Summary of entire Japanese thorotrast follow-up study: updated 1998

Updated data from two series in a cancer mortality study for a total of 412 Japanese Thorotrast patients were combined. The rate ratio for all deaths of Thorotrast patients, compared to controls, started to increase after a latent period of 20 years after injection of Thorotrast. Rate ratios for liver cancer, liver cirrhosis, leukemia and lung cancer were 35.9, 6.9, 12.5 and 2.0 times higher, respectively, than those for controls.

1998 results of the first series of follow-up studies on Japanese thorotrast patients and their relationships to an autopsy series

The 1998 survey of the first series of epidemiological studies of Japanese Thorotrast patients revealed that 18 (6.9%) were alive and 244 (93.1%) had died among 262 war-wounded veterans to whom Thorotrast had been administered intravascularly. Of 1,630 age- and sex-matched controls, 525 (32.2%) were alive and 1,105 (67.8%) had died. These results indicated a shortening of the life span in patients who had received Thorotrast compared to their controls. Of the patients in the Thorotrast group, the main causes of death were liver malignancies (79, 30.2%), liver cirrhosis (20, 7.6%), blood diseases (9, 3.4%), and cancers of the extrahepatic bile duct (5, 1.9%). Statistical analyses by the chi(2) test and estimation of the relative risk (risk ratio) showed that the incidences of these disorders were significantly higher in the Thorotrast group than in the controls. In the 54-year period from 1945 to 1998, our autopsy series was enlarged to include 398 individuals: 386 injected with Thorotrast intravascularly and 12 injected by other routes. Results of analyses of the 386 autopsy cases given Thorotrast intravascularly were as follows: 263 cases (68.1%) of liver malignancies, 28 cases (7.3%) of liver cirrhosis, 29 cases (7.5%) of blood diseases, 16 cases (4.1%) of lung cancer, 4 cases (1.0%) of malignant peritoneal tumors, 2 cases (0.5%) of bone sarcomas, and 1 case (0.3%) of hemangiosarcoma of the spleen. The relative risks of liver malignancies, blood diseases, bone sarcomas, malignant peritoneal tumors, and hemangiosarcoma of the spleen manifested significantly higher ratios in the Thorotrast autopsy cases (ratio of proportion) than in the autopsy control cases. Histological studies of these autopsied cases revealed that Thorotrast-induced liver malignancies showed remarkable differences in the proportions of histological types of tumors from those of non-Thorotrast liver malignancies since 1975. However, in this survey, we noted a remarkable increase in the incidence of liver malignancy of multiple histological types compared to that in histological controls. Based on the results of our 1998 survey, we estimated attributable risks of Thorotrast-inducedliver malignancies and blood diseases in the life span. Results showed 523 liver malignancies per 10(4) person Gy and 150 blood diseases per 10(4) person Gy for Japanese male Thorotrast carriers (wasted dose 10 years).

Chromosome aberrations in bone marrow cells from Japanese patients with thorotrastosis

Exposure of bone marrow cells to alpha-particle radiation causes various types of chromosome abnormalities and hematological malignancies. We performed chromosome analysis of hematopoietic stem cells from the bone marrow of 52 Japanese patients with thorotrastosis and 21 age-matched controls. The frequency of cells with stable chromosome abnormalities was significantly higher in the patients with thorotrastosis. Further studies found 14 clonal chromosome aberrations in cells from 11 patients (21.2%); clones observed in the cells from 2 of these patients had high frequencies of chromosome abnormalities. In one case, 68 to 100% of the cells analyzed had a large partial loss in the short arm of chromosome 1 and a translocation between the short arms of chromosomes 2 and 3 [46,XY,1p-,t(2p+;3p-)]. The cells from the other patient contained a clone with partial loss of both the short and long arms of chromosome 5 (46,XX,5p-,5q-). The frequency of this clone has been constant for the last 15 years (6-24%). We also analyzed bone marrow mononuclear cells from 17 of the patients for mutations of the TP53 tumor suppressor gene (formerly known as p53). However, no mutation was found in any of the cells, including those from the 2 patients with abnormal clones. Moreover, repeated medical examinations showed no evidence of leukemia or myelodysplasia in these patients. Our study suggests that exposure of bone marrow cells to alpha-particle radiation may induce clonal chromosomal aberrations at a high frequency.

Epidemiological follow-up study of Japanese Thorotrast cases--1980

An epidemiological follow-up study was conducted on 272 Thorotrast-administered war-wounded ex-servicemen to determine their status as of 31 December 1980, after a lapse of 35-43 yr from Thorotrast injection. In the 251 cases who had been intravascularly injected with Thorotrast in the past, 40 malignant hepatic tumors, 3 blood diseases, 2 lung cancers, 1 osteosarcoma, 22 other malignant tumors, and 13 cases of liver cirrhosis were found. The mortality rates due to hepatic and other malignant tumors, blood diseases, and cirrhosis of the liver as well as the overall mortality rate were significantly higher in the intravascular-Thorotrast group than in the controls. In the remaining 21 cases, who had been given Thorotrast by a route other than intravascularly, none of the deaths was found to be related to Thorotrast administration.

Estimated absorbed dose in tissues and radiation effects in Japanese Thorotrast patients

The absorbed dose in the liver, spleen and bone marrow of Thorotrast patients was estimated for 71 autopsy cases. 232Th amounts in tissues were determined from measurements of 228Ac gamma-rays and the activity ratio of 228Ac to 232Th. In calculating the absorbed dose, Kaul's data were used as values of the steady state activity ratio between 232Th and its daughters and the self-absorption of alpha-rays in Thorotrast aggregates. The autopsy cases in which the cumulative dose was estimated consisted of 45 cases of malignant hepatic tumor, 12 cases of liver cirrhosis, 7 cases of blood disease and 7 cases of other diseases. The estimated absorbed doses in the organs were presented and the relationship between the dose and radiation effects on organ tissues was discussed.

Letter: PH1 translocation involving chromosomes 21 and 22

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