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Biomedical subjects

R Hoover

Publications and source records attributed to R Hoover.

At least 109 records · Page 6Linked to original sources

Adhesion of normal and sickle erythrocytes to endothelial monolayer cultures.

Experiments were carried out to test the hypothesis that the differences between the surfaces of erythrocytes from normal and sickle cell patients are reflected in the degree of attachment to the capillary lining. An assay was used that measured the number of 51Cr-labeled erythrocytes (normal or sickle) attaching to a monolayer of endothelium cultured from calf aortas. Under these conditions, erythrocytes from sickle cell patients adhered better to the endothelium than did those from normal patients. The results suggested that the enhanced adhesion of the sickle cells to the endothelium may be partially responsible for the increased blockage of capillaries that produce the symptoms in sickle cell anemia.

Anemia, Sickle Cell↗

Lung cancer after employment in shipyards during World War II.

A case-control study, undertaken to identify reasons for the exceptionally high rate of lung cancer among male residents of coastal Georgia, revealed a significantly increased risk associated with employment in area shipyards during World War II. The summary relative-risk estimate, adjusted for smoking, other occupations, age, race and county of residence was 1.6 (95 per cent confidence limits = 1.1 to 2.3). A synergistic relation was found between shipyard employment and cigarette smoking. These findings suggest that asbestos and possible other shipyard exposures during wartime employment account for part of the excess mortality from lung cancer in certain coastal areas of the United States.

Aged↗

Second primary neoplasms following ovarian cancer.

Follow-up surveys of patients with ovarian cancer revealed an increased risk of second primary cancers of the uterine corpus, colon, bladder, breast, and hematopoietic system. The excess risk or uterine corpus cancer was independent of therapy. The risk of colon cancer was increased in all treatment groups but was especially high among patients receiving radiation or chemotherapy. The predisposition to other neoplasms was limited to certain treatment groups: bladder cancer to irradiation, leukemia to chemotherapy, and lymphoma to either modality. The pattern of second neoplasms following ovarian cancer appears to be influenced by therapy as well as by common etiologic factors.

Alkylating Agents↗

Oral contraceptive use: association with frequency of hospitalization and chronic disease risk indicators.

A questionnaire was mailed to 97,364 married women, aged 26--50, resident in Greater Boston in 1970, requesting information on lifetime oral contraceptive (OC) use, reproductive history, education, and hospitalization experience in 1969; 65,843 women responded. In 1973 a second questionnaire was mailed to 37,292 of these women, including all OC users and an equal number of non-users matched on age, parity, education, and town of residence. This questionnaire related to use of OCs, other female hormones, and the menopause. OC use was most strongly related to age, with a sixfold increase in use from the oldest women (of whom 10 per cent had used OCs at some time) to the youngest. Use was directly related to education and mobility and inversely related to parity. Reasons for beginning and ceasing use differed for women of different ages and educational attainment. Thus, use of OCs varies with social and reproductive characteristics that are risk indicators for many diseases. OC use was associated with increased risk of hospitalization for thromboembolic disease (risk ratio = 1.5, 95 per cent confidence limits 1.2, 3.2) and for mental illness, hyperthyroidism, hypertension, and cancer of the cervix. OC users were hospitalized for many non-life threatening conditions 20 to 40 per cent more frequently than were non-users.

Adult↗

Increased risk of lymphoma in sicca syndrome.

The risk of cancer was ascertained in 136 women with sicca syndrome followed at the National Institutes of Health (NIH). Seven patients developed non-Hodgkin's lymphoma from 6 months to 13 years after their first admission to NIH. This was 43.8 times (P less than 0.01) the incidence expected from the rates of cancer prevailing among women of the same age range in the general population during this time. In addition, three cases of Waldenström's macroglobulinemia occurred in this study group. Eight patients developed cancers other than lymphoma, similar to the number expected based on the rates prevailing in the general population. Patients with a history of parotid enlargement, splenomegaly, and lymphadenopahy had an increased risk of lymphoma. These clinical conditions did not appear to be early manifestations of undiagnosed lymphoma but rather seemed to identify a subgroup of patients with sicca syndrome with marked lymphoid reactivity, who had a particularly high risk of subsequently developing lymphoma.

Adult↗

Associations of cancer mortality with halomethanes in drinking water.

Associations between site- and sex-specific county cancer mortality rates and levels of trihalomethanes (THM's) in drinking water were examined after adjustment of rates for the influence of multiple socioeconomic, industrial, and demographic factors. U.S. counties with sampled supplies were grouped by percent of the county population receiving water from the supply, as well as by region of the country. For two sites (bladder and lung), county rates were also adjusted for the activity level in specific high-risk industries. Positive correlations with THM levels were observed for several cancers, including bladder and brain cancers in both sexes, and non-Hodgkin's lymphoma and kidney cancer in males. Stomach cancer in females showed a negative association. Bladder cancer mortality rates showed the strongest and most consistent association with a THM exposure index, after control for differences in social class, ethnic group, urban versus rural residence, region of the United States, and industrialization of the county. These ecologic associations suggested that further evaluation in analytic investigations is warranted.

Brain Neoplasms↗

Stilboestrol (diethylstilbestrol) and the risk of ovarian cancer.

A follow-up survey of 908 women who had received 'Premarin' (conjugated equine oestrogen) for menopausal symptoms revealed 8 cases of ovarian cancer. This risk was 2 to 3 times greater than expected. The risk increased with the strength of premarin tablet usually taken, but not with the duration of use or total dose ingested. The excess risk of ovarian cancer in this group occurred primarily among 21 women who had also used stilboestrol (diethylstilbestrol). The results of this small trial are consistent with the increasing incidence of ovarian cancer in post-menopausal women in the U.S.A., and with the occurrence of stilboestrol-induced ovarian neoplasms in dogs.

Cocarcinogenesis↗

Acute leukemia after alkylating-agent therapy of ovarian cancer.

To estimate the leukemogenic potential of alkylating agents, we surveyed 70 institutions using these drugs for the frequency of second cancers in patients with advanced ovarian cancer. Thirteen cases of acute nonlymphocytic leukemia occurred among 5455 patients, as compared to 0.62 cases expected (relative risk = 21.0). All 13 had received alkylating agents. Nine also received radiotherapy. The relative risk for patients given chemotherapy was 36.1 and rose to 171.4 for those surviving for two years (rate = 13.75 per 1000 patients per year). To evaluate the role of therapy versus underlying disease, a historical control of 13,309 patients with ovarian cancer in the National Cancer Institute's End Results Program was analyzed. No excess of leukemia was noted in this group, even among 6596 women receiving radiation. The excess of acute nonlymphocytic leukemia, therefore, appears attribute to alkylating agents, although the effect may be enhanced by exposure to radiation, as previously suggested for Hodgkin's disease.

Acute Disease↗

Nasopharyngeal cancer among young people in the United States: racial variations by cell type.

U. S. mortality and incidence statistics for nasopharyngeal cancer showed a fourfold excess risk of sarcomas in white children under age 10, and a fourfold to sevenfold excess of carcinomas in teen-age blacks. Mortality from nasopharyngeal carcinomas in young people was greater in the South than in the North, with the excess mortality in blacks linked to rural residence and low socioeconomic status. These and other characteristics of nasopharyngeal carcinoma in young persons suggested that environmental (perhaps infectious) agents are involved in this age group. These patterns contrasted with nasopharyngeal carcinomas developing after age 25, when the rates predominated in Chinese Americans. Nasopharyngeal cancer in the United States had three age peaks, with racial and epidemiologic distinctions that seemed to reflect different etiologies.

Adolescent↗

Immunosurveillance and cancer: epidemiologic observations.

To evaluate the immunologic surveillance theory of cancer, we reviewed the epidemiologic observations that have been made on cancer risk among population groups with immune deficiency. Lymphoproliferative neoplasms predominate in various groups, most notably renal transplant recipients treated with immunosuppressive agents and patients with primary immunodeficiency syndromes. In some immune disorders, specific forms of nonlymphoid neoplasia seem to occur excessively, although the patterns are not clear-cut or consistent. The available epidemiologic evidence fails to support the concept that immunosurveillance mechanisms are generally involved in carcinogenesis but does provide clues to immunologic processes that may predispose to particular neoplasms.

Adult↗

Menopausal estrogens and breast cancer.

1891 women given conjugated estrogens for the menopause were followed for 12 years (mean) for incidence of breast cancer. Overall, 49 cases were observed; 39.1 were expected on the basis of rates in the general population (relative risk = 1.3, P = 0.06). The relative risk increased with follow-up duration, progressing to 2.0 after 15 years (13/6.6, P = 0.01). The excess risk after 10 years was not due simply to prolonged estrogen use, since there was no clear dose-response relation to accumulated years of use. However, higher risk accrued to women using higher-dose tablets and those taking the medication on an other than daily basis. In addition, after 10 years of follow-up observation, two factors related to low risk of breast cancer, multiparity and oophorectomy, were no longer so related. Finally, estrogen use was related to an especially high risk of breast cancer among women in whom benign disease developed after they had started the drug.

Aged↗

Cancer of the uterine corpus after hormonal treatment for breast cancer.

Among 45853 women in whom breast cancer was diagnosed after age forty-nine, from the series of the End Results Program of the National Cancer Institute, cancer of the uterine corpus subsequently developed in 203. The risk was greater among those women receiving hormones than in other treatment groups, and tended to rise with increasing interval from first treatment. One method of estimating an expected value indicated that the excess risk of corpus cancer in breast-cancer patients was restricted to those treated with hormones. Given the time period under study, it may be assumed that the hormones were primarily non-steroidal oestrogens.

Age Factors↗

Oral contraceptives and reduced risk of benign breast diseases.

In 1970 a questionnaire on oral-contraceptive use was mailed to 97,254 married women 25 to 49 years of age in Greater Boston. Sixty-nine per cent responded. During the subsequent 30 months, 1072 of the women were hospitalized for breast diseases. Hospitalization rates for fibrocystic disease were similar for non-users of oral contraceptives and users of one to 12 months' duration. However, users for 13 months to 24 months and 25 or more months had rates only 70 and 35 per cent, respectively, of those of non-users. Detailed analysis of these results, and their similarity to findings in previous studies, suggest that the association is causal--use of oral contraceptives appears to lower risk of fibrocystic breast disease. A similar association was seen for fibroadenoma. Rates of breast cancer were lower for users than for non-users, but this finding was neither related to duration of use nor statistically significant.

Adenofibroma↗

Cancer by county: new resource for etiologic clues.

Mapping of U. S. cancer mortality by county has revealed patterns of etiologic significance. The patterns for bladder cancer in males point to industrial determinants: some are known (chemical manufacturing) but others (automobile and machinery manufacturing) represent new leads for epidemiologic study. By contrast, the geographic clusters of high rates of stomach cancer in both sexes are consistent with ethnic susceptibility.

Environment↗

Prognosis of black children with acute lymphocytic leukemia.

To assess the racial differences in survival of children with acute lymphocytic leukemia, we analyzed data for 1,675 white and 126 black children, diagnosed from 1955 to 1969. Blacks had a significantly shorter median survival and lower one-year and three-year survival rates than whites. There was substantial variation in racial differences by age. In addition, much of the variation between races seemed to be due to socioeconimic factors rather than strictly racial ones. Identification of the specific factors responsible for the poorer survival of children from lower social classes is sorely needed.

Adolescent↗