Can We Miniaturize CT Technology for a Successful Mobile Stroke Unit Roll-Out?

Mortality from stroke remains high in Australia, especially for patients located outside the metropolitan cities. This is because they have limited access to specialized stroke facilities for optimal stroke treatment. Mobile stroke units have the capability to take CT scanners out to the patient however current CT commercial scanner designs are large and heavy. As such, this paper aims to design and develop a lightweight CT scanner for use in a mobile stroke unit (either road-based or air-based ambulance) to bring healthcare solution to patients in the rural and remote areas. We used the engineering design optimization approach to redesign and reduce the weight of the existing CT scanner with without compromised it structural performance. We managed to reduce the weight the CT scanner by three-fold while reducing design costs by allowing numerous simulations to be performed using computer software to achieve our design goals. The results are not only useful to optimize CT scanner structure to retrofit on a mobile stroke unit, but also bring the medical device solution to the market and support scalable solution to the larger community. Such an advance will allow for improved equity in healthcare whereby patients can be treated irrespective of location.

Applying Mendelian randomization to appraise causality in relationships between smoking, depression and inflammation

Smoking, inflammation and depression commonly co-occur and may be mechanistically linked. However, key questions remain around the direction of association and the influence of residual confounding. We aimed to characterize the association between lifetime smoking and depression, as well as to assess the role that genetically-predicted C-reactive protein (CRP) level, (an archetypal generalized inflammatory marker) and/or IL-6 activity, as a potential explanation for this association. We performed inverse variance weighted Mendelian randomization (MR) analyses using recently published summary-level GWAS data for lifetime smoking index, CRP levels, and depression. A subset of inflammatory-related genetic variants from the lifetime smoking GWAS were also used to assess the potential inflammatory causal pathways between smoking and depression. The analysis indicated reciprocal relationships of lifetime smoking with depression (ORSmk-Dep = 2.01, 95% CI 1.71-2.37, p < 0.001; ORDep-Smk = 1.09, 95% CI 1.06-1.13, p < 0.001), CRP levels and IL-6 activity (ORSmk-CRP = 1.40, 95% CI 1.21-1.55, p < 0.001; ORCRP-Smk = 1.03, 95% CI 1.02-1.05, p < 0.001, ORIL-6/CRP-Smk = 1.06 (1.03-1.09), p < 0.001). These associations were also supported by the majority of the robust MR methods performed. We did not find evidence for a reciprocal relationship between CRP levels (using > 500 genetic instruments for CRP) and depression (ORCRP-Dep = 1.01, 95% CI 0.99-1.04; ORDep-CRP = 1.03, 95% CI 0.99-1.07). We observed little variation in the IVW estimates between smoking and depression when we limited the genetic variants assessed to those related to measures of generalized inflammation, but we found evidence for an attenuation of the smoking-depression association in multivariable mendelian randomization when adjusting for IL-6 activity, suggesting that the IL-6 pathway may be at least in part responsible for the association of smoking and depression. Our study supports potential bidirectional causal associations between lifetime smoking and depression which may be at least in part explained by the IL-6 signalling pathway. The IL-6 pathway may represent a putative therapeutic target for smoking and to mitigate the effects of smoking on depression.

Abstract S2-03: Does BRCA status affect outcome in young breast cancer patients? Results from the prospective study of outcomes in sporadic and hereditary breast cancer (POSH)

Background

Germline mutations in BRCA1/2 account for ∼3% of breast cancer cases but &gt;10% of young patients who present with triple negative (TN) breast cancer. Young age at diagnosis is also associated with an increased risk of recurrence and inferior survival compared to older patients. Numerous publications describe an increased incidence of adverse biological features in tumours from young breast cancer patients; however it is unclear whether these fully explain the poor outcome.

The effect of carrying a BRCA1/2 mutation on the prognosis of breast cancer remains controversial with retrospective studies reporting better, similar and worse outcomes for mutation carriers compared to patients with sporadic tumours. BRCA carriers could feasibly have enhanced or reduced sensitivity to certain chemotherapeutics; however retrospective studies are problematic due to missing data and biased ascertainment. POSH is multicentre prospective observational cohort study designed to investigate factors which affect prognosis in young breast cancer patients (Copson et al, JNCI, 2013). Here we report the pathology, treatment and outcome of patients with TN tumours as a preliminary analysis to determine the impact of a germline BRCA1 mutation on survival. The whole cohort analysis including BRCA1 and BRCA2 is in progress.

Methods

2956 patients aged ≤40 at breast cancer diagnosis were recruited from 127 UK oncology centres between 2000 and 2008. Patient characteristics, family history, risk factors, tumour pathology and treatment information, and blood DNA were collected at recruitment. Follow-up data were collected at 6 and 12 months, then annually. Summary statistics were used to describe patients by BRCA1 status. Kaplan-Meier estimates were used to describe univariate survival data.

Results

BRCA1 status is currently available for 542 patients with TN tumours. Pathogenic BRCA1 mutations were identified in 122 patients (BRCA1+); 420 had no BRCA1 mutation (BRCA1-). BRCA1+ were younger than BRCA1- (median age 34 vs 36 years, p&lt;0.001) and more likely to have a positive family history (p&lt;0.001). There were no significant differences between BRCA1+ vs BRCA1- for: median tumour size (20.8mm vs 23.0mm); tumour grade distribution (95.8% grade 3 vs 93.6%); nodal involvement (35.2% node positive vs 39.9%); or presence of metastases at diagnosis (0.0% vs 1.0%).

Median follow-up was 7.3 years. Overall survival of patients with stage 1-3 disease treated with anthracycline +/- taxane neoadjuvant chemotherapy (n=538; 151 deaths) was better for BRCA1+ vs BRCA1- (79.1% vs 73.6% at 5-yrs; HR[95%CI]=0.84[0.57,1.25],p=0.388). Distant disease-free survival (DDFS) was also higher for BRCA1+ (5-yr DDFS 76.1% vs 71.5%; HR[CI]=0.92[0.63,1.35], p=0.682). Moreover, survival after first distant relapse was better for BRCA1+ patients (41.9% vs 36.8% at 1-yr; HR[CI]=0.78[0.51,1.18], p=0.233).

Conclusions

Our prospective data show better survival in young BRCA1+ patients with early TN breast cancer treated with anthracycline/-taxane chemotherapy than BRCA1- patients. However, the difference between the groups was not significant in this partial sample. Results for the whole cohort will be available by the time of the meeting.

Citation Format: Eccles DM, Copson ER, Maishman T, Tapper W, Cutress R, Gerty S, Stanton L, Altman DG, Durcan L, Simmonds P, Decker B, Allen J, Luccarini C, Easton D, Dunning A, POSH Steering Group and Collaborators. Does BRCA status affect outcome in young breast cancer patients? Results from the prospective study of outcomes in sporadic and hereditary breast cancer (POSH) [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr S2-03.

Functional variants at the 11q13 risk locus for breast cancer regulate cyclin D1 expression through long-range enhancers

Analysis of 4,405 variants in 89,050 European subjects from 41 case-control studies identified three independent association signals for estrogen-receptor-positive tumors at 11q13. The strongest signal maps to a transcriptional enhancer element in which the G allele of the best candidate causative variant rs554219 increases risk of breast cancer, reduces both binding of ELK4 transcription factor and luciferase activity in reporter assays, and may be associated with low cyclin D1 protein levels in tumors. Another candidate variant, rs78540526, lies in the same enhancer element. Risk association signal 2, rs75915166, creates a GATA3 binding site within a silencer element. Chromatin conformation studies demonstrate that these enhancer and silencer elements interact with each other and with their likely target gene, CCND1.

Bulky mediastinal Hodgkin's disease management and prognosis

Of a total of 235 Stage I and II Hodgkin's disease patients treated between 1970 and 1979, 103 (43.8 per cent) had mediastinal involvement in 45 of whom the disease was bulky and in 58 non-bulky. This report concentrates on bulky disease patients of whom 45 per cent did not relapse after therapy and 71 per cent are alive. Patients with mediastinal disease were treated with radiotherapy (63), sequential chemo-radiotherapy (37) or chemotherapy alone (3). In the radiotherapy group the relapse rate for bulky disease was significantly higher (65 per cent) than for non-bulky disease (44 per cent) (P less than 0.05) although there was no significant difference in survival. Neither relapse rate nor survival differed significantly in bulky disease patients treated with radiotherapy compared with combined chemo-radiotherapy although there was a 20 per cent difference in relapse-free survival rate in favour of the combined treatment group at five years. Treatments were not allocated randomly and the chemo-radiotherapy group contained a disproportionate number of patients with adverse features (greater than 3 node areas involved, limited lung extension) compared with the irradiated group; 11/25 and 2/17 respectively. The number of lymph node areas involved appeared to influence the relapse rate in the radiotherapy group. There was no correlation between mediastinal mass size and number of node areas involved suggesting that these two features may be independent prognostic factors.

Germline BRCA1 mutations increase prostate cancer risk

BACKGROUND

Prostate cancer (PrCa) is one of the most common cancers affecting men but its aetiology is poorly understood. Family history of PrCa, particularly at a young age, is a strong risk factor. There have been previous reports of increased PrCa risk in male BRCA1 mutation carriers in female breast cancer families, but there is a controversy as to whether this risk is substantiated. We sought to evaluate the role of germline BRCA1 mutations in PrCa predisposition by performing a candidate gene study in a large UK population sample set.

METHODS

We screened 913 cases aged 36–86 years for germline BRCA1 mutation, with the study enriched for cases with an early age of onset. We analysed the entire coding region of the BRCA1 gene using Sanger sequencing. Multiplex ligation-dependent probe amplification was also used to assess the frequency of large rearrangements in 460 cases.

RESULTS

We identified 4 deleterious mutations and 45 unclassified variants (UV). The frequency of deleterious BRCA1 mutation in this study is 0.45%; three of the mutation carriers were affected at age 65 years and one developed PrCa at 69 years. Using previously estimated population carrier frequencies, deleterious BRCA1 mutations confer a relative risk of PrCa of ~3.75-fold, (95% confidence interval 1.02–9.6) translating to a 8.6% cumulative risk by age 65.

CONCLUSION

This study shows evidence for an increased risk of PrCa in men who harbour germline mutations in BRCA1. This could have a significant impact on possible screening strategies and targeted treatments.

Genetic variants associated with predisposition to prostate cancer and potential clinical implications

Prostate cancer is the commonest cancer in the developed world. There is an inherited component to this disease as shown in familial and twin studies. However, the discovery of these variants has been difficult. The emergence of genome-wide association studies has led to the identification of over 46 susceptibility loci. Their clinical utility to predict risk, response to treatment, or treatment toxicity, remains undefined. Large consortia are needed to achieve adequate statistical power to answer these genetic-clinical and genetic-epidemiological questions. International collaborations are currently underway to link genetic with clinical/epidemiological data to develop risk prediction models, which could direct screening and treatment programs.

Hand pattern indicates prostate cancer risk

BACKGROUND

The ratio of digit lengths is fixed in utero, and may be a proxy indicator for prenatal testosterone levels.

METHODS

We analysed the right-hand pattern and prostate cancer risk in 1524 prostate cancer cases and 3044 population-based controls.

RESULTS

Compared with index finger shorter than ring finger (low 2D : 4D), men with index finger longer than ring finger (high 2D : 4D) showed a negative association, suggesting a protective effect with a 33% risk reduction (odds ratio (OR) 0.67, 95% confidence interval (CI) 0.57-0.80). Risk reduction was even greater (87%) in age group <60 (OR 0.13, 95% CI 0.09-0.21).

CONCLUSION

Pattern of finger lengths may be a simple marker of prostate cancer risk, with length of 2D greater than 4D suggestive of lower risk.

Elevated expression of Ki-67 identifies aggressive prostate cancers but does not distinguish BRCA1 or BRCA2 mutation carriers

Prostate cancers in men with germline BRCA1 and BRCA2 mutations are more aggressive than morphologically similar cancers in men without these mutations. This study was performed to test the hypothesis that enhanced expression of Ki-67, as a surrogate of cell proliferation, is a characteristic feature of prostate cancers occurring in BRCA1 or BRCA2 mutation carriers. The study cohort comprised 20 cases of prostate cancer in mutation carriers and 126 control sporadic prostate cancers. Of the combined sample cohort, 65.7% stained only within malignant tissues while 0.7% stained in both malignant and benign tissues (p<0.001). Significantly increased expression of Ki-67 occurred in prostate cancers with higher Gleason score (p<0.001). Elevated Ki-67 expression was identified in 71% of prostate cancers in BRCA1 or BRCA2 mutation carriers and in 67% of the sporadic controls (p>0.5). Similar results were obtained when the data were analysed using a threshold set at 3.5 and 7.1%. This study shows that elevated expression of Ki-67 is associated both with aggressive prostate cancers and with high Gleason score irrespective of whether their occurrence is against a background of BRCA1 or BRCA2 mutations or as sporadic disease. The data suggest that, since elevated Ki-67 does not distinguish prostate cancers occurring in BRCA1 or BRCA2 mutation carriers from sporadic prostatic malignancies, the effects of these genetic mutations are probably independent. While all prostate cancers occurring in the presence of BRCA germline mutations are clinically aggressive, their potentially different phenotypes consistently involve maximal rates of cell proliferation.

A Novel Tumour-Based Test To Identify Breast Cancer Due to BRCA1 and BRCA2 Mutations

Background: Family history and young onset are the usual indicators of an underlying genetic predisposition to breast cancer development. BRCA1 associated breast tumours are more likely to be ER negative and express “basal” markers, however most patients with ER negative/ basal marker positive breast cancers (especially young onset) do not have inherited BRCA1 mutations. BRCA1 and BRCA2 gene carriers may have novel treatment options available and may need to consider future cancer prevention strategies. Genetic counselling and germline mutation analysis remains a relatively expensive option that is not appropriate for most breast cancer patients.Aim: To design a sensitive and specific pathology based predictor that would improve identification of BRCA1 and 2 gene carriers.Method: We assembled a training panel of breast cancer tumour blocks from 67 BRCA1, 71 BRCA2 associated and 105 sporadic young onset cases (≤ 40 years at diagnosis). All gene carriers were diagnosed before 50 years and were matched to sporadic cases for ER status. Tissue micro arrays (TMAs) were assembled and subjected to immunohistochemical analysis with a panel of 18 antibodies. DNA was extracted from micro dissected tumour tissue and matched patient lymphocytes and subjected to high resolution tiling path microarray-based Comparative Genomic Hybridisation (aCGH). Using robust statistical approaches, regions significantly differentially lost, gained or amplified in BRCA1, BRCA2 and controls were identified. Probes for chromogenic in situ hybridisation (CISH) for amplified regions were generated.Results: Two differentially amplified clones in BRCA1 cases designated P1 at 3q25.31 and P2 at 3q25.2 and one in BRCA2 cases, P3 at 20q13.13, were identified and amplifications validated in the training set using CISH. Logistic regression analysis of the panel comprising CISH and IHC markers was used to develop the best predictor. The best predictor for BRCA1 gene carriers was a combination of P1, ER and HER2. This combination outperformed all combinations of immunohistochemical markers, including ER and basal markers; the Positive Predictive Value (PPV) was 87.5% and NPV 92% giving a Receiver Operator Characteristic (ROC) curve with an AUC of 0.92 (CI 0.88-0.97). The BRCA2 signature panel is currently being evaluated. These BRCA1 and BRCA2 predictor panels are being validated in a new set of TMAs comprising 223 tumours from the POSH study1.Conclusion: This tumour based predictor for BRCA1 and BRCA2 carriers may prove useful to identify gene carriers at low a priori chance of having a mutation, to direct BRCA1/2 targeted treatment approaches and to identify familial non BRCA1/2 cases that may be suitable for new gene discovery studies.1. Eccles D et al. BMC Cancer 2007; 7(1):160.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 5032.

Diagnostic radiation procedures and risk of prostate cancer

Exposure to ionising radiation is an established risk factor for many cancers. We conducted a case-control study to investigate whether exposure to low dose ionisation radiation from diagnostic x-ray procedures could be established as a risk factor for prostate cancer. In all 431 young-onset prostate cancer cases and 409 controls frequency matched by age were included. Exposures to barium meal, barium enema, hip x-rays, leg x-rays and intravenous pyelogram (IVP) were considered. Exposures to barium enema (adjusted odds ratio (OR) 2.06, 95% confidence interval (CI) 1.01-4.20) and hip x-rays (adjusted OR 2.23, 95% CI 1.42-3.49) at least 5 years before diagnosis were significantly associated with increased prostate cancer. For those with a family history of cancer, exposures to hip x-rays dating 10 or 20 years before diagnosis were associated with a significantly increased risk of prostate cancer: adjusted OR 5.01, 95% CI 1.64-15.31 and adjusted OR 14.23, 95% CI 1.83-110.74, respectively. Our findings show that exposure of the prostate gland to diagnostic radiological procedures may be associated with increased cancer risk. This effect seems to be modified by a positive family history of cancer suggesting that genetic factors may play a role in this risk association.

Prostate cancer in male BRCA1 and BRCA2 mutation carriers has a more aggressive phenotype

There is a high and rising prevalence of prostate cancer (PRCA) within the male population of the United Kingdom. Although the relative risk of PRCA is higher in male BRCA2 and BRCA1 mutation carriers, the histological characteristics of this malignancy in these groups have not been clearly defined. We present the histopathological findings in the first UK series of BRCA1 and BRCA2 mutation carriers with PRCA. The archived histopathological tissue sections of 20 BRCA1/2 mutation carriers with PRCA were collected from histopathology laboratories in England, Ireland and Scotland. The cases were matched to a control group by age, stage and serum PSA level of PRCA cases diagnosed in the general population. Following histopathological evaluation and re-grading according to current conventional criteria, Gleason scores of PRCA developed by BRCA1/2 mutation carriers were identified to be significantly higher (Gleason scores 8, 9 or 10, P=0.012) than those in the control group. Since BRCA1/2 mutation carrier status is associated with more aggressive disease, it is a prognostic factor for PRCA outcome. Targeting screening to this population may detect disease at an earlier clinical stage which may therefore be beneficial.

A physical analysis of the Y chromosome shows no additional deletions, other than Gr/Gr, associated with testicular germ cell tumour

Testicular germ cell tumour (TGCT) is the most common malignancy in men aged 15-45 years. A small deletion on the Y chromosome known as 'gr/gr' was shown to be associated with a two-fold increased risk of TGCT, increasing to three-fold in cases with a family history of TGCT. Additional deletions of the Y chromosome, known as AZFa, AZFb and AZFc, are described in patients with infertility; however, complete deletions of these regions have not been identified in TGCT patients. We screened the Y chromosome in a series of TGCT cases to evaluate if additional deletions of Y were implicated in TGCT susceptibility. Single copy Y chromosome STS markers with an average inter-marker spacing of 128 kb were examined in constitutional DNA of 271 index TGCT patients. Three markers showed evidence of deletions, sY1291, indicative of 'gr/gr' (eight out of 271; 2.9%), Y-DAZ3 contained within 'gr/gr' (21 out of 271; 7.7%) and a single deletion of the marker G66152 was identified in one TGCT case. No other markers demonstrated deletions. While several regions of the Y chromosome are known to be deleted and associated with infertility, our study provides no evidence to suggest regions of Y deletion, other than 'gr/gr', are associated with susceptibility to TGCT in UK patients.

Cost-effectiveness of screening with contrast enhanced magnetic resonance imaging vs X-ray mammography of women at a high familial risk of breast cancer

Contrast enhanced magnetic resonance imaging (CE MRI) is the most sensitive tool for screening women who are at high familial risk of breast cancer. Our aim in this study was to assess the cost-effectiveness of X-ray mammography (XRM), CE MRI or both strategies combined. In total, 649 women were enrolled in the MARIBS study and screened with both CE MRI and mammography resulting in 1881 screens and 1–7 individual annual screening events. Women aged 35–49 years at high risk of breast cancer, either because they have a strong family history of breast cancer or are tested carriers of a BRCA1, BRCA2 or TP53 mutation or are at a 50% risk of having inherited such a mutation, were recruited from 22 centres and offered annual MRI and XRM for between 2 and 7 years. Information on the number and type of further investigations was collected and specifically calculated unit costs were used to calculate the incremental cost per cancer detected. The numbers of cancer detected was 13 for mammography, 27 for CE MRI and 33 for mammography and CE MRI combined. In the subgroup of BRCA1 (BRCA2) mutation carriers or of women having a first degree relative with a mutation in BRCA1 (BRCA2) corresponding numbers were 3 (6), 12 (7) and 12 (11), respectively. For all women, the incremental cost per cancer detected with CE MRI and mammography combined was £28 284 compared to mammography. When only BRCA1 or the BRCA2 groups were considered, this cost would be reduced to £11 731 (CE MRI vs mammography) and £15 302 (CE MRI and mammography vs mammography). Results were most sensitive to the unit cost estimate for a CE MRI screening test. Contrast-enhanced MRI might be a cost-effective screening modality for women at high risk, particularly for the BRCA1 and BRCA2 subgroups. Further work is needed to assess the impact of screening on mortality and health-related quality of life.

A prospective study of neurofibromatosis type 1 cancer incidence in the UK

Neurofibromatosis type 1 (NF1) is an autosomal dominant condition affecting around one in 3000 live births. The manifestations of this condition are extremely variable, even within families, and genetic counselling is consequently difficult with regard to prognosis. Individuals with NF1 are acknowledged to be at increased risk of malignancy. Several studies have previously attempted to quantify this risk, but have involved relatively small study populations. We present prospective data from 448 individuals with NF1 with a total of 5705 years of patient follow-up. These data have been collected via the UK NF1 association for patients. Demographic information on the affected individuals was cross-referenced with UK cancer registry data by the UK Office of National Statistics. The overall risk of cancer was 2.7 times higher in this cohort of NF1 patients than in the general population (95% confidence interval (CI) 1.9–3.7). The cumulative risk of a malignancy by age 50 years was 20% (95% CI 14–29%); beyond this age, the risk of cancer was not significantly elevated (P=0.27). The most frequent types of cancer were connective tissue (14% risk by age 70, 95% CI 7.8–24%) and brain tumours (7.9, 95% CI 3.9–16%). There was no statistically significant excess of cancers at other sites (P=0.22).

Somatic mutations of KIT in familial testicular germ cell tumours

Somatic mutations of the KIT gene have been reported in mast cell diseases and gastrointestinal stromal tumours. Recently, they have also been found in mediastinal and testicular germ cell tumours (TGCTs), particularly in cases with bilateral disease. We screened the KIT coding sequence (except exon 1) for germline mutations in 240 pedigrees with two or more cases of TGCT. No germline mutations were found. Exons 10, 11 and 17 of KIT were examined for somatic mutations in 123 TGCT from 93 multiple-case testicular cancer families. Five somatic mutations were identified; four were missense amino-acid substitutions in exon 17 and one was a 12 bp in-frame deletion in exon 11. Two of seven TGCT from cases with bilateral disease carried KIT mutations compared with three out of 116 unilateral cases (P=0.026). The results indicate that somatic KIT mutations are implicated in the development of a minority of familial as well as sporadic TGCT. They also lend support to the hypothesis that KIT mutations primarily take place during embryogenesis such that primordial germ cells with KIT mutations are distributed to both testes.

Supportive care management of brain metastases: what is known and what we need to know. Conference proceedings of the National Cancer Institute of Canada (NCIC) Workshop on Symptom Control in Radiation Oncology

OBJECTIVES

To review the results of published randomised controlled trials in the treatment of brain metastases and, from the knowledge gained from these trials, to identify potential study questions.

MATERIALS AND METHODS

The literature was searched for randomised controlled trials that dealt with the management of brain metastases. Potential research questions were identified on the basis of the results of the literature review.

RESULTS

A number of research questions were identified. In the context of the NCIC Symptom Control Group, a trial of supportive care alone vs supportive care and whole-brain radiotherapy (WBRT) in a subset of patients with the diagnosis of brain metastases was deemed to be of highest priority. We discussed a number of issues relating to the feasibility of such a trial.

CONCLUSIONS

The optimal management of brain metastases remains elusive. Despite the results of numerous randomised controlled trials, many questions remain unanswered. The magnitude of benefit using WBRT above supportive care alone is uncertain. A trial of supportive care alone vs supportive care and WBRT may be successful once target population, feasibility and methodological issues are thoroughly solved.

Association between leptin receptor gene polymorphisms and early-onset prostate cancer

OBJECTIVE

To report a case-control study examining the relationship between polymorphisms in the leptin receptor (OBR) gene and the development of young-onset prostate cancer, because epidemiological studies report that prostate cancer risk is associated with animal fat intake, and thus we investigated if this association occurs via this genetic mechanism.

PATIENTS, SUBJECTS AND METHODS

The Lys109Arg (OBR1) and Gln223Arg (OBR2) polymorphisms in the coding region of OBR were studied in blood DNA from 271 patients with prostate cancer aged < 56 years at diagnosis and 277 geographically matched control subjects. Cases were collected through the Cancer Research UK/British Prostate Group Familial Prostate Cancer Study. Blood DNA was genotyped using the polymerase chain reaction and a restriction enzyme digest.

RESULTS

There was no statistically significant association between the OBR genotype and prostate cancer risk; men homozygous for 109Arg genotype had a slightly increased risk for prostate cancer, with a relative risk (95% confidence interval) of 1.36 (0.65-2.85), and those homozygous for the 223Arg allele had some reduction in prostate cancer risk, at 0.82 (0.58-1.26), but neither was statistically significant.

CONCLUSION

This case-control study showed no significant association between leptin receptor gene polymorphisms and the risk of young-onset prostate cancer, suggesting that genetic variations in OBR are unlikely to have a major role in the development of early-onset prostate cancer in the UK.

Apoptosis, ageing and cancer susceptibility

We have previously shown that peripheral blood lymphocytes (PBL) from individuals carrying a germline TP53 mutation show a dramatically reduced apoptotic response to radiation. As part of a study of this phenomenon, we also investigated apoptotic response in a series of breast cancer patients lacking TP53 mutations and in a control group of individuals without cancer. There was a significant reduction in mean apoptotic response with increasing age in all groups. These findings are consistent with a number of studies in rodents, which have demonstrated a reduction in DNA damage-induced apoptosis with increasing age. In addition, after adjusting for age, breast cancer patients showed significantly reduced apoptotic responses compared with normal controls (P=0.002). The odds ratio for breast cancer in women with an apoptotic response of <35%, compared with women with a response of >49%, was 6.42 (95% CI 1.68-24.6). The data further support the hypothesis that a reduction in apoptotic response to DNA damage with increasing age may play a significant role in the age-related increase in cancer.

Apolipoprotein E4 is only a weak predictor of dementia and cognitive decline in the general population

BACKGROUND

Apolipoprotein E (APOE) polymorphisms are unequivocally associated with risk for Alzheimer's disease (AD). It is crucial to understand how this genetic factor affects dementia risk in the general population, as well as in narrowly diagnosed, selected, patient groups.

METHODS

We assessed the cross sectional association between APOE genotype and dementia status in a community based sample, the MRC Cognitive Function and Ageing Study (MRC CFAS). In addition, we tested the effects of APOE genotypes on the differences in MMSE scores between the first and third assessment waves (about six years apart), an index of cognitive decline.

RESULTS

The APOE epsilon4 allele conferred increased risk for dementia (OR=1.5, 95% CI=1.1 to 2.2) compared to epsilon3 in the MRC CFAS sample. Compared with APOE epsilon3/epsilon 3 subjects, those with the epsilon3/epsilon4 genotypes were not at significantly higher risk for dementia (OR=1.1, 95% CI=0.6 to 1.9), although epsilon4/epsilon4 subjects were (OR= 3.8, 95% CI=1.0 to 14.0). Risk estimates were not different between men and women. Notably, our risk estimates for dementia were significantly lower than those reported for a diagnosis of Alzheimer's disease. MMSE scores at wave 3 and the difference in MMSE between baseline and at the third assessment wave were not different across APOE genotypes.

INTERPRETATION

The APOE epsilon4 allele is a weaker predictor for dementia in the general population than for AD. This may be because dementia can be caused by non-AD pathological processes and because most prevalent dementia occurs at an age when the APOE epsilon4 effect on AD risk (and therefore dementia) has started to decline.

Alzheimer disease is not associated with polymorphisms in the angiotensinogen and renin genes

Hypertension has been implicated as a risk factor for Alzheimer disease (AD) and dementia in epidemiological studies of humans. It is thus possible that there are common genetic determinants for hypertension and AD. Epidemiological, clinical, and experimental data suggest that the renin-angiotensin-aldosterone system is a critical regulator of blood pressure. The presence of an MboI site in an RFLP in the renin gene and the Thr at the Met/Thr polymorphism at codon 235 (M235T) of the angiotensinogen gene have been reported to be associated with hypertension. These variants were studied in autopsy-confirmed AD cases and matched controls from the U.K. While no association was detected with the renin polymorphism, a weak deleterious effect was observed in cases homozygous for the angiotensinogen Thr allele. However, this association was not observed in a French cohort of clinically diagnosed AD cases and controls, suggesting that the initial observation was a type I error. Thus, these polymorphisms are unlikely to be associated with AD risk.

Genome-wide linkage disequilibrium mapping of late-onset Alzheimer's disease in Finland

BACKGROUND

AD is a complex neurodegenerative disorder comprising several disease-associated chromosome loci. To find novel susceptibility genes for late-onset AD, a population-based genome-wide search using linkage disequilibrium (LD) mapping approach has been performed.

METHOD

Forty-seven patients with late-onset AD and 51 age-matched control subjects were carefully chosen from the same geographic area in eastern Finland, where the population is descended mainly from a small group of original founders. These subjects were initially genotyped with 366 polymorphic microsatellite markers, and a follow-up analysis was performed with additional microsatellite markers for those chromosome loci found to be associated with AD.

RESULTS

Initial genome-wide screening revealed 21 chromosomal loci significantly associated with AD in addition to the 13q12 locus described previously. Subsequent comparison of single-allele frequencies of the microsatellite markers in the AD and control groups indicated the presence both of possible risk alleles (odds ratio [OR] > 1) and of possible protective alleles (OR < 1). Screening of the LD regions with additional microsatellite markers revealed seven chromosomal loci where more than one microsatellite marker was associated with AD (1p36.12, 2p22.2, 3q28, 4p13, 10p13, 18q12.1, and 19p13.3) in addition to the 13q12 locus.

CONCLUSIONS

These genome-wide LD screening data suggest that several AD-associated chromosomal loci exist, which may encompass novel susceptibility genes for late-onset AD. Therefore, extensive screening of the genes located in the vicinity of these LD regions is necessary to elucidate their role in AD.

"War stories": AIDS prevention and the street narratives of drug users

The day-to-day discourse of illicit drug users is replete with stylized narratives of street experience. These "war stories," as they are popularly known, are shared among drug users as they hustle for money, purchase drugs, get high, and hang out in diverse street locations. Drug-user narratives, which describe complex adventures and grave suffering, are primary ethnographic sources of information about patterns of drug consumption and risk behaviors. Importantly, in the time of AIDS, street narratives provide a much-needed window on the generally hidden lives of socially marginalized street drug users. As part of an effort to put the analysis of drug-user war stories to use in HIV prevention, in this article the authors analyze a corpus of street narratives told to members of an HIV-prevention research team in Hartford, Connecticut.

Evidence for further breast cancer susceptibility genes in addition to BRCA1 and BRCA2 in a population-based study

We used data from a population based series of breast cancer patients to investigate the genetic models that can best explain familial breast cancer not due to the BRCA1 and BRCA2 genes. The data set consisted of 1,484 women diagnosed with breast cancer under age 55 registered in the East Anglia Cancer registry between 1991-1996. Blood samples taken from the patients were analysed for mutations in BRCA1 and BRCA2. The genetic models were constructed using information on breast and ovarian cancer history in first-degree relatives and on the mutation status of the index patients. We estimated the simultaneous effects of BRCA1, BRCA2, a third hypothetical gene BRCA3, and a polygenic effect. The models were assessed by likelihood comparisons and by comparison of the observed numbers of mutations and affected relatives with the predicted numbers. BRCA1 and BRCA2 could not explain all the familial clustering of breast cancer. The best-fitting single gene model for BRCA3 was a recessive model with a disease allele frequency 24% and penetrance 42% by age 70. However, a polygenic model gave a similarly good fit. The estimated population frequencies for BRCA1 and BRCA2 mutations were similar under both recessive and polygenic models, 0.024 and 0.041%, respectively. A dominant model for BRCA3 gave a somewhat worse fit, although the difference was not significant. The mixed recessive model was identical to the recessive model and the mixed dominant very similar to the polygenic model. The BRCA3 genetic models were robust to the BRCA1 and BRCA2 penetrance assumptions. The overall fit of all models was improved when the known effects of parity on breast and ovarian cancer risks were included in the model-in this case a polygenic model fits best. These findings suggest that a number of common, low-penetrance genes with additive effects may account for the residual non-BRCA1/2 familial aggregation of breast cancer, but Mendelian inheritance of an autosomal recessive allele cannot be ruled out.

Relationship between glutathione S-transferase M1, P1 and T1 polymorphisms and early onset prostate cancer

There is evidence suggesting that polymorphic variations in the glutathione S-transferases (GSTs) are associated with cancer susceptibility. Inter-individual differences in cancer susceptibility may be mediated in part through polymorphic variability in the bioactivation and detoxification of carcinogens. The GSTs have been consistently implicated as cancer susceptibility genes in this context. The GST supergene family includes several loci with well characterized polymorphisms. Approximately 50% of the Caucasian population are homozygous for deletions in GSTM1 and approximately 20% are homozygous for deletions in GSTT1, resulting in conjugation deficiency of mutagenic electrophiles to glutathione. The GSTP1 gene has a polymorphism at codon 105 resulting in an Ile to Val substitution which consequently alters the enzymatic activity of the protein and this has been suggested as a putative high-risk genotype in various cancers. We investigated the relationship between GST polymorphisms and young onset prostate cancer in a case-control study. GSTM1, GSTT1 and GSTP1 genotypes were determined for 275 prostate cancer patients and for 280 geographically matched control subjects. We found no significant difference in the frequency of GSTM1 or GSTT1 null genotypes between cases and controls. GSTP1 genotype was, however, significantly associated with prostate cancer risk: the Ile/Ile homozygotes had the lowest risk and there was a trend in increasing the risk with the number of 105 Val alleles: Ile/Val odds ratio (OR)= 1.30 (95% FCI 0.99-1.69), Val/Val OR = 1.80 (95% FCI 1.11-2.91); Ptrend = 0.026. These results suggest that the GSTP1 polymorphism may be a risk factor for developing young onset prostate cancer. We also found that carrying more than one putative high-risk allele in the carcinogen metabolizing GST family was associated with an elevated risk for early onset prostate cancer (OR 2.48, 95% FCI 1.22-5.04, Ptrend = 0.017).

Genetic association of an LBP-1c/CP2/LSF gene polymorphism with late onset Alzheimer's disease

OBJECTIVES

The only locus unequivocally associated with late onset Alzheimer's disease (AD) risk is APOE. However, this locus accounts for less than half the genetic variance. A recent study suggested that the A allele of the 3'UTR biallelic polymorphism in the LBP-1c/CP2/LSF gene was associated with reduced AD risk. Samples were diagnosed predominantly by clinical rather than pathological criteria. We have sought to replicate this finding in a series of necropsy confirmed, late onset AD cases and non-demented controls.

METHODS

The 3'UTR polymorphism in the LBP-1c/CP2/LSF gene was typed in 216 necropsy confirmed AD cases and 301 non-demented controls aged >73 years.

RESULTS

We found different LBP-1c/CP2/LSF allele distributions in our AD cases and controls (p=0.048); the A allele was associated with reduced AD risk. The allele and genotype frequencies observed in our cases and controls were similar to those previously reported. No significant effects emerged when the data were adjusted for age, sex, or apoE epsilon4 carrier status.

CONCLUSIONS

Our data support LBP-1c/CP2/LSF as a candidate gene/risk factor for AD and provide justification for future studies to investigate the role of this gene in Alzheimer's disease.

The BACE gene: genomic structure and candidate gene study in late-onset Alzheimer's disease

Alzheimer's disease (AD) pathology is characterized by beta-amyloid plaques and neurofibrillary tangles. Studies of autosomal dominant early-onset AD mutations suggest that beta-amyloid overproduction is sufficient to cause AD. Recently, the BACE gene, which encodes beta-secretase, the rate limiting enzyme in beta-amyloid formation, has been identified. Since this gene is a strong candidate gene for late-onset AD because of its function, we have characterized its genomic organization and identified two polymorphisms. Neither of these polymorphisms were associated with AD risk in genetic association studies comparing autopsy-confirmed late-onset AD cases and age-matched non-demented controls. Thus, we find no evidence that this locus influences risk for late-onset AD.

Sibling risks in cancer: clues to recessive or X-linked genes?

A systematic analysis of cancer risks to offspring and to siblings of cancer cases was carried out based on the nation-wide Swedish Family-Cancer Database. For all 13 cancer sites examined, risks to both offspring and siblings of cases of cancer at the same site were significantly elevated. The relative risk to siblings was approximately 2 fold more than the offspring risk for cancers of the prostate, testis, kidney and bladder, suggesting that recessive or X-linked susceptibility genes may be important for these cancers. Risks to siblings of cases where a parent was also affected were increased >20 fold over population rates for colorectal, ovarian, prostate and renal cancer, and for leukaemia, consistent with the effects of rare high-risk susceptibility alleles.

Variation in cancer risks, by mutation position, in BRCA2 mutation carriers

Cancer occurrence in 164 families with breast/ovarian cancer and germline BRCA2 mutations was studied to evaluate the evidence for genotype-phenotype correlations. Mutations in a central portion of the gene (the "ovarian cancer cluster region" [OCCR]) were associated with a significantly higher ratio of cases of ovarian:breast cancer in female carriers than were mutations 5' or 3' of this region (P<.0001), extending previous observations. The optimal definition of the OCCR, as judged on the basis of deviance statistics, was bounded by nucleotides 3059-4075 and 6503-6629. The relative and absolute risks of breast and ovarian cancer associated with OCCR and non-OCCR mutations were estimated by a conditional likelihood approach, conditioning on the set of mutations observed in the families. OCCR mutations were associated both with a highly significantly lower risk of breast cancer (relative risk [RR] 0.63; 95% confidence interval (95% CI) 0.46-0.84; P=.0012) and with a significantly higher risk of ovarian cancer (RR = 1.88; 95% CI = 1.08-3.33; P=.026). No other differences in breast or ovarian cancer risk, by mutation position, were apparent. There was some evidence for a lower risk of prostate cancer in carriers of an OCCR mutation (RR = 0.52; 95% CI = 0.24-1.00; P=.05), but there was no evidence of a difference in breast cancer risk in males. By age 80 years, the cumulative risk of breast cancer in male carriers of a BRCA2 mutation was estimated as 6.92% (95% CI = 1.20%-38.57%). Possible mechanisms for the variation in cancer risk are suggested by the coincidence of the OCCR with the RAD51-binding domain.

High risk genes predisposing to prostate cancer development-do they exist?

There is evidence for genetic predisposition to prostate cancer. However, prostate cancer genes have been more difficult to find than genes for some of the other common cancers, such as breast and colon cancer. The reasons for this are discussed in this article and it is now becoming clear that prostate cancer is probably due to multiple genes, many of which are moderate or low penetrance. The advances in the Human Genome Project and technology, especially that of robotics, will help to overcome these problems. Prostate Cancer and Prostatic Diseases (2000) 3, 241-247

The extent of linkage disequilibrium in four populations with distinct demographic histories

The design and feasibility of whole-genome-association studies are critically dependent on the extent of linkage disequilibrium (LD) between markers. Although there has been extensive theoretical discussion of this, few empirical data exist. The authors have determined the extent of LD among 38 biallelic markers with minor allele frequencies >.1, since these are most comparable to the common disease-susceptibility polymorphisms that association studies aim to detect. The markers come from three chromosomal regions-1,335 kb on chromosome 13q12-13, 380 kb on chromosome 19q13.2, and 120 kb on chromosome 22q13.3-which have been extensively mapped. These markers were examined in approximately 1,600 individuals from four populations, all of European origin but with different demographic histories; Afrikaners, Ashkenazim, Finns, and East Anglian British. There are few differences, either in allele frequencies or in LD, among the populations studied. A similar inverse relationship was found between LD and distance in each genomic region and in each population. Mean D' is.68 for marker pairs <5 kb apart and is.24 for pairs separated by 10-20 kb, and the level of LD is not different from that seen in unlinked marker pairs separated by >500 kb. However, only 50% of marker pairs at distances <5 kb display sufficient LD (delta>.3) to be useful in association studies. Results of the present study, if representative of the whole genome, suggest that a whole-genome scan searching for common disease-susceptibility alleles would require markers spaced < or = 5 kb apart.

Familial cancer risks to offspring from mothers with 2 primary breast cancers: leads to cancer syndromes

The nationwide Swedish Family-Cancer Database was used to analyse the risk of cancer among the offspring of bilateral breast cancer patients. We studied 4,734 such mothers who had 9,391 offspring, of whom 328 presented with a primary cancer in the years 1958-1996. Standardised incidence ratios (SIRs) were increased for breast [SIR 3.05, 95% confidence interval (CI) 2.57-3.59], ovarian (SIR 1.84, 95% CI 1.03-3.05) and anogenital (SIR 1.75, 95% CI 1.11-2.63) cancers and childhood sarcomas (SIR 9.39, 95% CI 1.93-29.13). Additionally, squamous-cell skin cancer was increased among sons and all childhood cancers among daughters. When analysed by histological type, adenocarcinomas of the breast and ovary, all squamous-cell carcinomas and tumours at glandular epithelium (seminomas and intestinal carcinoids) were increased. Mothers with bilateral breast cancer had an excess of 2 or more children with cancer. The increased risk of ovarian cancer is consistent with germline mutations in the BRCA1 and BRCA2 genes, while the risk of soft tissue and bone sarcomas may reflect the association of these tumours with Li-Fraumeni syndrome. The increases in squamous-cell carcinomas at many sites may reflect a new susceptibility syndrome.