Publications by authors named "Melissa C Southey"

Obesity has been associated with non-Hodgkin lymphoma (NHL), but the evidence is inconclusive. We examined the association between genetically determined adiposity and four common NHL subtypes: diffuse large B-cell lymphoma (DLBCL), follicular lymphoma, chronic lymphocytic leukemia, and marginal zone lymphoma, using eight genome-wide association studies of European ancestry (N = 10,629 cases, 9505 controls) and constructing polygenic scores for body mass index (BMI), waist-to-hip ratio (WHR), and waist-to-hip ratio adjusted for BMI (WHRadjBMI). Higher genetically determined BMI was associated with an increased risk of DLBCL [odds ratio (OR) per standard deviation (SD) = 1.

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Objective: The performance of FFPE tissue-derived DNA on the MethylationEpicV1.0 array can be unpredictable as the protocol only has two quality checks; checkpoint 1 for DNA quantity and checkpoint 2 for DNA quality assessment. We sought to incorporate a third, previously developed bisulfite conversion quality check prior to processing 255 FFPE tissue derived DNA samples.

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Background: Endometrial cancer is the most common gynaecological cancer in high-income countries. In addition to environmental risk factors, genetic predisposition contributes towards endometrial cancer development but is still incompletely defined.

Methods: Building on genome-wide association studies (GWASs) by the Endometrial Cancer Association Consortium, we conducted a GWAS meta-analysis of 17,278 endometrial cancer cases and 289,180 controls, incorporating biobank samples from the UK, Finland, Estonia and Japan.

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Importance: Etiologic heterogeneity in breast carcinogenesis needs to be well characterized for targeted prevention. Associations between menopausal hormonal therapy (MHT) and oral contraceptive (OC) use and breast cancer intrinsic-like subtypes are not well understood.

Objective: To examine whether exogenous hormone use is differentially associated with breast cancer subtypes and to evaluate heterogeneity by intrinsic-like subtypes.

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DNA methylation in breast tumours has been extensively studied and has provided valuable insights into the clinical heterogeneity of breast cancer. In this review, we summarise the current literature that has used DNA methylation markers to subtype breast cancer and predict progression and survival. Widespread methylation differences have been observed across breast cancer subtypes at both the candidate genes and in genome-wide analyses, most notably between oestrogen receptor (ER) positive and ER-negative subtypes and for triple-negative tumours.

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Clinical genetic testing identifies variants causal for hereditary cancer, information that is used for risk assessment and clinical management. Unfortunately, some variants identified are of uncertain clinical significance (VUS), complicating patient management. Case-control data is one evidence type used to classify VUS.

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Targeted gene panel sequencing that measures genomic variation at different depths has potential diagnostic application. A targeted gene panel, smart nonuniformity sequencing, was developed to detect somatic variants associated with clonal hematopoiesis of indeterminate potential (CHIP), which requires an optimal sequencing depth of >500×; and germline variants requiring a lower ≥50× depth (panel 1). This was achieved by adjusting probe ratios for genomic regions relevant to identifying CHIP in comparison to those relevant to germline variation analysis.

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Background: Type 2 diabetes (T2D) is characterized by elevated levels of metabolic and inflammatory markers but less is known about other molecular alterations that occur with aging. We aimed to assess the associations of DNA methylation-based measures of aging (epigenetic aging) with prevalent and incident T2D in a large sample of middle-aged and older Australians.

Methods: We used data from 5 403 participants in the Melbourne Collaborative Cohort Study (mean age = 59 years).

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Background: The adverse gut microbiome may underlie the variability in risks of colorectal cancer (CRC) and metachronous CRC in people with Lynch syndrome (LS). The role of pksEscherichia coli (pksE. coli), Enterotoxigenic Bacteroides fragilis (ETBF), and Fusobacterium nucleatum (Fn) in CRCs and adenomas in people with LS is unknown.

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Background: Breast cancer is multifactorial. Focusing on limited risk factors may miss high-risk individuals.

Methods: We assessed the performance and overlap of various risk factors in identifying high-risk individuals for invasive breast cancer (BrCa) and ductal carcinoma in situ (DCIS) in 161,849 European-ancestry and 18,549 Asian-ancestry women.

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Background: The ataxia-telangiectasia mutated (ATM) kinase phosphorylates and activates several downstream targets that are essential for DNA damage repair, cell cycle inhibition and apoptosis. Germline biallelic inactivation of the ATM gene causes ataxia-telangiectasia (A-T), and heterozygous pathogenic variant (PV) carriers are at increased risk of cancer, notably breast cancer. This study aimed to investigate whether DNA methylation profiling can be useful as a biomarker to identify tumors arising in ATM PV carriers, which may help for the management and optimal tailoring of therapies of these patients.

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Objective: Screening high-risk individuals with low-dose CT reduces mortality from lung cancer, but many lung cancers occur in individuals who are not eligible for screening. Risk biomarkers may be useful to refine risk models and improve screening eligibility criteria. We evaluated if blood-based DNA methylation markers can improve a traditional lung cancer prediction model.

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Background: Tumour DNA methylation has been investigated as a potential marker for breast cancer survival, but findings often lack replication across studies.

Methods: This study sought to replicate previously reported associations for individual CpG sites and multi-CpG signatures using an Australian sample of 425 women with breast cancer from the Melbourne Collaborative Cohort Study (MCCS). Candidate methylation sites (N = 22) and signatures (N = 3) potentially associated with breast cancer survival were identified from five prior studies that used The Cancer Genome Atlas (TCGA) methylation dataset, which shares key characteristics with the MCCS: comparable sample size, tissue type (formalin-fixed paraffin-embedded; FFPE), technology (Illumina HumanMethylation450 array), and participant characteristics (age, ancestry, and disease subtype and severity).

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Background: The 313-variant polygenic risk score (PRS) provides a promising tool for clinical breast cancer risk prediction. However, evaluation of the PRS across different European populations which could influence risk estimation has not been performed.

Methods: We explored the distribution of PRS across European populations using genotype data from 94,072 females without breast cancer diagnosis, of European-ancestry from 21 countries participating in the Breast Cancer Association Consortium (BCAC) and 223,316 females without breast cancer diagnosis from the UK Biobank.

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Aims: Clustering algorithms have been widely applied to tumor DNA methylation datasets to define methylation-based cancer subtypes. This study aimed to evaluate the agreement between subtypes obtained from common clustering strategies.

Materials & Methods: We used tumor DNA methylation data from 409 women with breast cancer from the Melbourne Collaborative Cohort Study (MCCS) and 781 breast tumors from The Cancer Genome Atlas (TCGA).

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Menopausal users of hormone replacement therapy (HRT) are at increased breast cancer risk and decreased colorectal cancer (CRC) risk compared with individuals who have never used HRT, but these opposing associations may differ by familial risk of breast cancer and CRC. We harmonized data from 3 cohorts and generated separate breast cancer and CRC familial risk scores based on cancer family history. We defined moderate or strong family history as a risk score of 0.

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Article Synopsis
  • - DNA methylation is an important epigenetic mechanism that regulates gene expression, and DNMT inhibitors are used extensively in research to study this process.
  • - Researchers developed a CRISPR-based method called SAM-DNMT3A that unexpectedly induces global DNA methylation, regardless of the specific DNA target.
  • - This approach reveals a potential therapeutic vulnerability in ER-positive breast cancer and emphasizes the need for careful use of CRISPR technology in methylation studies.
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  • The study investigates the impact of wildfire-related particulate matter (PM) on epigenetic aging, revealing a link between exposure levels and increased biological aging.
  • For every 1 µg/m increase in annual wildfire PM, there was an acceleration of 0.25 years in GrimAge1 and 0.36 years in GrimAge2, indicating faster aging impacts.
  • Older adults, individuals with smoking or alcohol backgrounds, and those in rural areas are particularly affected, highlighting the health risks associated with wildfire smoke exposure.
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As the possibility of implementing population genomic screening programs for the risk of developing hereditary cancers in health systems increases, understanding how to support individuals who wish to have genomic screening is essential. This qualitative study aimed to link public perceived barriers to a) taking up the offer of population genomic screening for breast or prostate cancer risk and b) taking up risk-management options following their result, with possible theory-informed behaviour-change approaches that may support implementation. Ten focus groups were conducted with a total of 25 members of the Australian public to identify and then categorise barriers within the behaviour-change Capability, Opportunity, Motivation - Behaviour (COM-B) model.

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Background: Age is one of the strongest risk factors for breast cancer. Measures of biological age based on DNA methylation have gained popularity for their strong association with risk of many diseases, including cancer, which may help to identify high-risk subgroups for targeted prevention.

Methods: We carried out a systematic review of prospective studies that examined the association of methylation-based markers of ageing with risk of invasive breast cancer in healthy (breast cancer-free) women, published up to May 2023.

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Epigenetic age quantifies biological age using DNA methylation information and is a potential pathway by which physical activity benefits general health. We aimed to assess the cross-sectional and longitudinal associations between physical activity and epigenetic age in middle-aged and older Australians. Blood DNA methylation data for 6208 participants (40% female) in the Melbourne Collaborative Cohort Study (MCCS) were available at baseline (1990-1994, mean age, 59 years) and, of those, for 1009 at follow-up (2003-2007, mean age, 69 years).

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Article Synopsis
  • Known genetic risk factors account for about one-third of familial endometrial cancer cases, but the link between rare germline copy number variants (CNVs) and cancer risk is not well understood.
  • A study analyzed DNA from over 4,000 endometrial cancer patients and nearly 18,000 controls, finding that the cancer group had a significantly higher number of CNVs.
  • The research identified 141 gene loci potentially related to endometrial cancer risk, highlighting a specific area (16p11.2) with recurrent deletions that could help further investigations into genetic susceptibility.
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  • Further research on identified regions could enhance our understanding of genetic risks for glioma.
  • The study indicates that sex might influence genetic susceptibility to glioma.
  • It emphasizes the need for future glioma studies to consider sex-specific factors in their analyses.*
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Article Synopsis
  • The study investigates the relationship between hormonal contraceptive use and breast cancer risk in both unaffected women and mutation carriers.
  • Out of the participants, it was found that hormonal contraceptive use was linked to a higher breast cancer risk in mutation carriers, particularly with longer duration of use.
  • The findings suggest that decisions regarding hormonal contraceptive use for women with genetic mutations should consider individual risk factors and benefits.
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The role of nutrition in healthy ageing is acknowledged but details of optimal dietary composition are still uncertain. We aimed to investigate the cross-sectional associations between dietary exposures, including macronutrient composition, food groups, specific foods, and overall diet quality, with methylation-based markers of ageing. Blood DNA methylation data from 5310 participants (mean age 59 years) in the Melbourne Collaborative Cohort Study were used to calculate five methylation-based measures of ageing: PCGrimAge, PCPhenoAge, DunedinPACE, ZhangAge, TelomereAge.

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