Fine-mapping of 150 breast cancer risk regions identifies 191 likely target genes

Genome-wide association studies have identified breast cancer risk variants in over 150 genomic regions, but the mechanisms underlying risk remain largely unknown. These regions were explored by combining association analysis with in silico genomic feature annotations. We defined 205 independent risk-associated signals with the set of credible causal variants in each one. In parallel, we used a Bayesian approach (PAINTOR) that combines genetic association, linkage disequilibrium and enriched genomic features to determine variants with high posterior probabilities of being causal. Potentially causal variants were significantly over-represented in active gene regulatory regions and transcription factor binding sites. We applied our INQUSIT pipeline for prioritizing genes as targets of those potentially causal variants, using gene expression (expression quantitative trait loci), chromatin interaction and functional annotations. Known cancer drivers, transcription factors and genes in the developmental, apoptosis, immune system and DNA integrity checkpoint gene ontology pathways were over-represented among the highest-confidence target genes.

Anthropometric and hormonal risk factors for male breast cancer: male breast cancer pooling project results

BACKGROUND

The etiology of male breast cancer is poorly understood, partly because of its relative rarity. Although genetic factors are involved, less is known regarding the role of anthropometric and hormonally related risk factors.

METHODS

In the Male Breast Cancer Pooling Project, a consortium of 11 case-control and 10 cohort investigations involving 2405 case patients (n = 1190 from case-control and n = 1215 from cohort studies) and 52013 control subjects, individual participant data were harmonized and pooled. Unconditional logistic regression generated study design-specific (case-control/cohort) odds ratios (ORs) and 95% confidence intervals (CIs), with exposure estimates combined using fixed effects meta-analysis. All statistical tests were two-sided.

RESULTS

Risk was statistically significantly associated with weight (highest/lowest tertile: OR = 1.36; 95% CI = 1.18 to 1.57), height (OR = 1.18; 95% CI = 1.01 to 1.38), and body mass index (BMI; OR = 1.30; 95% CI = 1.12 to 1.51), with evidence that recent rather than distant BMI was the strongest predictor. Klinefelter syndrome (OR = 24.7; 95% CI = 8.94 to 68.4) and gynecomastia (OR = 9.78; 95% CI = 7.52 to 12.7) were also statistically significantly associated with risk, relations that were independent of BMI. Diabetes also emerged as an independent risk factor (OR = 1.19; 95% CI = 1.04 to 1.37). There were also suggestive relations with cryptorchidism (OR = 2.18; 95% CI = 0.96 to 4.94) and orchitis (OR = 1.43; 95% CI = 1.02 to 1.99). Although age at onset of puberty and histories of infertility were unrelated to risk, never having had children was statistically significantly related (OR = 1.29; 95% CI = 1.01 to 1.66). Among individuals diagnosed at older ages, a history of fractures was statistically significantly related (OR = 1.41; 95% CI = 1.07 to 1.86).

CONCLUSIONS

Consistent findings across case-control and cohort investigations, complemented by pooled analyses, indicated important roles for anthropometric and hormonal risk factors in the etiology of male breast cancer. Further investigation should focus on potential roles of endogenous hormones.

Genetically Predicted Body Mass Index and Breast Cancer Risk: Mendelian Randomization Analyses of Data from 145,000 Women of European Descent

BACKGROUND

Observational epidemiological studies have shown that high body mass index (BMI) is associated with a reduced risk of breast cancer in premenopausal women but an increased risk in postmenopausal women. It is unclear whether this association is mediated through shared genetic or environmental factors.

METHODS

We applied Mendelian randomization to evaluate the association between BMI and risk of breast cancer occurrence using data from two large breast cancer consortia. We created a weighted BMI genetic score comprising 84 BMI-associated genetic variants to predicted BMI. We evaluated genetically predicted BMI in association with breast cancer risk using individual-level data from the Breast Cancer Association Consortium (BCAC) (cases  =  46,325, controls  =  42,482). We further evaluated the association between genetically predicted BMI and breast cancer risk using summary statistics from 16,003 cases and 41,335 controls from the Discovery, Biology, and Risk of Inherited Variants in Breast Cancer (DRIVE) Project. Because most studies measured BMI after cancer diagnosis, we could not conduct a parallel analysis to adequately evaluate the association of measured BMI with breast cancer risk prospectively.

RESULTS

In the BCAC data, genetically predicted BMI was found to be inversely associated with breast cancer risk (odds ratio [OR]  =  0.65 per 5 kg/m2 increase, 95% confidence interval [CI]: 0.56-0.75, p = 3.32 × 10-10). The associations were similar for both premenopausal (OR   =   0.44, 95% CI:0.31-0.62, p  =  9.91 × 10-8) and postmenopausal breast cancer (OR  =  0.57, 95% CI: 0.46-0.71, p  =  1.88 × 10-8). This association was replicated in the data from the DRIVE consortium (OR  =  0.72, 95% CI: 0.60-0.84, p   =   1.64 × 10-7). Single marker analyses identified 17 of the 84 BMI-associated single nucleotide polymorphisms (SNPs) in association with breast cancer risk at p < 0.05; for 16 of them, the allele associated with elevated BMI was associated with reduced breast cancer risk.

CONCLUSIONS

BMI predicted by genome-wide association studies (GWAS)-identified variants is inversely associated with the risk of both pre- and postmenopausal breast cancer. The reduced risk of postmenopausal breast cancer associated with genetically predicted BMI observed in this study differs from the positive association reported from studies using measured adult BMI. Understanding the reasons for this discrepancy may reveal insights into the complex relationship of genetic determinants of body weight in the etiology of breast cancer.

Allergic conditions and brain tumor risk

An inverse association between allergic conditions and glioma risk has been reported previously. In this large population-based case-control study, the authors identified cases diagnosed with glioma or meningioma in Denmark, Norway, Finland, Sweden, and southeast England between 2000 and 2004. Detailed information on self-reported physician-diagnosed allergic conditions was collected from 1,527 glioma cases, 1,210 meningioma cases, and 3,309 randomly selected controls. Logistic regression showed an odds ratio of 0.70 (95% confidence interval: 0.61, 0.80) for glioma associated with a diagnosis of any of asthma, hay fever, eczema, or other type of allergy. The risk estimates for glioma were around 0.65 for each allergic condition (asthma, eczema, hay fever, and food allergy), and the 95% confidence intervals were equally consistent, at around 0.55, 0.80. The reduced risks of glioma related to eczema, hay fever, and allergy overall, but not asthma, were confined to current rather than past conditions. Meningioma risk was not associated with allergic conditions, except for eczema (odds ratio = 0.74, 95% confidence interval: 0.60, 0.91). Our results show a reduced risk for glioma associated primarily with current allergic conditions. If this is etiologic, it has implications for the understanding of how allergic conditions might reduce the tumor risk.

Naevi and pigmentary characteristics as risk factors for melanoma in a high-risk population: a case-control study in New South Wales, Australia

The relationship between risk of cutaneous malignant melanoma and total body and site-specific naevus counts and other host factors was investigated in a Caucasian population aged 15-84 years in New South Wales, Australia. The study sample comprised 244 cases with melanoma diagnosed in 1989-1993, and 276 controls. The strongest relationship was with total body naevus count. Risk of melanoma was raised 12 times in those with more than 100 naevi compared with those with less than 10. There were also strong risks, with odds ratios of 5 or more, associated with having multiple atypical naevi, multiple large naevi, high naevus counts in sun-exposed or sun-protected areas and being unable to tan on repeated sun exposure. The effect of inability to tan was stronger at younger than older ages. Lesser risks, with odds ratios of 2-3, were associated with being prone to burn on sun exposure, having many freckles as a child and having red hair. The site distribution of naevi in males compared with females resembled the distribution of melanoma by sex. Risk of melanoma of the back was significantly more closely related to back naevus count than naevus count for the remainder of the body. For other anatomical sites, naevus count was non-significantly more closely related to naevus counts at that site than counts over the remainder of the body. Naevus count declined with age in both cases and controls. In those aged under 40, having 100 or more naevi was associated with an aetiological fraction (AF) of 41%. In those aged 60 and over, however, the AF associated with this number of naevi was only 5%.

Do tanning lamps cause melanoma? An epidemiologic assessment

Sun exposure is a known cause of melanoma, and there are several reasons for concern that tanning lamp use may also cause melanoma, especially because of the spectral output of the lamps,the similarity of tanning lamp use to natural sun exposure (particularly sunbathing), the reported association of melanoma with PUVA therapy, and the positive results in several case-control studies of melanoma risk and tanning lamp use. We have reviewed the epidemiologic literature relevant to the relation between tanning lamp use and melanoma and have discussed methodologic issues that should be considered in interpreting these reports and designing improved studies. Although several investigations have found a positive relation between tanning lamp use and melanoma, in some instances including dose-response or duration-response effects, the methodologic limitations preclude any firm conclusion regarding a causative relation. Meta-analysis of existing data may provide better information, but several limitations could only be overcome by new studies collecting more precise exposure data. The popularity of tanning lamp use, especially in young persons, adds urgency to the quest for elucidation of the relation between the use of these devices and melanoma risk.

Mortality from cerebrovascular disease in a cohort of 23 000 patients with insulin-treated diabetes

BACKGROUND AND PURPOSE

Disease of the cardiovascular system is the main cause of long-term complications and mortality in patients with type I (insulin-dependent) and type II (non-insulin-dependent) diabetes. Cerebrovascular mortality rates have been shown to be raised in patients with type II diabetes but have not previously been reported by age and sex in patients with type I diabetes.

METHODS

A cohort of 23 751 patients with insulin-treated diabetes, diagnosed under the age of 30 years from throughout the United Kingdom, was identified during 1972 to 1993 and followed up for mortality until the end of December 2000. Age- and sex-specific mortality rates and standardized mortality ratios (SMRs) were calculated.

RESULTS

There were 1437 deaths during the follow-up, 80 due to cerebrovascular disease. Overall, the cerebrovascular mortality rates in the cohort were higher than the corresponding rates in the general population, and the SMRs were 3.1 (95% CI, 2.2 to 4.3) for men and 4.4 (95% CI, 3.1 to 6.0) for women. When stratified by age, the SMRs were highest in the 20- to 39-year age group. After subdivision of cause of death into hemorrhagic and nonhemorrhagic origins, there remained a significant increase in mortality from stroke of nonhemorrhagic origin.

CONCLUSIONS

Analyses of mortality from this cohort, essentially one of patients with type I diabetes, has shown for the first time that cerebrovascular mortality is raised at all ages in these patients. Type I diabetes is at least as great a risk factor for cerebrovascular mortality as type II diabetes.

Cancer incidence following treatment for infertility at a clinic in the UK

BACKGROUND

There is concern about the long-term health impact of ovarian stimulation treatment for infertility, in particular the effect on cancer risk. The aim of this study was to investigate the incidence of cancer in a cohort of women attending a large infertility clinic in the UK.

METHODS

Women who were UK residents attending the clinic between January 1, 1975 and December 31, 1989 were identified for the study. The cohort was followed-up and cancer incidence rates calculated.

RESULTS

The study cohort was made up of 5556 women of whom 75% had received ovarian stimulation drug treatment at the clinic. A total of 118 cancers (including 55 breast, four corpus uteri and six ovarian) were incident in the cohort from the beginning of 1990 to the end of 1997. The incidence rates of cancer of the breast, corpus uteri and ovary were not significantly different from expectation based on national cancer rates, and were similar for women who had received hormonal treatment to stimulate their ovaries and those who had not.

CONCLUSIONS

These data do not support a hypothesis linking infertility treatment involving ovarian stimulation with increased breast, uterine and ovarian cancer over the follow-up period studied.

Mortality of doctors in different specialties: findings from a cohort of 20000 NHS hospital consultants

OBJECTIVES

To examine patterns of cause specific mortality in NHS hospital consultants according to their specialty and to assess these in the context of potential occupational exposures.

METHODS

A historical cohort assembled from Department of Health records with follow up through the NHS Central Register involving 18,358 male and 2168 female NHS hospital consultants employed in England and Wales between 1962 and 1979. Main outcome measures examined were cause specific mortality during 1962-92 in all consultants combined, and separately for 17 specialty groups, with age, sex, and calendar year adjusted standardised mortality ratios (SMRs) for comparison with national rates, and rate ratios (RRs) for comparison with rates in all consultants combined.

RESULTS

The 2798 deaths at ages 25 to 74 reported during the 30 year study period were less than half the number expected on the basis of national rates (SMR 48, 95% confidence interval (95% CI) 46 to 49). Low mortality was evident for cardiovascular disease, lung cancer, other diseases related to smoking, and particularly for diabetes (SMR 14, 95% CI 6 to 29). Death rates from accidental poisoning were significantly raised among male consultants (SMR 227, 95% CI 135 to 359), the excess being most apparent in obstetricians and gynaecologists (SMR 934); almost all deaths from accidental poisoning involved prescription drugs. A significantly raised death rate from injury and poisoning among female consultants was due largely to a twofold excess of suicide (SMR 215, 95% CI 93 to 423), the rate for this cause being significantly raised in anaesthetists (SMR 405). Compared with all consultants, significantly raised mortality was found in psychiatrists for all causes combined (RR 1.12), ischaemic heart disease (RR 1.18), and injury and poisoning (RR 1.46); in anaesthetists for cirrhosis (RR 2.22); and in radiologists and radiotherapists for respiratory disease (RR 1.68). There were significant excesses of colon cancer in psychiatrists (RR 1.67, compared with all consultants) and ear, nose, and throat surgeons (RR 2.25); melanoma in anaesthetists (RR 3.33); bladder cancer in general surgeons (RR 2.40); and laryngeal cancer in ophthalmologists (RR 7.63).

CONCLUSIONS

Lower rates of smoking will have contributed substantially to the low overall death rates found in consultants, but other beneficial health related behaviours, and better access to health care, may have also played a part. The increased risks of accidental poisoning in male consultants, and of suicide in female consultants are of concern, and better preventive measures are needed. The few significant excesses of specific cancers found in certain specialties have no obvious explanation other than chance. A significant excess mortality from cirrhosis in anaesthetists might reflect an occupational hazard and may warrant further investigation.

Determinants of age at menarche in the UK: analyses from the Breakthrough Generations Study

BACKGROUND

Early menarche increases breast cancer risk but, aside from weight, information on its determinants is limited.

METHODS

Age at menarche data were collected retrospectively by questionnaire from 81,606 women aged 16-98, resident in the UK and participating in the Breakthrough Generations Study.

RESULTS

Menarche occurred earlier in women who had a low birthweight (P(trend)<0.001), were singletons (P<0.001), had prenatal exposure to pre-eclampsia (P<0.001) or maternal smoking (P=0.01), were not breastfed (P(trend)=0.03), were non-white (P<0.001), were heavy (P(trend)<0.001) or tall (P(trend)<0.001) compared with their peers at age 7 and exercised little as a child (P(trend)<0.001). Menarcheal age increased with number of siblings (P<0.001) independently of birth order, and had an inverse association with birth order after adjustment for sibship size (P<0.001). In a multivariate model, birthweight, ethnicity, weight, height, exercise, sibship size and birth order remained significant, and maternal age at birth became significant (positive association, P<0.001).

CONCLUSION

Age at menarche was influenced by both pre- and post-natal factors, and these factors may affect breast cancer risk through this route.

Testicular cancer and antecedent diseases

A case-control study of the aetiology of testicular cancer was conducted using information obtained by interview and from case-notes of 259 cases with testicular cancer and two sets of control patients -238 men with diagnoses other than testicular cancer attending the same radiotherapy centres as those attended by the cases, and 251 hospital in-patients not attending radiotherapy departments. Logistic regression analyses were performed, after stratifying by age and region of residence, to estimate the relative risks (RRs) associated with various aspects of prior medical history. The risk of testicular cancer was found to be raised for men with a history of cryptorchidism (RR based on comparison with all controls = 6.3; P less than 0.001), inguinal hernia (RR = 1.6; P = 0.14), mumps orchitis (RR = 12.7; P = 0.006), atopy (RR = 1.8; P = 0.03), and meningitis (RR = 3.0; P = 0.21). Inguinal herniorrhaphy before the age of 15 years was particularly a risk factor for seminoma, whereas the relative risks were similar for seminoma and teratoma for the other factors. The results add to the growing evidence that congenital abnormalities involving the process of testicular descent and closure of the processus vaginalis are risk factors for testicular cancer, and that some types of testicular damage later in life may also be important. The findings of associations with previous atopy and certain infections suggest a possible second aetiological mechanism - that immunological abnormalities may be associated with an increased risk of testis cancer.

Incidence of malignant melanoma of the skin in England and Wales and its relationship to sunshine

In most of England and Wales the incidence of malignant melanoma of the skin has risen rapidly in recent years, especially in women. Mean incidences in the 14 English health regions and Wales correlated negatively with latitude and positively with hours of sunshine, suggesting that exposure to sunshine was an important causal factor. Male and female incidences within a region tended to show similar yearly fluctuations, implying a common factor affecting the incidence in both men and women with a short latent period of action. This factor may be exposure to sunshine, which may cause melanoma after an induction period of about two years; for women the incidence of melanoma in the regions of England and Wales correlated positively with hours of sunshine two years earlier.

Birthweight, childhood growth and risk of breast cancer in a British cohort

We have examined the relationship between birthweight and risk of breast cancer, taking into account growth in childhood, using data on a total of 2221 women born in 1946 and followed up to 1997. Thirty-seven breast cancers occurred during follow-up. There was evidence of greater risk of breast cancer with greater birthweight (rate ratio = 1.76 (95% CI: 0.92, 3.35) for birthweight >/= 3.5 kg vs birthweight < 3.5 kg), which was more marked at pre-menopausal ages (RR = 2.31, 95% CI: 0.93, 5.74). The relation with birthweight was not substantially confounded by any of the measured adult risk factors. A significant interaction was observed between the effects of birthweight and height at age 7 years. Relative to those born lighter than 3.5 kg, women who were heavy at birth (>/= 3.5 kg) and short or average at 7 years (< 1.22 m) had a 21% increase in breast cancer rates (RR = 1.21; 95% CI = 0.49-2.99), while women who were heavy at birth (>/= 3.5 kg) but tall at 7 years (>/= 1.22 m) had a four-fold increase (RR = 4.01; 95% CI = 1.82-8.83). These results suggest that the effect of birthweight on breast cancer risk may be modulated by childhood growth.

A genome-wide association study of early menopause and the combined impact of identified variants

Early menopause (EM) affects up to 10% of the female population, reducing reproductive lifespan considerably. Currently, it constitutes the leading cause of infertility in the western world, affecting mainly those women who postpone their first pregnancy beyond the age of 30 years. The genetic aetiology of EM is largely unknown in the majority of cases. We have undertaken a meta-analysis of genome-wide association studies (GWASs) in 3493 EM cases and 13 598 controls from 10 independent studies. No novel genetic variants were discovered, but the 17 variants previously associated with normal age at natural menopause as a quantitative trait (QT) were also associated with EM and primary ovarian insufficiency (POI). Thus, EM has a genetic aetiology which overlaps variation in normal age at menopause and is at least partly explained by the additive effects of the same polygenic variants. The combined effect of the common variants captured by the single nucleotide polymorphism arrays was estimated to account for ∼30% of the variance in EM. The association between the combined 17 variants and the risk of EM was greater than the best validated non-genetic risk factor, smoking.

Height and Breast Cancer Risk: Evidence From Prospective Studies and Mendelian Randomization

BACKGROUND

Epidemiological studies have linked adult height with breast cancer risk in women. However, the magnitude of the association, particularly by subtypes of breast cancer, has not been established. Furthermore, the mechanisms of the association remain unclear.

METHODS

We performed a meta-analysis to investigate associations between height and breast cancer risk using data from 159 prospective cohorts totaling 5216302 women, including 113178 events. In a consortium with individual-level data from 46325 case patients and 42482 control patients, we conducted a Mendelian randomization analysis using a genetic score that comprised 168 height-associated variants as an instrument. This association was further evaluated in a second consortium using summary statistics data from 16003 case patients and 41335 control patients.

RESULTS

The pooled relative risk of breast cancer was 1.17 (95% confidence interval [CI] = 1.15 to 1.19) per 10cm increase in height in the meta-analysis of prospective studies. In Mendelian randomization analysis, the odds ratio of breast cancer per 10cm increase in genetically predicted height was 1.22 (95% CI = 1.13 to 1.32) in the first consortium and 1.21 (95% CI = 1.05 to 1.39) in the second consortium. The association was found in both premenopausal and postmenopausal women but restricted to hormone receptor-positive breast cancer. Analyses of height-associated variants identified eight new loci associated with breast cancer risk after adjusting for multiple comparisons, including three loci at 1q21.2, DNAJC27, and CCDC91 at genome-wide significance level P < 5×10(-8).

CONCLUSIONS

Our study provides strong evidence that adult height is a risk factor for breast cancer in women and certain genetic factors and biological pathways affecting adult height have an important role in the etiology of breast cancer.

Prenatal and familial associations of testicular cancer

In a case-control study of testis cancer 259 cases with testicular cancer, 238 controls treated at radiotherapy centres and 251 non-radiotherapy hospital in-patient controls were interviewed about some possible prenatal and familial risk factors for the tumour. For firstborn men, the risk of testis cancer increased significantly according to maternal age at the subject's birth, and this effect was most marked for seminoma. The association with maternal age was not apparent for cases other than firstborn. The risk of testis cancer was also significantly raised for men from small sibships and of early birth order. These results accord with the theory that raised maternal levels of available oestrogen during the early part of pregnancy are aetiological for testicular cancer in the son, although other explanations are possible; there is evidence that seminoma risk may particularly be affected.

Cancer mortality in relatives of women with breast cancer: the OPCS Study. Office of Population Censuses and Surveys

Mortality from cancer and other causes in male and female first-degree relatives of women with breast cancer diagnosed before age 60 has been examined in a large population-based cohort study, providing estimates of familial risks free from ascertainment or recall bias. Relatives of 3,295 patients with breast cancer diagnosed in the UK between 1954 and 1981 were identified through a register of households established in 1939. The 11,678 first-degree relatives thus identified were followed up through national records until the end of 1992. Over this period 5,421 deaths (including 1,527 cancer deaths) occurred in these relatives. Mortality from breast cancer was significantly raised in first-degree relatives (SMR 187, 248 deaths), and there was also significant excess mortality from cancers of the larynx (SMR 177, 17 deaths), endometrium (SMR 166, 29 deaths) and unspecified neoplasms (SMR 153, 70 deaths). The SMR for ovarian cancer was 130, based on 58 deaths (p = 0.06). There was no marked excess for other sites or for non-neoplastic causes of death, but there was a significant deficit in mortality from cervical cancer (SMR 63, 18 deaths). The SMR for breast cancer increased significantly with decreasing age of the relative. After allowing for age, sisters of cases had a slightly (though non-significantly) higher risk than mothers (ratio of SMRs 1.22). These results, together with penetrance estimates from linked families, suggest that approximately one woman in 800 carries BRCAI, the susceptibility gene on chromosome 17q, and that this gene causes about 1% of all breast cancers.

19p13.1 is a triple-negative-specific breast cancer susceptibility locus

The 19p13.1 breast cancer susceptibility locus is a modifier of breast cancer risk in BRCA1 mutation carriers and is also associated with the risk of ovarian cancer. Here, we investigated 19p13.1 variation and risk of breast cancer subtypes, defined by estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor-2 (HER2) status, using 48,869 breast cancer cases and 49,787 controls from the Breast Cancer Association Consortium (BCAC). Variants from 19p13.1 were not associated with breast cancer overall or with ER-positive breast cancer but were significantly associated with ER-negative breast cancer risk [rs8170 OR, 1.10; 95% confidence interval (CI), 1.05-1.15; P = 3.49 × 10(-5)] and triple-negative (ER-, PR-, and HER2-negative) breast cancer (rs8170: OR, 1.22; 95% CI, 1.13-1.31; P = 2.22 × 10(-7)). However, rs8170 was no longer associated with ER-negative breast cancer risk when triple-negative cases were excluded (OR, 0.98; 95% CI, 0.89-1.07; P = 0.62). In addition, a combined analysis of triple-negative cases from BCAC and the Triple Negative Breast Cancer Consortium (TNBCC; N = 3,566) identified a genome-wide significant association between rs8170 and triple-negative breast cancer risk (OR, 1.25; 95% CI, 1.18-1.33; P = 3.31 × 10(-13)]. Thus, 19p13.1 is the first triple-negative-specific breast cancer risk locus and the first locus specific to a histologic subtype defined by ER, PR, and HER2 to be identified. These findings provide convincing evidence that genetic susceptibility to breast cancer varies by tumor subtype and that triple-negative tumors and other subtypes likely arise through distinct etiologic pathways.

Genome-wide association and transcriptome studies identify target genes and risk loci for breast cancer

Genome-wide association studies (GWAS) have identified more than 170 breast cancer susceptibility loci. Here we hypothesize that some risk-associated variants might act in non-breast tissues, specifically adipose tissue and immune cells from blood and spleen. Using expression quantitative trait loci (eQTL) reported in these tissues, we identify 26 previously unreported, likely target genes of overall breast cancer risk variants, and 17 for estrogen receptor (ER)-negative breast cancer, several with a known immune function. We determine the directional effect of gene expression on disease risk measured based on single and multiple eQTL. In addition, using a gene-based test of association that considers eQTL from multiple tissues, we identify seven (and four) regions with variants associated with overall (and ER-negative) breast cancer risk, which were not reported in previous GWAS. Further investigation of the function of the implicated genes in breast and immune cells may provide insights into the etiology of breast cancer.

Genome-wide association study identifies a common variant in RAD51B associated with male breast cancer risk

We conducted a genome-wide association study of male breast cancer comprising 823 cases and 2,795 controls of European ancestry, with validation in independent sample sets totaling 438 cases and 474 controls. A SNP in RAD51B at 14q24.1 was significantly associated with male breast cancer risk (P = 3.02 × 10(-13); odds ratio (OR) = 1.57). We also refine association at 16q12.1 to a SNP within TOX3 (P = 3.87 × 10(-15); OR = 1.50).

History of allergies and risk of glioma in adults

Epidemiological studies have consistently reported an inverse association between a history of allergic disease and risk of glioma. The reason for this association is unclear, and there is a lack of studies with the detail and size to explore the association in depth. We conducted a UK population-based case-control study with 965 glioma cases and 1,716 controls to investigate glioma risk in relation to allergic disease. Risk was reduced in subjects reporting a history of asthma (odds ratio (OR) = 0.71, 95% confidence interval (CI): 0.54-0.92), hay fever (OR = 0.73, 95% CI: 0.59-0.90), eczema (OR = 0.74, 95% CI: 0.56-0.97) and other allergies (OR = 0.65, 95% CI: 0.47-0.90). Risk was reduced for all the main histological groups. There was no significant trend of risk with age, at the onset of each condition, or the number of conditions reported. Risk reductions were strongest for asthma or hay fever with recent onset. Risk in asthmatic subjects was not related to frequency of use of antiasthmatic drugs, but was significantly reduced for use of antiallergenic medication among subjects with hay fever. The study showed an inverse association of glioma risk with allergic disease. Possible reasons for the association, as well as potential immunological aetiology, include confounding, bias and reverse causality.

Bias in the standardized mortality ratio when using general population rates to estimate expected number of deaths

Cohort studies often compare the observed number of cases arising in a group under investigation with the number expected to occur on the basis of general population rates. The general population is taken to represent unexposed persons, but it is almost inevitably biased in that it comprises all types of people including exposed ones. To identify circumstances when this bias matters, the authors modeled its effect in relation to the size of the observed standardized mortality ratio (SMR) and the prevalence of exposed individuals in the general population. The authors found that bias may be a major problem, causing substantial underestimation of the true relative risk, when either the prevalence of exposure in the general population or the SMR are large. The bias can cause an apparent trend in SMRs with age when none exists. It also places a limit on the maximum size of the observed SMR, no matter how large the true relative risk. A table is provided showing the extent of bias in different circumstances. Cohort studies of people with common diseases or exposures, or that find large SMRs, when using general population expectations, need to consider the extent of bias from this source.

Melanocytic naevi and melanoma: an epidemiological perspective

There is growing evidence that individuals at high risk of cutaneous melanoma can be identified by the use of simple measures of benign melanocytic naevi--raised risk occurring in persons who have large numbers of naevi, or naevi with atypical clinical features. Very high risk of melanoma appears to exist in two rare groups: persons with dysplastic naevi whose families include at least two individuals who have had melanoma, and persons with giant congenital naevi. Risks of melanoma in other individuals with dysplastic naevi and in persons with small congenital naevi have not yet been quantified. Much of the published work on risk of melanoma in relation to naevi has been based on clinical series or assemblage of case reports, with great potential for bias. In such studies, naevi have often been classified into dichotomies or syndromes originally defined for pathological or clinical purposes, frequently using poorly reproducible criteria. Case-control and cohort studies of the relationship of naevi to melanoma are needed, which use reproducible criteria and designs minimizing bias, and which examine risk in relation to graded clinical and histological measures of naevi.

Sexual history and Epstein-Barr virus infection

To determine the role of sexual contact in transmission of Epstein-Barr virus (EBV) and occurrence of infectious mononucleosis (IM), a cross-sectional study was undertaken of EBV serologic testing and histories of IM and sexual behavior among 1006 new students at Edinburgh University. Prevalence of EBV seropositivity was significantly greater among women (79.2%) than among men (67.4%; P<.001) and among those who had ever been sexually active (82.7%) than among those who had not (63.7%; P<.001). Having a greater number of sex partners was a highly significant risk factor for EBV seropositivity. Two thirds of IM cases, but only a tenth of asymptomatic primary EBV infections, were statistically attributable to sexual intercourse. The findings suggest that EBV transmission occurs during sexual intercourse or closely associated behaviors. Transmission in this way appears to account for most cases of IM but for only a minority of cases of asymptomatic EBV infection, which mainly occur at younger ages.