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PubMed1995

Survival analyses of atomic bomb survivors in Hiroshima Prefecture, Japan, 1968-1982--cancer mortality risk among early entrants.

We examined the mortality risk due to all causes of death and due to malignant neoplasms during 1968-82 among 204,209 atomic bomb survivors, including 49,215 early entrants. We used data compiled by the Research Institute for Radiation Biology and Medicine at Hiroshima University, which conducts mortality surveillance of these survivors in Hiroshima Prefecture, Japan. The purposes of this study were to investigate whether there was any relationship between exposure status and mortality risk among survivors, not altered by adjustment for confounding factors, and whether there were any differences among early entrants to the region within 2 km of the hypocenter after the bombing in mortality risk associated with date of entry and duration of stay. The mortality risk in directly exposed survivors decreased with distance from the hypocenter, even after adjustment for confounding factors. Entrants who entered the region on the day of the bombing had a significantly higher risk of mortality due to malignant neoplasm than those who entered thereafter, even after adjustment for the length of stay. The same results were obtained throughout the study period.

Adult↗
PubMed1995

Studies of cancer and radiation dose among atomic bomb survivors. The example of breast cancer.

A comprehensive program of medical follow-up of survivors of the atomic bombings of Hiroshima and Nagasaki, Japan, by the Radiation Effects Research Foundation (RERF) has produced quantitative estimates of cancer risk from exposure to ionizing radiation. For breast cancer in women, in particular, the strength of the radiation dose response and the generally low level of population risk in the absence of radiation exposure have led to a clear description of excess risk and its variation by age at exposure and over time following exposure. Comparisons of RERF data with data from medically irradiated populations have yielded additional information on the influence of population and underlying breast cancer rates on radiation-related risk. Epidemiological investigations of breast cancer cases and matched controls among atomic bomb survivors have clarified the role of reproductive history as a modifier of the carcinogenic effects of radiation exposure. Finally, a pattern of radiation-related risk by attained age among the survivors exposed during childhood or adolescence suggests the possible existence of a radiation-susceptible subgroup. The hypothetical existence of such a group is lent plausibility by the results of recent family studies suggesting that heritable mutations in certain genes are associated with familial aggregations of breast cancer. The recent isolation and cloning of one such gene, BRCA1, makes it likely that the hypothesis can be tested using molecular assays of archival and other tissue obtained from atomic bomb survivor cases and controls.

Adolescent↗
PubMed1995

Lung cancer mortality between 1950 and 1987 after exposure to fractionated moderate-dose-rate ionizing radiation in the Canadian fluoroscopy cohort study and a comparison with lung cancer mortality in the Atomic Bomb survivors study.

Current lung cancer risk estimates after exposure to low-linear energy transfer radiation such as X rays are based on studies of people exposed to such radiation at high dose rates, for example the atomic bomb survivors. Radiobiology and animal experiments suggest that risks from exposure at low to moderate dose rates, for example medical diagnostic procedures, may be over-estimated by such risk models, but data for humans to examine this issue are limited. In this paper we report on lung cancer mortality between 1950 and 1987 in a cohort of 64,172 Canadian tuberculosis patients, of whom 39% were exposed to highly fractionated multiple chest fluoroscopies leading to a mean lung radiation dose of 1.02 Sv received at moderate dose rates. These data have been used to estimate the excess relative risk per sievert of lung cancer mortality, and this is compared directly to estimates derived from 75,991 atomic bomb survivors. Based on 1,178 lung cancer deaths in the fluoroscopy study, there was no evidence of any positive association between risk and dose, with the relative risk at 1 Sv being 1.00 (95% confidence interval 0.94, 1.07), which contrasts with that based on the atomic bomb survivors, 1.60 (1.27, 1.99). The difference in effect between the two studies almost certainly did not arise by chance (P = 0.0001). This study provides strong support from data for humans for a substantial fractionation/dose-rate effect for low-linear energy transfer radiation and lung cancer risk.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Prevalence rate of thyroid diseases among autopsy cases of the atomic bomb survivors in Hiroshima, 1951-1985.

To examine the radiogenic risk of latent thyroid cancer, thyroid adenoma, colloid/adenomatous goiter and chronic thyroiditis, the data for 3821 subjects collected in the course of autopsies of atomic bomb survivors in Hiroshima from 1951 to 1985 by the Radiation Effects Research Foundation (RERF) were analyzed using a logistic model. About 80% of the autopsies were performed at RERF and the remainder at local hospitals. The frequencies of the above diseases were not associated with whether the underlying cause of death was cancer. However, note that our results may be influenced by potentially biasing factors associated with autopsy selection. The relative frequency of latent thyroid cancer (greatest dimension < or = 1.5 cm but detectable on a routine microscopic slide of the thyroid gland) increased as the radiation dose increased and was about 1.4-fold greater at 1 Gy than in the 0-Gy dose group. The relative occurrence of thyroid adenoma also increased as radiation dose increased, and was about 1.5-fold greater at 1 Gy than in the 0-Gy dose group. Sex, age at the time of the bombing or period of observation did not significantly modify the radiogenic risks for thyroid adenoma or latent thyroid cancer. No statistically significant association was found between radiation exposure and the rates of colloid/adenomatous goiter and chronic thyroiditis. The possible late effect of atomic bomb radiation on the frequency of benign thyroid diseases is discussed on the basis of these data.

Adenoma↗
PubMed1994

Cancer incidence in atomic bomb survivors. Part I: Use of the tumor registries in Hiroshima and Nagasaki for incidence studies.

More than 30 years ago, population-based tumor registries were established in Hiroshima and Nagasaki. This report, the first of a series of papers on cancer incidence, describes methodological aspects of the tumor registries and discusses issues of data quality in the context of the Life Span Study (LSS) cohort, the major atomic bomb survivor population. The tumor registries in Hiroshima and Nagasaki are characterized by active case ascertainment based on abstraction of medical records at area hospitals, augmented by tissue registries operational in the area and a number of clinical and pathological programs undertaken over the years among the atomic bomb survivors. Using conventional measures of quality, the Hiroshima and Nagasaki tumor registries have a death certificate-only (DCO) rate of less than 9%, a mortality/incidence (M/I) ratio of about 50%, and a histological verification (HV) rate in excess of 70%, which place these registries among the best in Japan and comparable to many established registries worldwide. All tumor registry data pertaining to the LSS population were assembled, reviewed and handled with special attention given to the quality and uniformity of data based on standardized procedures. Special studies and monitoring programs were also introduced to evaluate the quality of the tumor incidence data in the LSS. Analyses were performed to examine the quality of incidence data overall and across various substrata used for risk assessment such as age, time and radiation dose groups. No significant associations were found between radiation dose and data quality as measured by various indices. These findings warrant the use of the present tumor registry-based data for studies of cancer incidence in the atomic bomb survivors.

Adolescent↗
PubMed1994

Cancer incidence in atomic bomb survivors. Part II: Solid tumors, 1958-1987.

This report presents, for the first time, comprehensive data on the incidence of solid cancer and risk estimates for A-bomb survivors in the extended Life Span Study (LSS-E85) cohort. Among 79,972 individuals, 8613 first primary solid cancers were diagnosed between 1958 and 1987. As part of the standard registration process of the Hiroshima and Nagasaki tumor registries, cancer cases occurring among members of the LSS-E85 cohort were identified using a computer linkage system supplemented by manual searches. Special efforts were made to ensure complete case ascertainment, data quality and data consistency in the two cities. For all sites combined, 75% of the cancers were verified histologically, 6% were diagnosed by direct observation, 8% were based on a clinical diagnosis, and 12.6% were ascertained by death certificate only. A standard set of analyses was carried out for each of the organs and organ systems considered. Depending on the cancer site, Dosimetry System 1986 (DS86) organ or kerma doses were used for computing risk estimates. Analyses were based on a general excess relative risk model (the background rate times one plus the excess relative risk). Analyses carried out for each site involved fitting the background model with no dose effect, a linear dose-response model with no effect modifiers, a linear-quadratic dose-response model with no effect modifiers, and a series of linear dose-response models that included each of the covariates (sex, age at exposure, time since exposure, attained age and city) individually as effect modifiers. Because the tumor registries ascertain cancers in the registry catchment areas only, an adjustment was made for the effects of migration. In agreement with prior LSS findings, a statistically significant excess risk for all solid cancers was demonstrated [excess relative risk at 1 Sv (ERR1Sv) = 0.63; excess absolute risk (EAR) per 10(4) person-year sievert (PY Sv) = 29.7]. For cancers of the stomach (ERR1SV = 0.32), colon (ERR1SV = 0.72), lung (ERR1SV = 0.95), breast (ERR1SV = 1.59), ovary (ERR1SV = 0.99), urinary bladder (ERR1SV = 1.02) and thyroid (ERR1SV = 1.15), significant radiation associations were observed. There was some indication of an increase in tumors of the neural tissue (excluding the brain) among persons exposed to the bombs before age 20. For the first time, radiation has been associated with liver (ERR1SV = 0.49) and nonmelanoma skin (ERR1SV = 1.0) cancer incidence in the LSS cohort. The present analysis also strengthened earlier findings, based on a smaller number of cases, of an effect of A-bomb radiation on salivary gland cancer.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1993

Radiosensitivity of atomic bomb survivors as determined with a micronucleus assay.

If A-bomb survivors include a disproportionately large number of either radioresistant or radiosensitive persons, the surviving population would provide a biased estimate of the true risk of radiogenic cancer. To test this hypothesis, the in vitro X-ray sensitivities of peripheral blood lymphocytes obtained from 937 A-bomb survivors were measured with a cytokinesis-blocking micronucleus assay. Background frequencies (no irradiation in vitro) of micronuclei show a wide distribution. Frequencies in both males and females tend to increase with increasing donor age. Frequencies in females are significantly higher than those in males. Donor age decreases the sensitivity of lymphocytes to in vitro X-ray exposure at a rate of about 0.001 micronuclei per cell per year per gray. There is no effect of donors' sex on in vitro radiation sensitivity. Atomic bomb radiation and cigarette smoking had no significant effect on background and X-ray-induced micronuclei frequencies. Thus there is no difference in radiosensitivity of peripheral blood lymphocytes between proximally and distally exposed survivors.

Age Factors↗
PubMed1996

Somatic cell mutations at the glycophorin A locus in erythrocytes of atomic bomb survivors: implications for radiation carcinogenesis.

To clarify the relationship between somatic cell mutations and radiation exposure, the frequency of hemizygous mutant erythrocytes at the glycophorin A (GPA) locus was measured by flow cytometry for 1,226 heterozygous atomic bomb (A-bomb) survivors in Hiroshima and Nagasaki. For statistical analysis, both GPA mutant frequency and radiation dose were log-transformed to normalize skewed distributions of these variables. The GPA mutant frequency increased slightly but significantly with age at testing and with the number of cigarettes smoked. Also, mutant frequency was significantly higher in males than in females even with adjustment for smoking and was higher in Hiroshima than in Nagasaki. These characteristics of background GPA mutant frequency are qualitatively similar to those of background solid cancer incidence or mortality obtained from previous epidemiological studies of survivors. An analysis of the mutant frequency dose response using a descriptive model showed that the doubling dose is about 1.20 Sv [95% confidence interval (CI): 0.95-1.56], whereas the minimum dose for detecting a significant increase in mutant frequency is about 0.24 Sv (95% CI: 0.041-0.51). No significant effects of sex, city or age at the time of exposure on the dose response were detected. Interestingly, the doubling dose of the GPA mutant frequency was similar to that of solid cancer incidence in A-bomb survivors. This observation is in line with the hypothesis that radiation-induced somatic cell mutations are the major cause of excess cancer risk after radiation exposure. Furthermore, the dose response was significantly higher in persons previously or subsequently diagnosed with cancer than in cancer-free individuals. This may suggest an earlier onset of cancer due to elevated mutant frequency or a higher radiation sensitivity in the cancer group, although the possibility of dosimetry errors should be considered. The findings obtained in the present study suggest that the GPA mutant frequency may reflect the cancer risk among people exposed to radiation.

Adult↗
PubMed1996

Prevalence of skin neoplasms among the atomic bomb survivors.

About 7,000 atomic bomb (A-bomb) survivors from Hiroshima and Nagasaki who participate in the Radiation Effects Research Foundation (RERF) Adult Health Study (AHS) were examined to define the relationship between skin neoplasms and exposure to ionizing radiation. Careful clinical inspection of the skin was undertaken to detect not only skin cancer but precancerous lesions such as senile keratosis. Five cases of basal cell carcinoma, five cases of senile keratosis and one case of Bowen's disease were confirmed histologically among 5955 A-bomb survivors for whom Dosimetry System 1986 (DS86) dose estimates are available. The relationship between the combined prevalence of skin cancer and precancerous lesions and DS86 dose was examined together with other factors that might affect skin neoplasms including occupational exposure to ultraviolet (UV) rays, age, sex and city. The prevalence of basal cell carcinoma and senile keratosis increased as the DS86 dose increased. The prevalence of skin cancer and senile keratosis among persons engaged in work involving frequent exposure to UV rays was higher than among those who were not engaged in such work. Sex and city were not significantly related to those skin diseases. Odds ratios of skin neoplasm for a 1-Gy dose, occupational exposure to UV rays and age at time of examination (in 10-year increments) are 1.7, 5.9 and 1.9, respectively.

Adult↗
PubMed1996

Mortality study of atomic-bomb survivors: implications for assessment of radiation accidents.

To determine the possible late effects of atomic-bomb radiation, the Life Span Study (LSS) cohort of about 120,000 individuals, including 93,000 atomic bomb survivors and 27,000 non-exposed controls, was established by the Radiation Effects Research Foundation (RERF). Mortality in this cohort has been under study since 1950. Deaths are routinely identified through the family registry system and ascertainment is virtually complete. Cancer incidence data for the LSS cohort are also available from the Hiroshima and Nagasaki population-based tumour registry established in 1958. The central finding of the LSS is an increase in cancer risk. Besides the well-known increase in leukaemia, increases in solid cancer such as cancers of the lung, breast, stomach and thyroid have also been demonstrated. Radiation-induced leukaemia occurred 2 to 3 years after exposure, reached its peak within 6 to 8 years after the bombing, and has since declined steadily. However, this has not been true of solid cancer. Radiation-induced solid cancer begins to appear at later ages than such cancer is normally prone to develop, and continues to increase proportionally with the increase in mortality or incidence in the control group as it ages. Survivors who were exposed in the first or second decade of life have just entered the cancer-prone age and have so far exhibited a high relative risk in association with radiation dose. Whether the elevated risk will continue or will fail with time is not yet clear. It is important to continue long-term follow-up of this cohort to document the changes with time since exposure. Beyond cancer risk, increased risk of non-cancer mortality is also suggested, although it is not conclusive.

Adult↗
PubMed1998

Injuries and illnesses in working dogs used during the disaster response after the bombing in Oklahoma City.

OBJECTIVES: To determine characteristics of working dogs used during the disaster response after the bombing in Oklahoma City and risk factors for injuries and illnesses of those dogs, and to document recommendations for future disaster responses. DESIGN: Survey. STUDY POPULATION: Information for 74 working dogs used at the bombing site. PROCEDURES: Dog handlers were identified and asked to complete a questionnaire. Questions were asked about the training and use of each dog, use of paw protection, injuries and illnesses incurred, possible effects after completion of duty at Oklahoma City, and handler's experience. RESULTS: Data were obtained for all 74 dogs used at the site. Handlers of 69 of 74 (93%) dogs responded. The dogs had been extensively trained and were used 491 dog-days at the site, with 46 dogs used in search, 14 in patrol, 12 in explosive-detection duty, and 2 in search/patrol. Fifteen (22%) dogs became ill. Nineteen (28%) dogs incurred 20 injuries. Footpad injuries constituted 18 of the injuries. Only 16 of 69 (23%) dogs were provided with paw protection. Dogs were more likely to be injured when they were used in a search capacity, were used during the first 2 days after the bombing, were German Shepherd Dogs, or were older. CLINICAL IMPLICATIONS: Although working in a high-risk environment, injuries to dogs were few, and most were minor. Specific recommendations could facilitate use of dogs in disaster situations and improve safety for those dogs.

Animals↗
PubMed1999

Comparison of breast cancer incidence in the Massachusetts tuberculosis fluoroscopy cohort and in the Japanese atomic bomb survivors.

Breast cancer has occurred in excess among women exposed briefly to atomic bomb radiation and among those exposed repeatedly over many years to medical radiation for tuberculosis (TB). The excess relative risk of breast cancer incidence in the Japanese atomic bomb survivors, however, is significantly higher (two-sided P = 0.04) than that in the Massachusetts TB fluoroscopy patients. The best estimate of the ratio between the excess relative risk coefficients for the Japanese and Massachusetts cohorts is 2.11 (95% CI 1.05, 4.95). However, this higher relative excess risk is attributable to the lower baseline risk of breast cancer among Japanese women compared with the Massachusetts women, and the excess absolute breast cancer risks in the two data sets are statistically indistinguishable (two-sided P = 0.32). The best estimate of the ratio between the excess absolute risk coefficients among Japanese and Massachusetts women is 0.73 (95% CI 0.41, 1.44). After childhood exposures, an early onset of radiation-induced breast cancer was seen among Japanese atomic bomb survivors but not among the Massachusetts women. There are some indications (two-sided P = 0.04) of differences in the patterns of risk over time since exposure between these groups exposed in childhood. However, in general there are no marked differences between the Massachusetts and Japanese data sets in the age and time distribution of risk of radiation-induced breast cancer. These data provide little evidence for a reduction of breast cancer risk after fractionated irradiation.

Adolescent↗
PubMed1999

Psychiatric disorders among survivors of the Oklahoma City bombing.

CONTEXT: Disasters expose unselected populations to traumatic events and can be used to study the mental health effects. The Oklahoma City, Okla, bombing is particularly significant for the study of mental health sequelae of trauma because its extreme magnitude and scope have been predicted to render profound psychiatric effects on survivors. OBJECTIVE: To measure the psychiatric impact of the bombing of the Alfred P. Murrah Federal Building in Oklahoma City on survivors of the direct blast, specifically examining rates of posttraumatic stress disorder (PTSD), diagnostic comorbidity, functional impairment, and predictors of postdisaster psychopathology. DESIGN, SETTING, AND PARTICIPANTS: Of 255 eligible adult survivors selected from a confidential registry, 182 (71%) were assessed systematically by interviews approximately 6 months after the disaster, between August and December 1995. MAIN OUTCOME MEASURES: Diagnosis of 8 psychiatric disorders, demographic data, level of functioning, treatment, exposure to the event, involvement of family and friends, and physical injuries, as ascertained by the Diagnostic Interview Schedule/Disaster Supplement. RESULTS: Forty-five percent of the subjects had a postdisaster psychiatric disorder and 34.3% had PTSD. Predictors included disaster exposure, female sex (for any postdisaster diagnosis, 55% vs 34% for men; chi2 = 8.27; P=.004), and predisaster psychiatric disorder (for PTSD, 45% vs 26% for those without predisaster disorder; chi2 = 6.86; P=.009). Onset of PTSD was swift, with 76% reporting same-day onset. The relatively uncommon avoidance and numbing symptoms virtually dictated the diagnosis of PTSD (94% meeting avoidance and numbing criteria had full PTSD diagnosis) and were further associated with psychiatric comorbidity, functional impairment, and treatment received. Intrusive reexperience and hyperarousal symptoms were nearly universal, but by themselves were generally unassociated with other psychopathology or impairment in functioning. CONCLUSIONS: Our data suggest that a focus on avoidance and numbing symptoms could have provided an effective screening procedure for PTSD and could have identified most psychiatric cases early in the acute postdisaster period. Psychiatric comorbidity further identified those with functional disability and treatment need. The nearly universal yet distressing intrusive reexperience and hyperarousal symptoms in the majority of nonpsychiatrically ill persons may be addressed by nonmedical interventions of reassurance and support.

Adaptation, Psychological↗
PubMed1997

Injuries to rescue workers following the Oklahoma City bombing.

The objective of this study was to identify and describe physical injuries to rescue workers in the aftermath of the Oklahoma City bombing. Data were obtained from medical records from 16 hospital emergency departments and specialty clinics in the Oklahoma City area, and reported visits to medical providers at the bombing site. Participants were rescue personnel from the Oklahoma City Fire Department, the mutual aid fire stations in the Oklahoma City area, the Federal Emergency Management Agency's Urban Search and Rescue teams, and military personnel stationed near Oklahoma City. All participants were involved in the rescue and recovery operation. The two main outcome measures were (1) the number, types, and rates of injuries; and (2) comparisons of case-finding methods, including medical chart review and telephone interview. The most common injuries were strains and sprains (21.4%), foreign bodies in eyes (14.5%), and laceration/crush/puncture wounds (18.4%). Of the four case-finding mechanisms, telephone interviews following the event identified the largest number of cases (84.5%). Most injuries were minor; some injuries such as chemical burns were preventable. The potential utility of other data collection mechanisms is considered.

Eye Foreign Bodies↗
PubMed1996

Psychological response to the Oklahoma City bombing.

The bombing of the Alfred P. Murrah Federal Office Building in Oklahoma City was the most devastating terrorist activity that has occurred in America. Prevention of revictimization of persons seriously affected by the bombing was central to the planned response to this tragedy. Coordination and collaboration among local, state, and national agencies promoted effective clinical services provision, research facilitation, and prevention of revictimization. Information gathered from this cooperative effort will contribute to the effort to minimize the potential for such tragedies in the future as well as help to develop prevention and intervention strategies to reduce the effects when the next such disaster occurs.

Adaptation, Psychological↗
PubMed1981

Cancer of the head and neck in atomic bomb survivors: Hiroshima and Nagasaki, 1957-1976.

A search was conducted in Hiroshima and Nagasaki for all cases of cancer of the lip, nose and nasal cavity, accessory sinuses, larynx, and the oral cavity and pharynx with their subdivisions occurring during the period 1957-1976 among a large, fixed cohort of atomic bomb survivors. A total of 232 cases were identified, of which 154 (66.4%) were histologically confirmed (definite cases). Among definite cases, cancer of the epiglottis and larynx predominated (31.2%), followed by accessory sinus (24.7%) and tongue (18.8%). Of the 154 definite cases, 141 (91.6%) were squamous-cell carcinomas. Only two sarcomas were identified, neither of which was attributable to radiation exposure. Analysis of both total and definite cases, by both total group and major anatomic site, failed to reveal definite evidence of a radiation relationship. Although a suggestive relationship to radiation dose was found for accessory sinus cancers (P = 0.06) among the definite cases, inconsistencies in the data do not permit the conclusion that the incidence of tumors in this group increased as a result of atomic bomb radiation exposure. The medical literature concerning post-irradiation head and neck tumors is briefly reviewed.

Carcinoma, Squamous Cell↗
PubMed1983

Salivary gland tumors in atomic bomb survivors, hiroshima, japan. II. Pathologic study and supplementary epidemiologic observations.

A pathological investigation was undertaken in Hiroshima on cases seen between 1945 and 1971 to determine the relationship between salivary gland tumors and exposure to atomic (A) bomb radiation. Of the 208 cases of histologically confirmed salivary gland tumors, 62 were A-bomb survivors and 146 were nonexposed. The relative risk based on the rate in the nonexposed for malignant tumors of salivary glands among the exposed in Hiroshima Prefecture was 11.0, while that of the submaxillary gland was 13.8 and that of the parotid gland was 9.8. They were all highly significant by X2 test (P less than 0.001). The latent period of malignant salivary gland tumors was shorter in the exposed than in the nonexposed. Four cases of benign salivary gland tumor, all being benign mixed tumors of the parotid gland, were observed in children whose parents had been exposed. The incidence of mixed tumors of the salivary gland among the exposed in Hiroshima City was 2.0 times higher than that among the nonexposed and showed a tendency to increase with proximity to the hypocenter (P less than 0.01).

Adenoma, Pleomorphic↗
PubMed1993

Proliferative and nonproliferative breast disease in atomic bomb survivors. Results of a histopathologic review of autopsy breast tissue.

BACKGROUND: The risk of female breast cancer in association with radiation dose is well established, on the basis of follow-up studies of the atomic bomb survivors and other exposed populations. This association is especially strong for women exposed before 20 years of age and appears to be much weaker among women exposed after 40 years of age. METHODS: Breast tissue samples from 88 high-dose and 225 low-dose autopsy cases from the Radiation Effects Research Foundation Life Span Study sample were examined in detail to determine whether nonproliferative and proliferative breast lesions are associated with radiation dose. RESULTS: Prevalence of proliferative disease in general and atypical hyperplasia in particular were positively associated with radiation dose. The associations were strongest for subjects who were between 40 and 49 years of age at the time of the bombing. CONCLUSIONS: It is hypothesized that the strongest association in women 40 to 49 years of age may be related to the age dependence of radiation-induced breast cancer, in that potential cancers induced in this age group by radiation exposure may receive too little hormonal promotion to progress to frank cancers.

Adolescent↗