Palliative treatment of Ewing's sarcoma.
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Biomedical subjects
Publications and source records attributed to C R Smart.
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There is a great deal of indirect, nonexperimental evidence that a pattern of earlier-stage disease at diagnosis has a better outcome. Increased early detection activities can change, these stage patterns while various biases and the question of generalizability need to be kept in mind in their interpretation. The indirect evidences of possible benefit from early detection activities includes an increase in the number of cases detected, a pattern of more early- and less advanced-stage cases, an increase in the overall site-specific survival rate, and a decrease in the case fatality rate. Unless these intermediate markers are favorable, it is unlikely that early detection will reduce mortality. In addition, one should also differentiate a reduced incidence or a change in treatment as a cause for reduced mortality.
The U.S. Preventive Services Task Force evaluated the medical literature, utilizing strict criteria to judge the merits of experimental trials designed to show benefit in screening for cancer. For individuals at normal risk, the task force was not able to make recommendations for or against screening for colorectal, prostate, skin, oral, or testicular cancers. Only one physical-examination cancer-screening procedure has ever been tested in a randomized trial. During the past 27 years, the National Cancer Institute (NCI) has funded six randomized screening trials. Thus far, only one has shown a decrease in mortality. Recognizing the limitations of such trials, the NCI published "Working Guidelines for Early Cancer Detection." Designed for the practicing physician, these guidelines were based upon the best available evidence and on the judgment of representatives of medical professional organizations.
Over the past year, the National Cancer Institute has altered its guidelines for early breast cancer screening by omitting any recommendation for mammography and clinical breast examination for women aged 40 to 49 years, while the American Cancer Society has reaffirmed its recommendation for these screening procedures in this age group. This article reviews the process and some of the evidence the American Cancer Society has relied upon in reaffirming its recommended guidelines for early breast cancer detection.
This study reports on the 20-year follow-up of the women diagnosed with breast cancer in the Breast Cancer Detection Demonstration Project (BCDDP) between 1973 and 1980. This project provided 5 years of screening with physical examination and two-view mammography for 280,000 volunteer women across the United States. Based on a 96% follow-up from 1993 to 1995 of the 4,051 women with breast cancer available for analysis, 2,658 (66%) were alive and 1,393 (34%) were dead. A high proportion of the cancers were detected by mammography alone, and 28.6% of all the cancers were smaller than 1.0 cm. Survival rates were calculated by life table method with deaths from breast cancer as the outcome. The adjusted survival rate for the entire group was 80.5%, and the observed survival rate was 61.7%. Adjusted and observed survival rates were 97.2% and 78.5%, respectively, for women with non-invasive cancers and 78.2% and 59.3%, respectively, for those with invasive cancers. Lymph node status and the size of the cancer at diagnosis were prognostic indicators of survival in the BCDDP Women with invasive cancers and negative lymph nodes had an 85.5% breast cancer survival rate and a 65.6% observed survival rate. Adjusted survival rates for women with invasive breast cancers were 90.2% for cancers smaller than 1 cm, 80.5%, for cancers 1.0 to 1.9 cm, 70.5% for cancers 2.0 to 4.9 cm, and 60.6% for cancers larger than 5 cm. Women 40 to 49 years of age demonstrated a greater survival with noninvasive or invasive cancers smaller than 5.0 cm compared with women 50 to 59 and 60 to 69 years of age at diagnosis. These results from the BCDDP are discussed in the context of the recent decline in breast cancer incidence and mortality in the United States.
A method to estimate site-specific cancer mortality rates using Surveillance, Epidemiology, and End Results (SEER) Program incidence and survival data is proposed, calculated, and validated. This measure, the life table-derived mortality rate (LTM), is the sum of the product of the probability of being alive at the beginning of an interval times the probability of dying of the cancer of interest during the interval times the annual age-adjusted incidence rate for each year that data have been collected. When the LTM is compared to death certificate mortality rates (DCM) for organ sites with no known misclassification problems, the LTM was within 10 percent of the death certificate rates for 13 of 14 organ sites. In the sites that have problems with the death certificate rates, there were major disagreements between the LTM and DCM. The LTM was systematically lower than the DCM for sites if there was overreporting on the death certificates, and the LTM was higher than the DCM for sites if there was underreporting. The limitations and applications of the LTM are detailed.
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