Breast and other cancers in 1445 blood relatives of 75 Nordic patients with ataxia telangiectasia

Epidemiological studies have consistently shown elevated rates of breast cancer among female blood relatives of patients with ataxia telangiectasia (AT), a rare autosomal recessive disease. A large proportion of the members of AT families are carriers of AT-causing gene mutations in ATM (Ataxia Telangiectasia Mutated), and it has been hypothesised that these otherwise healthy carriers are predisposed to breast cancer. This is an extended and enlarged follow-up study of cancer incidence in blood relatives of 75 patients with verified AT in 66 Nordic families. Blood relatives were identified through population registry linkages, and the occurrence of cancer was determined from cancer registry files in each country and compared with national incidence rates. The ATM mutation carrier probabilities of relatives were assigned from the combined information on location in family, consanguinity, if any, and supplementary carrier screening in some families. Among the 1445 blood relatives of AT patients, 225 cancers were observed, with 170.4 expected, yielding a standardised incidence ratio (SIR) of 1.3 (95% confidence interval (CI), 1.1-1.4). Invasive breast cancer occurred in 34 female relatives (SIR, 1.7; 95% CI, 1.2-2.4) and was diagnosed in 21 women before the age of 55 years (SIR, 2.9; 95% CI, 1.8-4.5), including seven mothers of probands (SIR, 8.1; 95% CI, 3.3-17). When the group of mothers was excluded, no clear relationship was observed between the allocated mutation carrier probability of each family member and the extent of breast cancer risk. We concluded that the increased risk for female breast cancer seen in 66 Nordic AT families appeared to be restricted to women under the age of 55 years and was due mainly to a very high risk in the group of mothers. The findings of breast cancer risk in mothers, but not other likely mutation carriers, in this and other studies raises questions about the hypothesis of a simple causal relationship with ATM heterozygosity.

Cancer in patients with ataxia-telangiectasia and in their relatives in the nordic countries

BACKGROUND

Epidemiologic studies of the families of patients with ataxia-telangiectasia (A-T), a recessive genetic neurologic disorder caused by mutation of the ATM gene, suggest that heterozygous carriers of an ATM mutation are at increased risk of cancer. A population-based study of cancer incidence in A-T families with unbiased selection and tracing of relatives would confirm this hypothesis.

METHODS

We conducted a study in the Nordic countries of 1218 blood relatives of 56 A-T patients from 50 families. The relatives were identified from population registries, and the occurrence of cancer was determined from cancer registry files in each country and compared with national incidence rates. All statistical tests were two-sided.

RESULTS

Among the 56 patients with A-T, we observed six cases of cancer (four leukemias and two non-Hodgkin's lymphomas) compared with 0.16 expected, yielding a standardized incidence ratio (SIR) of 37 (95% confidence interval [CI] = 13 to 80). Among the 1218 relatives, 150 cancers were recorded, with 126 expected (SIR = 1.19; 95% CI = 1.01 to 1.40). Invasive breast cancer occurred in 21 female relatives of A-T patients (SIR = 1.54; 95% CI = 0.95 to 2.36), including five of the 50 mothers (all of whom are obligate ATM mutation carriers) (SIR = 7.1; 95% CI = 2.3 to 17). Relatives who were less likely to be carriers of a mutant ATM allele had no increase or only a modest, statistically nonsignificant increase in the risk of breast cancer. There was no evidence of increased risk for cancer at any other site.

CONCLUSIONS

We confirmed the previously recognized high risk of lymphoma and leukemia in A-T patients. Our data are also consistent with an increased risk of breast cancer among blood relatives of A-T patients. The epidemiologic findings suggest, however, that, even if ATM mutations are responsible for some breast cancer cases, ATM is a relatively weak genetic risk factor for the disease.

Lung cancer and indoor air pollution in rural china

PURPOSE: Indoor air pollution has been linked with lung cancer in China. In contrast to previous studies conducted in urban areas with high levels of industrial pollution, we undertook a lung cancer case-control study in a rural area of China, where residents live in underground dwellings. We evaluated the effects of radon, wood and coal combustion, cooking oil fumes, and environmental tobacco smoke on lung cancer risk.METHODS: We enrolled 886 lung cancer cases (656 males, 230 females) diagnosed between 1994-98, aged 30-75 years and 1765 frequency matched population-based controls from two prefectures in Gansu Province in Northwestern China. We conducted interviews with subjects or next of kin on smoking, housing characteristics, fuel use and cooking practices. Year-long radon detectors were placed in current and former homes of subjects.RESULTS: Subjects primarily used coal (22%), wood (56%) or a combination of both (22%) for heating. Odds Ratios (OR) for lung cancer rose with increasing percent of time that coal was used to heat homes over the past 30 years (ORs = 1.00, 1.17, 1.35, 1.23 compared to wood only, adjusted to smoking, P for trend = 0.025). Among non-smoking females and males, the OR for ever exposed to environmental tobacco smoke was 1.19, 95% CI = 0.7-2.0 with a significant trend for increasing years of exposure. Fumes from cooking with rapeseed oil increased the risk of lung cancer (OR = 1.56, 95% CI = 1.0-2.5) among non-smoking women. Among these women, occasional and frequent eye and throat irritation during cooking appeared to be associated with increased risk of lung cancer (ORs = 1.00, 1.42, 2.28, p trend < 0.01), whereas, increasing level of smokiness during cooking did not appear to affect risk.CONCLUSIONS: There is a suggestion that coal used for heating, environmental tobacco smoke, and cooking oil fumes contribute to the risk of lung cancer in this rural area of China.

Characterization of ATM mutations in 41 Nordic families with ataxia telangiectasia

The Ataxia Telangiectasia Mutation (ATM) gene is mutated in the rare recessive syndrome Ataxia Telangiectasia (AT), which is characterized by cerebellar degeneration, immunodeficiency, and cancer predisposition. In this study, 41 AT families from Denmark, Finland, Norway, and Sweden were screened for ATM mutations. The protein truncation test (PTT), fragment length and heteroduplex analyses of large (0.8-1.2 kb) cDNA fragments were used. In total, 67 of 82 (82%) of the disease-causing alleles were characterized. Thirty-seven unique mutations were detected of which 25 have not previously been reported. The mutations had five different consequences for the ATM transcript: mutations affecting splicing (43%); frameshift mutations (32%); nonsense mutations (16%); small in-frame deletions (5%); and one double substitution (3%). In 28 of the probands mutations were found in both alleles, in 11 of the probands only one mutated allele was detected, and no mutations were detected in two Finnish probands. One-third of the probands (13) were homozygous, whereas the majority of the probands (26) were compound heterozygote with at least one identified allele. Ten alleles were found more than once; one Norwegian founder mutation constituted 57% of the Norwegian alleles. Several sequence variants were identified, none of them likely to be disease-causing. Some of them even involved partial skipping of exons, leading to subsequent truncation of the ATM protein.

A pooled analysis of case-control studies of thyroid cancer. I. Methods

OBJECTIVE

Because the etiology of thyroid cancer is not well described, we conducted a pooled analysis of all published case-control studies, as well as two identified unpublished studies. This paper describes the major characteristics of the 14 studies included in the analysis, as well as the statistical methods employed. Four studies were conducted in the United States (1 each in Washington State, California, Connecticut and Hawaii), 8 in Europe (3 in Sweden, 2 in Norway, 1 in Switzerland, 1 in Italy and 1 in Greece), and 2 in Asia (1 in China and 1 in Japan).

METHODS

The original datasets were obtained and restructured in a uniform format. Data on socio-demographic characteristics, anthropometric measures, smoking and alcohol consumption, history of benign thyroid diseases and of other selected medical conditions and treatments, family history of cancer and of benign thyroid conditions, occupation, residence in endemic goitre areas, and dietary habits were analyzed. For women, we also analyzed menstrual and reproductive factors and use of female hormones. Radiotherapy and, in Japan, exposure to the A-bombs were considered as potential confounding factors.

RESULTS

A total of 2,725 cases (2,247 females and 478 males) and 4,776 controls (3,699 females and 1,077 males) were included in this study. Of the cases, 79% were classified as papillary thyroid carcinomas, 14% as follicular, 2% medullary, 1% anaplastic, 1% other histologies, and 3% histological type unknown. Each of the datasets was checked for outliers and consistency. Data were analysed separately by study center, gender, and the two major histologic types (papillary, follicular). Frequency tables and simple statistics were computed for each variable under study. Conditional logistic regression was used to compute odds ratios. For matched studies, the original matching was preserved, whereas, for unmatched ones, five-year age groups were used for matching. Study-specific analyses were computed, and then the data from all the studies were pooled conditioning on study. Heterogeneity between studies, geographic areas and study designs was assessed, and the modifying effect of age was also evaluated.

Radon measurements in underground dwellings from two prefectures in China

Radon, an established lung carcinogen, remains the single most important environmental radiation exposure. Yet, an excess of lung cancer from breathing radon in homes has not been consistently demonstrated in studies conducted to date. To address several major problems that have hindered previous studies of lung cancer and radon in homes, we have embarked upon a lung cancer case-control study in Gansu Province, China, where a substantial proportion of the population live in underground dwellings. In this paper, we report on results of a pilot study in which radon measurements were made for 3 days in the summer in 40 homes under normal occupancy conditions using short-term E-PERM detectors and for 6 months from February through August in 49 homes using long-term alpha-track detectors. Useable E-PERM data were obtained from 38 homes and useable alpha-track data from 47 homes. For both types of detectors, measurements were approximately log-normally distributed. Arithmetic and geometric means were 233 and 185 Bq m-3 (range 74-1,590 Bq m-3) for E-PERM measurements and 165 and 158 Bq m-3 (range 74-592 Bq m-3) for alpha-track measurements, respectively; 68% of E-PERM measured homes and 55% of alpha-track measured homes exceeded 148 Bq m-3. Alpha-track measurements made at the entry, middle, and rear areas of the underground dwellings did not differ significantly (arithmetic means of 168, 162, and 165 Bq m-3 with standard deviations 63, 73, and 48, respectively), which suggests that air circulation may be minimal. The underground dwellings measured in the pilot study had high radon levels and the underground dwellers may provide an excellent population for studying indoor radon and risk of lung cancer.

Failure to thrive: diagnostic yield of hospitalisation

Review of hospital records of 122 infants, aged between 1 and 25 months, admitted to a teaching hospital with the diagnosis of failure to thrive but without an underlying disease apparent at admission, showed that about one-third of them had no diagnosis after evaluation. Thirty-two per cent were thought to have a social or environmental explantation for poor growth, and 31% were given a specific organic or physiological diagnosis. Of the last group, 2 out 3 were diagnosed as having either gastro-oesophageal reflux or non-specific chronic diarrhoea. Vomiting was often associated with organic or structural disease. On average about 40 laboratory tests and x-ray films were performed per infant, but only 0.8% of all tests showed an abnormality which contributed to the diagnosis of the cause of failure to thrive. Our results stress the importance of social and environmental factors as basic causes of failure to thrive, and suggest that admission to hospital and laboratory testing is unlikely to lead to a specific organic diagnose in a child whose failure to thrive is unexplained after careful history taking and a physical examination.