[en] The effects of exposure to ionizing radiation on skin cancer incidence in a cohort of atomic bomb (A-bomb) survivors in the Nagasaki Extended Life Span Study (LSS-E85) sample have been investigated. Among 25,942 exposed survivors at risk whose DS86 dose estimates were available, 47 cases of skin cancer including malignant melanoma were confirmed in the Nagasaki Tumor Registry during the period from 1 April 1958 to 31 December 1985. The dose-response relationship of skin cancer based on an additive relative risk model showed linearity without threshold, not a linear-quadratic curve. The excess relative risk (ERR) of 2.2 per gray in the LSS-E85 sample was highly significant (95% confidence limits: 0.5 to 5.0). In addition, the ERR of 3.1 per gray in the Adult Health Study (AHS) sample was also significant (95% confidence limits: 0.6 to 20.3). When dose equivalents based on a relative biological effectiveness of neutrons of 10 were used, the ERR in the former sample decreased to 2.0 per sievert (95% confidence limits: 0.7-4.5), and the risk in the latter group also declined, to 2.7 per sievert (95% confidence limits: 0.6-17.8). The ERRs did not differ significantly between males and females in the LSS-E85 and AHS samples, but a highly significant increase was observed for the ERR of age at exposure and time trend since exposure. The ERR of skin cancer cases including and excluding 4 malignant melanoma cases for the LSS-E85 sample (there were no malignant melanoma cases in the AHS sample) showed almost the same linear dose response. This is the first report to demonstrate a highly significant dose-response relationship between A-bomb exposure and skin cancer incidence. (author)

[en] Skin specimens were obtained from 11 A-bomb survivors, 10 of whom had been exposed at ≤2300 m from the hypocenter, and 7 non-exposed controls. There was a higher frequency (12%, 147/1222 cells) of chromosome aberrations in the exposed group compared with 1.2% (4/341 cells) in the control group. This suggests that aberrant cells are still present in the skin tissue 40 years or more after the bombing. Of 147 cells, 136 cells (91.3%) showed translocation of chromosome. Other aberrations, such as inversion, deletion, dicentric chromosome and acentric fragment, were observed in only 3.8%. These aberrant cells tended to be observed in A-bomb survivors exposed to high doses and with a history of severe acute symptoms. One hundred and twenty two (83%) of 136 aberrant cells were obtained from 3 A-bomb survivors, which has important implications for marked proliferation of specific clone cells. In an analysis by B-band staining technique for the 122 cells, band sites of break point were found to correspond to loci of protooncogenes, suggesting the involvement in aggressive proliferation of clone cells. (Namekawa, K)

[en] Data from 140 A-bomb survivors with skin cancer were analyzed with the purpose of elucidating the relationship between atomic bombing and skin cancer. The incidence of skin cancer was significantly correlated with the distance from the hypocenter (p<0.01), regardless of sex. Basal cell epithelioma was the most predominant, followed by squamous cell carcinoma. Histology of skin cancer seemed independent of the distance. Since 1965, the incidence of skin cancer has been increased with aging in A-bomb survivors exposed at ≤2500 m from the hypocenter. It has been significantly higher since 1975 in the ≤2500 m group than in the ≥3000 m group. (N.K.)

[en] This study was designed to investigate the correlation between the incidence of skin cancer and exposure distance in Nagasaki A-bomb survivors. When 140 A-bomb survivors, collected from 31 medical facilities in Nagasaki and its surrounding areas, were analyzed using logistic regression model based on the data of 66,276 A-bomb survivors, the incidence of skin cancer was found to be significantly lower in A-bomb survivors exposed farther from the hypocenter. This was also noted when confining to either men or women. Among 25,942 A-bomb survivors, available using DS85 dosimetry system, in the RERF-Life Span Study sample and RERF-Adult Health Study sample (1958-1985), 47 A-bomb survivors were found to have skin cancer. For them, higher incidence of skin cancer was associated with larger radiation doses. Dose-response relationship for skin cancer was linear. Twenty five of the 47 A-bomb survivors (53%) histologically had basal cell carcinoma. Since 1975, an increased rate in the incidence of skin cancer has been noticeable in A-bomb survivors exposed at ≤2,500 m than those exposed at ≥3,000 m. The number of excess cases of skin cancer was found to have been steadily increased since 1958. (N.K.)

[en] Of the 66,276 Nagasaki atomic bomb survivors registered at the Scientific Data Center for the Atomic Bomb Disaster at the Nagasaki University School of Medicine, 140 were identified as having skin cancer from the records of 31 hospitals in Nagasaki City. From the cases of these survivors, a statistical analysis was made of the incidence of skin cancers by age, gender, histology and latency period in Nagasaki atomic bomb survivors. The results showed a high correlation between the incidence of skin cancer and distance from the blast hypocenter, and that the incidence of skin cancer in the Nagasaki survivors appears now to be increasing with exposure distance. (author)

[en] Chromosomal abberation of bone marrow cells in healthy persons and patients with various hematologic diseases both of the exposed and the non-exposed were discussed. One healthy a-bomb survivor exposed near the hypocenter and structural abnormality of chromosomes closely similar to that found out in a small number of patients with hematologic diseases, but clone formation was not recognized. Though it was clarified that there was chromosomal abberation peculiar to each hematologic disease, specific chromosomal abberation peculiar to a-bomb survivors with hematologic diseases was not recognized. There were many a-bomb survivors with hemopoietic dysplasia who had structural abnormality of chromosomes, and their frequency was significantly higher than that of the non-exposed. (Tsunoda, M.)

[en] The incidence of skin cancer during the period 1958-1985 was examined in the population registered in the life span study extension (LSSE) and the adult health study (AHS). Among 25,942 A-bomb survivors in whom DS86 was available, skin cancer was confirmed in 47 A-bomb survivors. These A-bomb survivors consisted of 24 males and 23 females. According to DS86 dosimetry system, ten A-bomb survivors had been exposed to 0.50 Gy or more. The most common histology was basal cell epithelioma (n=25), followed by malignant melanoma (n=4) and basosquamous cell carcinoma and sweat gland carcinoma (one each). In the group of 0.50 Gy or more, the incidence of occurrence of skin cancer was 20.8/100,000 population per year (PY) for the LSSE population and 22.8/100,000 PY for the AHS population. In the group of 0.01-0.49 Gy, it was 6.8/100,000 PY for the LSSE population and 12.8/100,000 PY for the AHS population. It was significantly associated with higher exposure doses. The dose-response relationship was linear. (N.K.)

[en] Whether cytoplasmic inclusion (CI) is useful as an index for the effects of atomic bomb radiation was discussed. Subjects of this study were 16 healthy people with chromosomal aberration due to atomic bomb radiation (8 males and 8 females) (Group 1) and 31 people with a history of malignant tumors (10 males and 21 females) (Group 2) who were living in Nagasaki City. For the purpose of observing chromosome and CI, blood was collected together in the period from 1970 to 1972. In Group 1, a total number of cells obseved was 14,513 and no Cl was found in them. In Group 2, a total number of cells observed was 31,289, and CI was found in 2 of them. CI which is a reaction of a living body in an acute stage following accidental irradiation seemed to have already disappeared. Therefore, usefulness of CI as an indicator for the effect of atomic bomb radiation was denied. (Ueda, J.)

[en] Cytogenetic and moleculobiological analyses were made for the relationships between leukemogenesis and both A-bombing and myelodysplastic syndrome (MDS) in two A-bomb survivors developing MDS. Both of the survivors had entered the city early after A-bombing (two days and seven days later). They had a normal karyotype of bone marrow cells, but had point mutation of the N-ras proto-oncogene. In one survivor, MDS (RAEB-t) was transferred to leukemia; and in the other survivor, leukemia was not observed during a follow-up of more than one year. There was no definitive correlation between A-bombing exposure and the development of MDS in either survivor. Point mutation of the N-ras proto-oncogene may be a possible factor, but not a critical factor, for developing leukemia. (N.K.)

[en] Among a total of 65,268 Nagasaki atomic bomb survivors recorded in the Scientific Data Center of Atomic Bomb Disaster, Nagasaki University School of Medicine, 140 cases with skin cancer were collected from 31 hospitals in Nagasaki City from 1961 through 1987. Subsequently, these cases of skin cancer in Nagasaki atomic bomb survivors were statistically analyzed in relation to the estimated distance from the hypocenter by age, sex, histology and latent period. The results were as follows: (1) A high correlation was observed between the incidence of skin cancer and the distance from the hypocenter. (2) The incidence of skin cancer in Nagasaki atomic bomb survivors now appears to be increasing in relation to exposure distance. (3) Among 140 cases, basal cell epithelioma was observed in 67 cases (47.9%) and squamous cell carcinoma in 43 cases (30.7%). (author)