Cancer in Japanese exposed as children to atomic bombs

A possible association between ionizing radiation and pituitary adenoma: a descriptive study

BACKGROUND

Despite the recognition of ionizing radiation as a causal risk factor for a variety of solid tumors (including brain tumors), to date, such an association with pituitary adenoma (PA) has not been demonstrated.

METHODS

To evaluate a possible association between past exposure to radiation and the occurrence of PA, the authors reviewed about 4900 medical records of patients who had been irradiated in childhood for tinea capitis. An additional search for patients was performed using the Israel Cancer Registry. The average radiation dose to the pituitary gland was estimated as 0.56 grays, and, for all patients, a meticulous validation of the irradiation was performed.

RESULTS

A group of 16 patients who developed symptomatic PA after childhood exposure to radiotherapy were identified. Overall, the clinical and demographic characteristics of these patients were similar to other series reported in the literature. There was an apparently high rate of second primary tumors (25%), all of them in the irradiated area, diagnosed among this group. The methodologic issues that limit the demonstration of a possible association between radiation and PA and the epidemiologic and experimental findings in the literature are discussed.

CONCLUSIONS

In view of the ample amount of evidence identifying low-dose ionizing radiation as a risk factor for a number of intracranial tumors as well as for tumors arising in endocrine organs, a radiation immunity of the pituitary gland is difficult to accept. Hence, the authors suggest that this series should be considered as preliminary observation that supports the role of ionizing radiation in the development of this tumor.

Protracted and Variable Latency of Acute Lymphoblastic Leukemia AfterTEL-AML1 Gene Fusion In Utero

We report a pair of identical twins with concordant acute lymphoblastic leukemia (ALL). Unusually, their diagnoses were spaced 9 years apart at ages 5 and 14. Leukemic cells in both twins had aTEL-AML1 rearrangement, which was characterized at the DNA level by an adaptation of a long distance polymerase chain reaction (PCR) method. The genomic fusion sequence was identical in the two leukemias, indicative of a single cell origin in one fetus, in utero. At the time twin 1 was diagnosed (aged 5 years), the bone marrow of twin 2 was hematologically normal. However, retrospective scrutiny of the DNA from an archived slide with clonotypic TEL-AML1 primers showed that the presumptive preleukemic clone was present and disseminated 9 years before a clinical diagnosis. These data provide novel insight into the natural history of childhood leukemia and suggest that consequent to a prenatal initiation of a leukemic clone, most probably by TEL-AML fusion itself, the latency of ALL can be both extremely variable and protracted. This, in turn, is likely to reflect the timing of critical secondary events.

The influence of radiation and chemotherapy-related DNA strand breaks on carcinogenesis: an evaluation

PURPOSE

DNA strand breaks are believed to induce carcinogenesis. This study was conducted to analyze induction and repair of irradiation- and chemotherapy-related strand breaks in vitro.

METHODS

Friend Leukemia cells were exposed to irradiation and various chemotherapeutic agents at different doses and concentrations. Occurrence of strand breaks was determined fluorometrically, measuring the rate of DNA unwinding immediately after exposure and 24 hours later.

RESULTS

The amount of double-stranded DNA decreased significantly for irradiation, doxorubicin, dactinomycin and etoposide (p < or = 0.05, t-test). After 24 hours free of exposure, the persistent damage was detectable for all of these agents but not for irradiated cells, with DNA strand breaks being decreased for etoposide, unchanged for doxorubicin and increased for methotrexate as well as for dactinomycin.

CONCLUSIONS

Severe DNA damage is induced by various chemotherapeutic agents and by irradiation. While repair of chemotherapy-related strand breaks may remain incomplete or prolonged for some chemotherapeutic agents, repair of radiation induced strand breaks is faster and more complete. Therefore chemotherapy-related carcinogenesis may partially be explained by prolonged persistence of DNA strand breaks.

Risk of childhood cancer from fetal irradiation

The association between the low dose of ionizing radiation received by the fetus in utero from diagnostic radiography, particularly in the last trimester of pregnancy, and the subsequent risk of cancer in childhood provides direct evidence against the existence of a threshold dose below which no excess risk arises, and has led to changes in medical practice. Initially reported in 1956, a consistent association has been found in many case-control studies in different countries. The excess relative risk obtained from combining the results of these studies has high statistical significance and suggests that, in the past, a radiographic examination of the abdomen of a pregnant woman produced a proportional increase in risk of about 40%. A corresponding causal relationship is not universally accepted and this interpretation has been challenged on four grounds. On review, the evidence against bias and confounding as alternative explanations for the association is strong. Scrutiny of the objections to causality suggests that they are not, or may not be, valid. A causal explanation is supported by evidence indicating an appropriate dose-response relationship and by animal experiments. It is concluded that radiation doses of the order of 10 mGy received by the fetus in utero produce a consequent increase in the risk of childhood cancer. The excess absolute risk coefficient at this level of exposure is approximately 6% per gray, although the exact value of this risk coefficient remains uncertain.

Thyroid abnormalities among children in the contaminated area related to the Chernobyl accident

Gradual increases of various radiation-related diseases including thyroid cancer following the Chernobyl accident have been recently reported. We have carried out systematic thyroid surveys in school children aged 10-15 years in the highly contaminated area and compared the results with a similar survey in a nonaffected neighboring area as a control. Systematic examinations of the thyroid gland were performed in 888 schoolchildren (408 males and 480 females) in the districts of Chechelsk city with 5 to over 40 Ci/km2 of radiation level for 137Cs. In the control area (Bobruisk city), 521 children with the same age range (229 males and 292 females) were examined. Thyroid surveys were carried out as follows: palpation, ultrasonography, blood examinations of thyroid function, and measurements of daily urinary excretion of iodine. Certain thyroid abnormalities were observed in the high radioactive fallout area more frequently than in the control region. In particular, the prevalence of multiple micronodular lesions in diffuse goiter in the contaminated area was significantly higher than in the control area. However, endemic goiter due to iodine deficiency was present in both districts. The environment factor of iodine deficiency might have resulted in the early occurrence of ultrasonographic thyroid abnormalities attributed to radioactive contamination.

Dosimetry of radiation scattered to thyroid gland from prophylactic cranial irradiation for childhood leukemia

Dosimetry of radiation scattered to the thyroid gland was performed in 17 children (9 boys, 8 girls) who were treated for acute lymphoblastic leukemia and received cranial irradiation for prophylaxis against central nervous system leukemia at a median age of 4 years and 2 months (range, 1 year and 1 month to 14 years). The absorbed dose to the thyroid gland in these children ranged from 0.7% to 7.3% of the dose delivered to the cranium. Thus the total dose to the thyroid gland ranged from 0.13 to 1.32 Gy by the end of the entire course of cranial irradiation. Doses tended to be larger in younger children, but the radiation source also had a large influence on the dose to the thyroid gland; that is, the absorbed dose to the thyroid gland with delivery by linear accelerator was smaller than that by cobalt irradiation. Long-term survivors treated with cranial irradiation for acute leukemia during childhood should be followed for the possible development of thyroid diseases, including malignant tumors, for a long period.

Epidemiology of the childhood acute leukemias

Epidemiologic studies of the childhood leukemias have provided information relevant to several aspects of the care and follow-up of these children. The observations made regarding in utero radiation and ALL risk have certainly curtailed the use of routine obstetric diagnostic radiographs; observations regarding the association between birth weight, fetal loss, and other gestational events provide added enthusiasm for further research into basic biologic events occurring during fetal development; and the genetic patterns of disease supply critical information for genetic counseling and follow-up of affected patients and families. Additionally, the continued epidemiologic surveillance of children with cancer serves to form the foundation from which we will assess any future changes in childhood cancer incidence or pattern. Although not discussed here, the epidemiology of late effects, including second malignancies, reproductive function, and neuropsychologic functioning will assume a more prominent role as more children survive ALL and move into adulthood. While analytic studies have yet to yield an association as strong as the lung cancer/cigarette association in adults, future research designed to isolate biologically homogeneous disease populations for study may lead us to new and important associations. The continued cooperation of large pediatric oncology groups and private physicians is crucial as these future investigations are undertaken.

Treatment of non-toxic multinodular goiter with radioactive iodine

Fourteen patients with large non-toxic multinodular goiters were treated with 20 to 100 mCi (740 to 3,700 MBq) of radioactive iodine (iodine-131). In seven, the goiter had recurred after a partial thyroidectomy and four of these had had two operations. Eight had symptoms of respiratory obstruction, two had dysphagia, and the others sought treatment for cosmetic reasons. After administration of iodine-131, there was a significant decrease in goiter size in 11 of the 14 patients, and all those with obstructive symptoms showed improvement. No significant local side effects occurred, but hypothyroidism and Graves' disease each occurred once during follow-up from one to 13 years. Radioactive iodine in doses of 20 to 100 mCi is an effective, safe therapeutic alternative in patients with large non-toxic multinodular goiter, particularly when there is recurrence following surgery or when there are contraindications to surgery.

Cancer and leukemia risks after low level radiation--controversy, facts and future

Quantification of delayed low dose radiation (LDR) effects is still controversial. The current concept of the shape of the dose-response curve, particularly at the very low levels, is derived primarily by extrapolation from high doses and is affected by economic, social and political implications of cancer yield. Evidence based on epidemiological studies of populations exposed to fallout, occupational, intrauterine or background LDR is limited, due to methodological drawbacks and the need for extremely large sample sizes. Nevertheless, recent data indicate that LDR-induced childhood leukemia and thyroid cancer may exceed the rates predicted on the basis of the linear quadratic curve. The high yield in utero and in early childhood could be associated with low cumulative load of background radiation, and a consequently more effective radiation increment. A long term follow up of children exposed to 90 mSv after scalp X-irradiation revealed a relative risk of 3.8 and an excess risk of about 1.08 per 1000 man-sievert per year for thyroid cancer. Application of these findings to the post-Chernobyl state of events suggests that an increment of up to 20% in thyroid cancer might occur in a population exposed to 5 mSv as an aftermath of a similar accident. Prediction of future risk estimates should therefore be made with alertness and an open mind.

Distinct human leukemia-associated cell surface glycoprotein GP160 defined by monoclonal antibody SN6

In this study, a monoclonal antibody (mAb) termed SN6 was generated by immunizing a mouse with a non-T-cell leukemia antigen preparation isolated from cell membranes of leukemia cells derived from a patient (FJ) with non-T/non-B-cell-type acute lymphoblastic leukemia (ALL). SN6 was tested against a variety of cultured and uncultured human cell specimens by using a sensitive cellular radioimmunoassay. Among the 26 cultured malignant and nonmalignant cell lines tested, SN6 reacted with all of the 6 leukemic non-T/non-B (including pre-B)-cell lines tested--i.e., KM-3, NALM-16, REH, NALL-1, NALM-1, and NALM-6. Of these cell lines, 5 were derived from individual patients with ALL; the remaining 1 was from a patient with chronic myelocytic leukemia in blast crisis. In addition, SN6 reacted with 3 of 3 leukemic myelo-monocytic cell lines tested--i.e., ML-2, HL-60, and U937. SN6 did not react with any other cell lines. A consistent result was obtained with 42 fresh (uncultured) cell specimens derived from individual patients with several different types of leukemias. SN6 reacted with 11 of 16 non-T/non-B (including pre-B)-cell ALL specimens. In addition, it reacted with various myelo-monocytic leukemia cell specimens to various degrees. SN6 did not show a significant reaction with normal peripheral blood cells tested, which included B cells, T cells, granulocytes, monocytes, and erythrocytes. However, it reacted with a small population (approximately 1% as determined by immunofluorescence staining) of normal bone marrow cells. The approximate molecular mass of the glycoprotein antigen defined by SN6 was determined to be 160,000 by radioimmunoprecipitation followed by sodium dodecyl sulfate/polyacrylamide gel electrophoresis. Only one component of 80,000 daltons was formed upon reduction of the 160,000 molecular mass antigen. Therefore, this antigen is apparently a homodimer of a 80,000-dalton subunit. This conclusion was further corroborated by two-dimensional gel analysis, which showed a single well-defined spot for the reduced antigen. We designate this distinct human leukemia-associated cell surface antigen "GP160."

Place of radioactive iodine in treatment of thyrotoxicosis

The effect of treatment of thyrotoxicosis with drugs, radioactive iodine, or surgery in different age groups is reviewed. In Graves' disease and toxic multinodular goitre the remission rate is about 40-50% after antithyroid drugs, but these drugs have little effect in toxic adenoma. Hypothyroidism developed in 35-49% of patients who had had thyroidectomy, and the risks of operation are high. The risk of malignant disease and genetic abnormalities was not significantly greater after treatment with radioactive iodine in any age group. In general, treatment with radioactive iodine should have priority over thyroidectomy at all ages.

Determination of the active marrow dose distribution within the paediatric pelvis and spine

The active marrow dose distributions have been determined inside the pelvis and the spine of two heterogeneous phantoms representing children aged one and five years. Both theoretical calculation and experimental measurement were used to simulate radiographic examinations typical for those ages. Twelve typical radiographic examinations were performed on these phantoms to represent common paediatric diagnostic procedures. The calculated and measured tissue-air ratios were compared for the pelvis and the spine. Uncertainty associated with the measured dose was estimated to be +/- 7%. The results show that most calculated absorbed doses agreed with those measured within twice the coefficient of variation of the calculated value.

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.

Reactions to ionizing radiation

This review deals with essential physical and biologic aspects of ionizing radiation as related to dermatology. The discussion of major physical factors and basic biophysics includes the production of x rays, dose definitions and recent changes in terminology, various factors affecting dose and tissue damage and current radiotherapy methods. The biologic effects and potential risks of ionizing radiation are reviewed in detail, particularly the major nonstochastic and stochastic somatic effects, such as radiation-induced skin cancer, thyroid carcinoma, breast cancer, and other radiogenic neoplasms. Current methods of risk assessment, radiation carcinogenesis, the efficacy of radiation protection technics, and potential genetic effects are critically evaluated.

Childhood leukemias associated with fallout from nuclear testing

Continuing concern over the possible carcinogenic effects of low-level radiation prompted us to study the population of Utah because of its exposure to fallout from 26 nuclear tests between 1951 and 1958. Certain rural counties (high-fallout counties) received most of the fallout during that period. We reviewed all deaths from childhood (under 15 years of age) cancers occurring in the entire state between 1944 and 1975 and assigned them to a cohort of either high or low exposure, depending on whether 15 between 1951 and 1958. For reasons unknown, leukemia mortality among the low-exposure cohort in the high-fallout counties was about half that of the United States and the remainder of the state. Mortality increased by 2.44 times (95 per cent confidence, 1.18 to 5.02) to just slightly above that of the United States in the high-exposure cohort residing in the high-fallout counties, and was greatest in 10- to 14-year-old children. For other childhood cancers, no consistent pattern was found in relation to fallout exposure. The increase in leukemia deaths could be due to fallout or to some other unexplained factor.

Multiple carcinomas following therapy for Hodgkin disease

A 52-year-old man developed synchronous squamous-cell carcinoma of the larynx and middle one-third of the esophagus following treatment of Hodgkin disease. This patient fell into the subgroup of patients treated by intensive radiation therapy followed by intensive chemotherapy. The link between the therapy and subsequent carcinoma is suggestive. Long-term follow-up care of patients with Hodgkin disease demands continuing evaluation of this possible complication.

The effects of therapeutic irradiation on lymphocytes and immunity

The lymphocytotoxic effect of therapeutic irradiation may lead to immune depression. The significance of such effects is yet to be determined in many malignancies, especially in light of the persistant immune depression in many "cured" patients. The present review examines the effects of age, type of cancer, and stage of disease as well as the results of immune parameters following radiation therapy. Factors to be considered in both the analysis of present day data and in future studies are also reviewed.

Long-term effects on external radiation on the pituitary and thyroid glands

Chronic damage following external irradiation of the normal pituitary and thyroid glands, delivered incidentally during radiotherapy of neoplasms of the head and neck may be more common than has been appreciated in the past. A case of a child who developed pituitary dwarfism 5 1/2 years after radiation therapy has been delivered for an embryonal rhabdomyosarcoma of the naso-pharynx is described. A review of similar cases from the literature is presented. Likewise, external irradiation of the normal thyroid gland produces a spectrum of radiation-induced syndromes. Clinical damage to the pituitary and thyroid glands is usually manifested months to years after treatment and is preceded by a long subclinical phase. A careful exclusion of these glands from radiation treatment fields is recommended whenever possible. An early detection of endocrine function abnormalities in patients receiving radiation to these glands is desirable, since appropriate treatment may prevent the deleterious effects of external irradiation of the pituitary and thyroid glands.

Absenteeism among survivors of the atomic bombing of Hiroshima

Atomic bomb survivors who worked at the Atomic Bomb Casualty Commission in Hiroshima during the years 1968-71 and held handbooks identifying them as survivors took significantly more days of both annual leave and sick leave than did matched and paired control subjects. These differences in leave-taking patterns are considered to be due to behavioural causes as they could not be attributed to radiation dose-response effects.