of multiple primary cancers in the SEER program.

The occurrence of multiple primary cancers may reflect common etiologic factors. We investigated the extent to which the diet and cancer hypothesis was supported by data from the Surveillance, Epidemiology, and End Results (SEER) Program on multiple primary associations. Cancers of the colon/rectum and prostate in men, and those of the breast, colon/rectum, and uterine corpus in women, were hypothesized a priori to be diet-related cancers. Of the eight multiple primary associations among diet-related cancers that were possible in men and women, relative risks (RR) of a second diet-related primary cancer developing after a first diet-related primary ranged from 1.06 to 1.43. The lower bound of the 99% confidence intervals (CI) for five of these associations exceeded 1.00, and fell between 0.95 and 0.99 for the other three associations. The observed multiple primary associations were compatible with the existence of common etiologic dietary elements. However, hormonal, immunologic, and medical care factors shared by these malignancies must be considered as alternative explanations for these findings.

Diet↗
PubMed1988

Temporal variation in nucleolar organizer region expression in bone marrow cells of individuals with leukemia.

Silver staining was used to study nucleolar organizer region (NOR) expression in bone marrow cells obtained at two or, in one case, three time points from each of six leukemia patients. Using three measures of silver positivity, we observed that NOR expression was influenced by both metaphase stage and time. Silver positivity decreased significantly from one metaphase stage to the next, from prometaphase through late metaphase. When this variable was controlled for, significant changes in NOR activity were documented in comparisons between disease stages in the patients examined. However, patterns of NOR expression were not consistently associated with disease stage. These results indicate that in previous reports both the metaphase stage effect and the temporally changing nature of NOR activity have, as unrecognized variables, influenced observations of heterogeneity in NOR expression.

Adult↗
PubMed1988

Projections of lung cancer mortality in the United States: 1985-2025.

Lung cancer has been the leading cause of cancer death in the United States for the larger part of this century. Increases in smoking prevalence from the 1900s through the 1950s have resulted in more than 100,000 deaths annually. Because of the changes during the last three decades in smoking prevalence, the decreasing tar content of cigarettes, and the increasing popularity of low-tar cigarettes, trends in lung cancer are difficult to predict. This article presents an analysis of smoking and lung cancer data using an age-period-cohort model for projecting lung cancer mortality through the year 2025. The projections are based on the initial parameterization of the model and on prevention objectives related to smoking behavior established by the National Cancer Institute. It is concluded that the recent trends in lung cancer are unlikely to be affected by changes in cigarette composition and consumption in the near term, but increasing the effectiveness of anti-smoking campaigns can have a considerable effect on lung cancer rates in the more distant future.

Adult↗