Solid cancer incidence in atomic bomb survivors: 1958-1998.

This is the second general report on radiation effects on the incidence of solid cancers (cancers other than malignancies of the blood or blood-forming organs) among members of the Life Span Study (LSS) cohort of Hiroshima and Nagasaki atomic bomb survivors. The analyses were based on 17,448 first primary cancers (including non-melanoma skin cancer) diagnosed from 1958 through 1998 among 105,427 cohort members with individual dose estimates who were alive and not known to have had cancer prior to 1958. Radiation-associated relative risks and excess rates were considered for all solid cancers as a group, for 19 specific cancer sites or groups of sites, and for five histology groups. Poisson regression methods were used to investigate the magnitude of the radiation-associated risks, the shape of the dose response, how these risks vary with gender, age at exposure, and attained age, and the evidence for inter-site variation in the levels and patterns of the excess risk. For all solid cancers as a group, it was estimated that about 850 (about 11%) of the cases among cohort members with colon doses in excess of 0.005 Gy were associated with atomic bomb radiation exposure. The data were consistent with a linear dose response over the 0- to 2-Gy range, while there was some flattening of the dose response at higher doses. Furthermore, there is a statistically significant dose response when analyses were limited to cohort members with doses of 0.15 Gy or less. The excess risks for all solid cancers as a group and many individual sites exhibit significant variation with gender, attained age, and age at exposure. It was estimated that, at age 70 after exposure at age 30, solid cancer rates increase by about 35% per Gy (90% CI 28%; 43%) for men and 58% per Gy (43%; 69%) for women. For all solid cancers as a group, the excess relative risk (ERR per Gy) decreases by about 17% per decade increase in age at exposure (90% CI 7%; 25%) after allowing for attained-age effects, while the ERR decreased in proportion to attained age to the power 1.65 (90% CI 2.1; 1.2) after allowing for age at exposure. Despite the decline in the ERR with attained age, excess absolute rates appeared to increase throughout the study period, providing further evidence that radiation-associated increases in cancer rates persist throughout life regardless of age at exposure. For all solid cancers as a group, women had somewhat higher excess absolute rates than men (F:M ratio 1.4; 90% CI 1.1; 1.8), but this difference disappears when the analysis was restricted to non-gender-specific cancers. Significant radiation-associated increases in risk were seen for most sites, including oral cavity, esophagus, stomach, colon, liver, lung, non-melanoma skin, breast, ovary, bladder, nervous system and thyroid. Although there was no indication of a statistically significant dose response for cancers of the pancreas, prostate and kidney, the excess relative risks for these sites were also consistent with that for all solid cancers as a group. Dose-response estimates for cancers of the rectum, gallbladder and uterus were not statistically significant, and there were suggestions that the risks for these sites may be lower than those for all solid cancers combined. However, there was emerging evidence from the present data that exposure as a child may increase risks of cancer of the body of the uterus. Elevated risks were seen for all of the five broadly classified histological groups considered, including squamous cell carcinoma, adenocarcinoma, other epithelial cancers, sarcomas and other non-epithelial cancers. Although the data were limited, there was a significant radiation-associated increase in the risk of cancer occurring in adolescence and young adulthood. In view of the persisting increase in solid cancer risks, the LSS should continue to provide important new information on radiation exposure and solid cancer risks for at least another 15 to 20 years.

Malignant and benign ovarian neoplasms among atomic bomb survivors, Hiroshima and Nagasaki, 1950-80.

For 1950-80, 194 ovarian cancer cases were ascertained among the 70,030 females of the Radiation Effects Research Foundation's Life-Span Study E-85 sample, and 106 autopsied cases with benign ovarian neoplasms were ascertained among all 3,046 autopsies performed in the same sample. On the basis of microscopic review, 66% of the cancer and 84% of the benign tumor cases were classified by histologic type. The age-adjusted ovarian cancer incidence rates showed a statistically significant increase with increased exposure dose, both in the entire exposed group (P less than .01) and in the microscopically reviewed subset (P less than .01). This dose response was only significant (P less than .01) in the latter half of the study period, 1965-80. The radiation effect was higher in the younger age group at the time of the bomb (ATB) for the specific attained age or was adjusted for attained age. In general, relative risk (greater than or equal to 100 rad vs. 0 rad) did not differ by attained age, except for the youngest age group, less than 20 years old ATB, where the relative risk tended to decrease with increased attained age, although cases were few in number and follow-up study was necessary. Estimated minimum latent period for radiation-induced ovarian cancer seemed to be 15-20 years. The proportion of autopsied cases with benign ovarian tumor increased with increasing exposure dose, both in the entire series of cases (P less than .05) and in the microscopically reviewed subset. Statistical significance, however, was not achieved in the latter group (P greater than .10). The distribution of histologic types of both cancer and benign tumor of the ovary did not vary significantly with radiation dose. The data are consistent with the hypothesis that radiation injury of the ovaries and secondary excess of gonadotropic hormones are important causative factors in the development of ovarian neoplasms.

Malignant breast tumors among atomic bomb survivors, Hiroshima and Nagasaki, 1950-74.

For 1950-74, 360 cases of malignant breast tumors were identified among the 63,000 females of the Radiation Effects Research Foundation's (Hiroshima and Nagasaki) Extended Life-Span Study sample of survivors of the 1945 atomic bombings of Hiroshima and Nagasaki; 288 of these females were residing in one of these two cities at the time of bombing (ATB). Two-thirds of all cases were classified as breast cancers on the basis of microscopic review of slides, and 108 cases received an estimated breast tissue dose of at least 10 rads. The number of cases of radiogenic breast cancer could be well estimated by a linear function of radiation dose for tissue doses below 200 rads. Excess risk estimates, based on this function, for women 10-19, 20-29, 30-39, and 50 years old or older ATB were 7.3, 4.2, 2.6, and 4.7 cases per million women per year per rad, respectively. Women irradiated in their forties showed no dose effect. Among all women who received at least 10 rads, those irradiated before age 20 years will have experienced the highest rates of breast cancer throughout their lifetimes. Separate excess risk estimates for Hiroshima and Nagasaki did not differ significantly, which indicates that for radiogenic breast cancer the effects of neutrons (emitted only in the Hiroshima explosion) and gamma radiation were about equal. Radiation did not reduce the latency period for the development of breast cancer, which was at least 10 years. The distribution of histologic types of cancers did not vary significantly with radiation dose. The data suggested that irradiation prior to menarche conferred a greater risk than irradiation after menarche.

Novel mutations in the myocilin gene in Japanese glaucoma patients.

Myocilin is a gene responsible for juvenile onset primary open angle glaucoma (POAG) mapped as the GLC1A locus and, many mutations have been reported worldwide. Some mutations were found not only in patients with juvenile onset POAG, but also in patients with late onset POAG and in patients with normal tension glaucoma. To investigate the mutation prevalence in Japan, we performed a mutation analysis in 140 unrelated Japanese patients. We have identified the 10 sequence variants, of which four were highly probable for disease-causing mutations (Arg46ter, Arg158Gln, Ile360Asn, and Ala363Thr), and six polymorphisms (Gln19His, Arg76Lys, Asp208Glu, Val439Val, Arg470His, and Ala488Ala). Thus, myocilin mutations were found at the rate of 4/140 (2.9%) probands, similar to previous reports with other ethnic populations.

Disruption of antigen-induced airway inflammation and airway hyper-responsiveness in low affinity neurotrophin receptor p75 gene deficient mice.

1. Recently, much attention has been paid to the relationship between the nervous and immune systems. The present study was conducted to clarify the role of neurotrophin low affinity receptor (p75N) in allergic airway inflammation and hyper-responsiveness (AHR) in mice by employing p75N gene deficient mice. 2. Mice were immunized twice by intraperitoneal injections of ovalbumin (OA) at intervals of 12 days. OA was inhaled 10 days after the secondary immunization and repeated three times at 4 days interval. Twenty-four hours after the last inhalation, airway responsiveness to acetylcholine was measured and bronchoalveolar lavage fluid (BALF) was obtained for examining the number of inflammatory cells and the level of cytokines. Serum immunoglobulin was measured as a marker of systemic immune response before the final inhalation. 3. In wild-type mice, repeated antigen provocation resulted in airway eosinophilia, AHR and elevations in serum IgE and interleukin (IL)-4 and -5 in BALF. In p75N gene deficient mice, none of the above parameters was observed after antigen provocation. The antigen-induced production of interferon (IFN)-gamma and nerve growth factor (NGF) were not altered by depletion of p75N gene. 4. The present findings suggest that p75 gene deficiency disrupt an allergic airway inflammation and AHR in mice by interfering type 2 helper T (Th2) cell responses.

Reproducibility of major diagnoses in a binational study of lung cancer in uranium miners and atomic bomb survivors.

A binational panel of four Japanese and four American pathologists examined 208 pulmonary neoplasms, according to the World Health Organization (WHO) recommendations, second edition, for the histologic typing of lung tumors. The study design included independent evaluations by pathologists working alone, followed by group reviews. The individual evaluations, and their implications for reproducibility of the WHO recommendations, are reported. Consensus (agreement by six or more pathologists) with respect to major (ie, first digit) diagnosis was obtained for 76.4% of the cases. Consensus was obtained for 72.5% of the cases with any major diagnosis of small cell cancer; the comparable figures for adenocarcinoma and squamous cell carcinoma were 56% and 48%, respectively. American pathologists were twice as likely as Japanese pathologists to diagnose large-cell cancer, the only significant national difference. Consensus was far less frequent with the minor (ie, second digit) diagnosis categories. This study shows that lung cancers continue to be difficult to classify reproducibly.

Incidence of female breast cancer among atomic bomb survivors, 1950-1985.

An incidence survey among atomic bomb survivors identified 807 breast cancer cases, and 20 second breast cancers. As in earlier surveys of the Life Span Study population, a strongly linear radiation dose response was found, with the highest dose-specific excess relative risk (ERR) among survivors under 20 years old at the time of the bombings. Sixty-eight of the cases were under 10 years old at exposure, strengthening earlier reports of a marked excess risk associated with exposure during infancy and childhood. A much lower, but marginally significant, dose response was seen among women exposed at 40 years and older. It was not possible, however, to discriminate statistically between age at exposure and age at observation for risk as the more important determinant of ERR per unit dose. A 13-fold ERR at 1 Sv was found for breast cancer occurring before age 35, compared to a 2-fold excess after age 35, among survivors exposed before age 20. This a posteriori finding, based on 27 exposed, known-dose, early-onset cases, suggests the possible existence of a susceptible genetic subgroup. Further studies, involving family histories of cancer and investigations at the molecular level, are suggested to determine whether such a subgroup exists.

Incidence of female breast cancer among atomic bomb survivors, Hiroshima and Nagasaki, 1950-1980.

Ascertainment of breast cancer incidence among the cohort of the RERF Life Span Study extended sample identified 574 breast cancers among 564 cases diagnosed during 1950-1980 of which 412 cancers were reviewed microscopically. There were no dose-dependent differences with respect to diagnostic certainty or histological type. As in previous studies, the dose response appeared to be roughly linear and did not differ between the two cities. The most remarkable new finding was the emergence of a radiation-related excess among women under 10 years of age at exposure. The risk of radiogenic breast cancer appears to decrease with increasing age at exposure, whether expressed in relative or absolute terms. These results suggest that exposure of female breast tissue to ionizing radiation at any time during the first four decades of life, even during the premature stage, can cause breast cancer later in life, and that the length of time that tumor promoters such as endogenous hormones operate following exposure has an important influence on the development of radiation-induced breast cancer. An unresolved question is whether breast cancer risk is increased by radiation exposure at ages older than 40.

Effects of radiation on incidence of primary liver cancer among atomic bomb survivors.

We describe the radiation risk for primary liver cancers between 1958 and 1987 in a cohort of atomic bomb survivors in Hiroshima and Nagasaki, Japan. The analysis is based on a comprehensive pathology review of known or suspected liver neoplasms that generated 518 incident, first primary cases, mostly hepatocellular carcinoma. Excess relative risk from atomic bomb radiation was linear: 0.81 per sievert weighted liver dose (95% CI [0.32, 1.43]; P < 0.001). Males and females had similar relative risk so that, given a threefold higher background incidence in males, the radiation-related excess incidence was substantially higher in males. Excess risk peaked for those with age at exposure in the early 20s; there was essentially no excess risk in those exposed before age 10 or after age 45. Whether this was due to a difference in sensitivity or possible confounding by other factors could not be addressed retrospectively in the full cohort. A paucity of cholangiocarcinoma and hemangiosarcoma cases suggested that they are not significantly associated with whole-body radiation exposure, as they are with the internal alpha-particle-emitting radiological contrast medium Thorotrast. Because most of the radiation-related excess cases occurred among males, it is important to ascertain what factors put men at greater risk of radiation-related liver cancer.

Radiation-associated lung cancer: a comparison of the histology of lung cancers in uranium miners and survivors of the atomic bombings of Hiroshima and Nagasaki.

A binational panel of Japanese and American pulmonary pathologists reviewed tissue slides of lung cancer cases diagnosed among Japanese A-bomb survivors and American uranium miners and classified the cases according to histological subtype. Blind reviews were completed on slides from 92 uranium miners and 108 A-bomb survivors, without knowledge of population, sex, age, smoking history, or level of radiation exposure. Consensus diagnoses were obtained with respect to principal subtype, including squamous-cell cancer, small-cell cancer, adenocarcinoma, and less frequent subtypes. The results were analyzed in terms of population, radiation dose, and smoking history. As expected, the proportion of squamous-cell cancer was positively related to smoking history in both populations. The relative frequencies of small-cell cancer and adenocarcinoma were very different in the two populations, but this difference was accounted for adequately by differences in radiation dose or, more specifically, dose-based relative risk estimates based on published data. Radiation-induced cancers appeared more likely to be of the small-cell subtype, and less likely to be adenocarcinomas, in both populations. The data appeared to require no additional explanation in terms of radiation quality (alpha particles vs gamma rays), uniform or local irradiation, inhaled vs external radiation source, or other population difference.

Incidence of salivary gland tumors among atomic bomb survivors, 1950-1987. Evaluation of radiation-related risk.

A wide-ranging search for benign and malignant tumors of the major and minor salivary glands among members of the Life Span Study sample of the Radiation Effects Research Foundation identified 41 malignant and 94 benign incident tumors, including 14 malignant and 12 benign tumors of the minor salivary gland, plus 10 major gland tumors of unknown behavior. Dose-response analyses found statistically significant increases in risk with increasing A-bomb dose for both cancer and benign tumors. Estimated relative risks at 1 Sv weighted tissue kerma (RR1Sv, with 90% confidence interval in parentheses) were 4.5 (2.5-8.5) for cancer and 1.7 (1.1-2.7) for benign tumors. When analyzed by histological subtype within these two broad groups, it appeared that most of the dose response for malignant tumors was provided by an exceptionally strong dose response for mucoepidermoid carcinoma [11 exposed cases with dose estimates, RR1Sv = 9.3 (3.5-30.6)], and most or all of that for benign tumors corresponded to Warthin's tumor [12 cases, RR1Sv = 4.1 (1.6-11.3)]. There was a marginal dose response for malignant tumors other than mucoepidermoid carcinoma [RR1Sv = 2.4 (0.99-5.7)] but no significant trend for benign tumors other than Warthin's tumor [RR1Sv = 1.3 (0.9-2.2)]. Re-examination of the original data from published studies of other irradiated populations may shed new light on the remarkable type specificity of the salivary tumor dose response observed in the present study.

RNA from decades-old archival tissue blocks for retrospective studies.

The validity of molecular studies using DNA and RNA extracted from decades-old formalin-fixed and paraffin-embedded tissue blocks has been demonstrated. The quality and usability of DNA and RNA from archival tissues are modified by various factors, such as the fixative, the fixation time, and the postmortem time. However, in contrast to DNA, there are no comprehensive studies quantitatively addressing the feasibility of RNA from old (more than 10 years) archival samples. This study examined the integrity of RNA extracted from 738 autopsy liver and 63 autopsy thyroid cancer tissue blocks procured during a span of nearly four decades, beginning in 1952 and ending in 1989, from the atomic bomb survivors. The integrity of RNA was assessed by amplification of c-BCR messenger RNA (mRNA) between two sequential exons with an intervening intron by reverse-transcription polymerase chain reaction (RT-PCR). The integrity of RNA was influenced by the age of the samples and the postmortem time, but not by the formalin-fixation period. It was possible to amplify more than 60% of the samples. Using these RNAs, the HCV genome in liver cancers and the H4-RET gene in thyroid cancers were detectable. This study illustrates the possibility of molecular studies using RNA from routinely prepared paraffin blocks stored for long periods and provides the statistics and critical factors to consider in assessing the feasibility of such contemplated studies.

Liver cancer in atomic-bomb survivors: histological characteristics and relationships to radiation and hepatitis B and C viruses.

Histological features of primary liver cancer among atomic-bomb survivors and their relationship to hepatitis B (HBV) and C viral (HCV) infections are of special interest because of the increased risk of liver cancer in persons exposed to ionizing radiation and the high and increasing liver cancer rates in Japan and elsewhere. We conducted a pathology review of liver cancers occurring from 1958 to 1987 among subjects in the 120,321 member cohort of 1945 Hiroshima and Nagasaki residents. A panel of pathologists classified tumor histological types and defined accompanying cirrhotic changes of the liver. Archival tissue samples were assessed for HBV using pathology stains and PCR. Reverse transcriptase (RT) PCR was used to determine HCV status. We used unconditional logistic regression to compare 302 hepatocellular carcinoma (HCC) cases to 53 cholangiocarcinoma (CC) cases, adjusting for age, year of diagnosis, sex and viral status. Cirrhotic changes occurred significantly more often among HCC than CC cases (76% in HCC and 6% in CC). Compared to CC cases, HCC cases were 10.9 times more likely to be HBV-positive (95% confidence interval: 2.1-83.2) and 4.3 times more likely to be HCV-positive (95% confidence interval: 1.1-20.5). No significant differences were found between HCC and CC cases in radiation exposures. The predominance of HCC in the atomic-bomb survivors follows the background liver cancer pattern in Japan. Our findings suggest that HBV and HCV are involved in the pathogenesis of HCC with or without cirrhosis and are significantly less important in that of CC.

Tumorigenicity study of butyl and isobutyl p-hydroxybenzoates administered orally to mice.

Butyl p-hydroxybenzoate (n-BHB) and isobutyl p-hydroxybenzoate (i-BHB) were administered orally to ICR/Jcl mice at concentrations of 0.6 (maximum tolerated dose), 0.3 or 0.15% in the diet for up to 102 wk. Tumours were observed at various sites including the haematopoietic system, the lung and the soft tissue. However, at none of the sites did the tumour incidence or the time to death with tumours differ significantly from that in the untreated control group.

Tumorigenicity study of disodium glycyrrhizinate administered orally to mice.

Disodium glycyrrhizinate (DG) was administered at concentrations of 0.15 (maximum tolerated dose), 0.08, 0.04 or 0% in the drinking-water to groups of 50, 70, 60 and 60 male B6C3F1 mice, respectively. Female groups, each consisting of 50 mice, were given DG in the drinking-water at concentrations of 0.3 (maximum tolerated dose), 0.15, 0.08 or 0%. Treatment was continued for 96 wk and the experiment was terminated at wk 110. There was no difference between treated and control groups in tumour incidence, in the latent period before tumours appeared or in the distribution of different types of tumour. Thus the long-term oral administration of DG to mice did not yield any evidence of chronic toxicity or tumorigenicity.

A novel biological aspect of ovarian oxytocin: gene expression of oxytocin and oxytocin receptor in cumulus/luteal cells and the effect of oxytocin on embryogenesis in fertilized oocytes.

Recently, several authors have reported the existence of oxytocin (OT) in mammalian granulosa-luteal cells after ovulation. The purpose of this study was to examine the evidence for gene expression and localization of OT and OT receptor (OTR) in the cumulus cells surrounding the oocytes. Cumulus cells with mature oocytes were obtained from experimental and clinical in vitro fertilization-embryo transfer (IVF-ET) programs. OT and OTR gene expression was analyzed with reverse transcriptase-polymerase chain reaction (RT-PCR) and RT-PCR/single strand conformation polymorphism (SSCP). OT gene expression was detected in mouse and human cumulus cells. The results of RT-PCR/SSCP showed that the structure of OT mRNA in cumulus cells was similar to that in the hypothalamus. Furthermore, OTR gene expression was clearly demonstrated in human cumulus cells, and a weak positive signal was observed in human oocytes. Immunocytochemical staining of OTR was clearly detected in human cumulus cells. The rate of mouse blastocyst development was significantly higher in the group cultured with OT than that without OT. These results are the first observations of simultaneous OT and OTR gene expression in cumulus cells, suggesting that ovarian OT might have some physiological role in the early stage of embryo development.

Tumorigenicity study of sodium erythorbate administered orally to mice.

Sodium erythorbate (SE) was administered at concentrations of 0, 1.25, or 2.5% (maximum tolerated dose, MTD) in the drinking-water to groups of 50 male B6C3F1 mice respectively. Female groups, each consisting of 50 mice, received SE in the drinking-water at concentrations of 0, 2.5 or 5% (MTD). Treatment continued for 96 wks and the experiment was terminated during wk 110. Tumors were observed at various sites including the liver, hematopoietic system, lung and soft tissue. However, at any of the sites, the tumor incidence, the time to death with tumors or the histological distribution of tumors did not differ significantly from those in the untreated control group. Thus, the present study did not demonstrate a tumorigenic effect of SE on B6C3F1 mice by means of oral administration.

[Effects of combined instillation of dapiprazole and epinephrine on human anterior chamber depth, intraocular pressure and pupil diameter].

Pilocarpine, a first choice drug for primary angle closure glaucoma (PACG), is reported to produce shallow anterior chamber and posterior synechia and consequently a small immobile pupil. In this paper, dapiprazole, a newly synthesized alpha 1 blocker, was given topically in combination with epinephrine eye drops to 15 healthy volunteers and 10 patients with PACG. In both volunteers and patients, the treated eyes revealed deeper anterior chambers, thinner lenses and significant IOP reduction after the combined instillation of dapiprazole and epinephrine. Though light reaction was preserved, mild miosis was observed in volunteers, but no pupillary change in patients. The conjunctival hyperemia induced by dapiprazole was reversed by additional instillation of epinephrine. Burning sensation was the only side effect observed after instillation of dapiprazole. In conclusion, the combined instillation of dapiprazole and epinephrine appears to be a good choice for the therapy of PACG.

[Early cancer and related changes in the bronchial epithelium of former mustard gas workers].

The bronchial epithelium taken in stepwise transverse sections was examined histologically in 66 autopsy cases, composed of groups consisting of 19 mustard gas (MG) ex-workers with lung cancer, 17 MG ex-workers with non-lung cancer, 10 non-MG lung cancer cases, and 20 non-MG non-lung cancer cases. An additional 5 surgical lung cancer specimens removed from MG ex-workers were also examined. From these groups, foci of moderate or severe atypia including cellular atypia, dysplasia and carcinoma in situ (CIS), detected in the total number of slides for each autopsy group, were counted as 146 out of 3,485, 72 out of 2,226, 70 out of 3,797, and 18 out of 4,611, respectively. Seven CIS lesions were detected from among all MG-exposed cases and 1 CIS lesion was found in a non-MG lung cancer case. Six of these occurred with dysplasia and 4 were associated with early invasion. Among 62 autopsy cases with known smoking histories, multivariate analysis revealed a significant correlation between the incidence rate of atypia and MG exposure only in non-lung cancer cases: the incidence rate of atypia was also influenced significantly by smoking and age. Among lung cancer cases, the incidence rate of atypia was significantly higher (p less than 0.01) in cases of squamous cell carcinoma than those of small cell carcinoma.