Characteristics of studies investigating the association between global DNA methylation and breast cancer risk (n = 12)
| Prospective studies (n = 5) | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Study | Country | Study design | Study population | Sample size (cases/controls) | Age (years)a | Blood timing | Methylation assay | Methylation measure | Tissue |
| Brennan (2012; ref. 42) | United Kingdom | Nested case–control | BGS | 242/241 | 54/54 | N/R | Pyrosequencing | LINE1 | WBC |
| Italy | EPIC | 263/232 | 52/52 | ||||||
| Australia and New Zealand | KConFab | 218/153 | 50/60 | ||||||
| Deroo (2014; ref. 43) | USA and Puerto Rico | Case–cohort | Sister study | 294/646 | <60 | 1.3 years avg | Pyrosequencing | LINE1 | Whole blood |
| Severi (2014; ref. 44) | Australia | Nested case–control | MCCS | 420/420 | 64/64 | 50% > 8.9 years | Illumina 450k | Betas | Whole blood |
| van Veldhoven (2015; ref. 45) | Italy | Nested case–control | EPIC | 166/166 | 54.4/54.2 | 50% > 3.8 years | Illumina 450k | Betas | WBC |
| Norway | NOWAC | 192/192 | 55.4/55.4 | 50% > 2.1 years | Illumina 450k | ||||
| United Kingdom | BGS | 548/548 | 52.0/52.0 | N/R | WGBS | ||||
| Sturgeon (2017; ref. 46) | USA | Nested case–control | PLCO (control arm of intervention study) | 428/419 | 60+ | 68.6% > = 4 years | %5-mdC | Global | WBC |
| Nonprospective studies (n = 7) | |||||||||
| Study | Country | Study design | Study population | Sample size (cases/controls) | Age (years) a | Blood timing | Methylation assay | Methylation measure | Tissue |
| Choi (2009; ref. 47) | USA | Family-based case–control | American women | 176/173 | < 60 | At diagnosis | 5-mdC | Global | WBC |
| Cho (2010; ref. 48) | Turkey | Case–control | Turkish women | 40/40 | 50.8/48.3 | At diagnosis | MethylLight (%) | LINE1 | WBC |
| ALU | |||||||||
| SAT2 | |||||||||
| Wu (2012; ref. 49) | USA | Family-based case–control | Sisters discordant for breast cancer | 266/334 | 49.5/48.0 | At diagnosis | MethylLight (%) | LINE1 | WBC |
| ALU | |||||||||
| SAT2 | |||||||||
| Xu (2012; ref. 50) | USA | Population based case–control | American women (LIBCSP) | 1064/1101 | 60+ | At diagnosis | LUMA (% methylation) | LUMA | WBC |
| Pyrosequencing | LINE1 | ||||||||
| Kitkumthorn (2012; ref. 51) | Thailand | Population-based case–control | Women from Thailand | 36/144 | 50.28/47.72 | At diagnosis | COBRA (%) | LINE1 | WBC |
| Delgado-Cruzata (2012; ref. 52) | USA | Family-based case–control | Sisters discordant for breast cancer | 263/321 | 49.6/48.2 | At diagnosis | LUMA (% methylation) | LUMA | WBC |
| 3H-methyl | Global | ||||||||
| Kuchiba (2014; ref. 53) | Japan | Hospital-based case–control | Japanese women | 384/384 | 53.9/54.1 | At diagnosis | LUMA (% methylation) | LUMA | WBC |
↵aAverage age for cases/controls if available and age range if not available.