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Biomedical subjects

C E Land

Publications and source records attributed to C E Land.

54 records · Page 3Linked to original sources
PubMed1980

Estimating cancer risks from low doses of ionizing radiation.

Disagreements about the somatic risks from low doses of ionizing radiation stem from two difficulties fundamental to the logic of inference from observational data. First, precise direct estimation of small risks requires impracticably large samples. Second, precise estimates of low-dose risks based largely on high-dose data, for which the sample size requirements are more easily satisfied, must depend heavily on assumptions about the shape of the dose-response curve, even when only a few of the parameters of the theoretical form of the curve are unknown.

Adult↗
PubMed1980

Low-dose radiation--a cause of breast cancer?

It is likely that the breast is the organ most sensitive to radiation carcinogenesis in postpubertal women. Studies of different exposed populations have yielded remarkably consistent results, in spite of wide differences in underlying breast cancer rates and conditions of exposure. Excess risk is approximately proportional to dose, and is relatively independent of ionization density and fractionization of dose. This implies that the risk associated with low-dose exposures to ionizing radiation can be estimated with some confidence from higher-dose data. Excess risk is heavily dependent on age at exposure but relatively independent of population differences in normal risk. The temporal patterns after exposure of both radiation-induced and naturally occurring breast cancer are similar, suggesting a strong influence of factors other than radiation on radiation-induced breast cancer. Uncertainties remain about risks from exposures before puberty and after menopause.

Adolescent↗
PubMed1980

Breast cancer risk from low-dose exposures to ionizing radiation: results of parallel analysis of three exposed populations of women.

Breast cancer incidence data were analyzed from three populations of women exposed to ionizing radiation: survivors of the Hiroshima and Nagasaki atomic bombs, patients in Massachusetts tuberculosis sanitoria who were exposed to multiple chest fluoroscopies, and patients treated by X-rays for acute postpartum mastitis in Rochester, New York. Parallel analyses by radiation dose, age at exposure, and time after exposure suggested that risk of radiation-induced cancer increased approximately linearly with increasing dose and was heavily dependent on age at exposure; however, the risk was otherwise remarkably similar among the three population, at least for age 10-40 years at exposure, and followed the same temporal pattern of occurrence as did breast cancer incidence in nonexposed women of similar ages.

Adolescent↗
PubMed1979

Risk of breast cancer following low-dose radiation exposure.

Risk of breast cancer following radiation exposure was studied, based on surveys of tuberculosis patients who had multiple fluoroscopic examinations of the chest, mastitis patients given radiotherapy, and atomic bomb survivors. Analysis suggests that the risk is greatest for persons exposed as adolescents, although exposure at all ages carries some risk. The dose-response relationship was consistent with linearity in all studies. Direct evidence of radiation risk at doses under 0.5 Gy (50 rad) is apparent among A-bomb survivors. Fractionation does not appear to diminish risk, nor does time since exposure (even after 45 years of observation). The interval between exposure and the clinical appearance of radiogenic breast cancer may be mediated by hormonal or other age-related factors but is unrelated to dose. Age-specific absolute risk estimates for all studies are remarkably similar. The best estimate of risk among American women exposed after age 20 is 6.6 excess cancers/10(4) WY-G-Y (10(6) WY-rad).

Adolescent↗
PubMed1977

Epidemiologic studies of coronary heart disease and stroke in Japanese men living in Japan, Hawaii and California. Coronary heart disease risk factors in Japan and Hawaii.

Various risk factors were evaluated to explain a significantly greater incidence of coronary heart disease in men of Japanese ancestry resident in Hawaii compared with men resident in Japan. The independent predictors of incidence of coronary heart disease in both Japan and Hawaii were systolic blood pressure, serum cholesterol, relative weight and age. These factors appeared to influence incidence similarly in both areas because in each case the correlation coefficients for Japan and Hawaii did not differ significantly. The hypothesis that the greater incidence in Hawaii could be attributed to differences in levels of these risk factors was tested with the Walker-Duncan method. The four variable multiple logistic function describing the probability of coronary heart disease in Japan was applied to the cohort characteristics observed in Hawaii. The estimated incidence thus obtained was not significantly different from that actually observed in the men resident in Hawaii. Therefore the increased coronary risk profile in Hawaii compared with Japan can account for the greater incidence of coronary heart disease in the former. Current cigarette smoking was significantly related to the risk of coronary heart disease in Hawaii but not in Japan. This difference requires further investigation.

Age Factors↗
PubMed1976

Accuracy of diagnosis of cancer among autopsy cases: JNIH--ABCC population for Hiroshima and Nagasaki.

The accuracy of death certificate diagnoses of cancer in the fixed population of about 100,000 samples in Hiroshima and Nagasaki was determined for the period 1961 approximately 1970 by comparison with autopsy findings. In general, when the death certificate listed cancer as a cause of death it was found at autopsy in a high proportion of cases. However, cancer was not always reported on death certificates, indicating that cancer occurs more frequently than recorded by official mortality statistics. Older persons, persons who die at home, and persons with certain cancers are more likely not to have cancer named on their death certificates. It is estimated that in the 10,749 deaths occurring at home or in hospital, there were 32% more deaths due to cancer than certified on death certificates (3,095 vs. 2,345) and for persons aged 70 or more dying at home it is estimated there were 55% more stomach cancer (269 estimated vs. 174 listed) and 244% more lung cancer (141 estimated vs. 41 listed) than were certified on death certificates. The death certificate is not a good source of information for cancer of the cervix because many cases of this disease reported on death certificates as cancer of the uterus. This practice needs to be taken into account in the use of mortality data for cervical cancer in Japan.

Age Factors↗
PubMed1975

Lung cancer at autopsy in A-bomd survivors and controls, Hiroshima and Nagasaki, 1961-1970. II. Smoking, occupation, and A-bomb exposure.

The apparent effect of ionizing radiation on lung cancer in A-bomb survivors has not been large enough to still doubts as to its validity. It has seemed essential to determine whether the apparent radiation effect could have resulted from a confounding of heavy smoking and high radiation dose, or if the occupational exposure of high-dose subjects with lung cancer was suggestive of the influence of environmental hazards other than radiation. The available series consists of 204 subjects with lung cancer verified by autopsy, 61 of whom were low-dose (less than 1 rad) and 13 high-dose (200 + rads) subjects. No evidence could be found that the influence of either smoking or occupational exposure upon lung cancer was exerted so as to suggest that the apparent radiation effect is other than real. The study also provides additional evidence of the relationship between lung cancer and smoking in Japanese.

Aged↗
PubMedDate not supplied

p53 mutations in lung cancers from non-smoking atomic-bomb survivors.

Tobacco smoke contains many carcinogens and has been linked with the development of lung cancer. We sequenced the conserved regions of the p53 tumour suppressor gene in lung cancers from 17 non-smokers from Hiroshima, Japan; 9 were atomic-bomb survivors. The mutations were predominantly transitions (all G:C to A:T); there were no G:C to T:A transversions. By contrast, lung cancers from 77 Japanese smokers have a predominance of G:C to T:A transversions in which the guanine residues occur on the non-transcribed DNA strand. These findings further implicate tobacco smoke carcinogens in the molecular pathogenesis of lung cancer.

Adult↗
PubMedDate not supplied

A unique morphology of Epstein-Barr virus-related early gastric carcinoma.

Epstein-Barr virus (EBV) involvement in gastric cancer is demonstrated by uniform presence of viral RNA in carcinoma cells as detected by EBV-encoded small RNA in situ hybridization, monoclonal proliferation of EBV-infected carcinoma cells, and elevated antibodies. Our review of selected early gastric cancers found that 46 of 49 EBV-positive lesions (94%) but only four of 97 EBV-negative lesions (4%) conformed to a unique morphology, in which carcinoma cells formed lace patterns of branching and/or anastomosing structures with lymphocytic infiltration in and around the carcinoma nests in the mucosa. We conclude that EBV-related gastric carcinoma has a distinct and characteristic morphology in the early stage of development, and this lace pattern is a biomarker of EBV involvement in early gastric cancer.

Adenocarcinoma↗