Design | Cross-sectional studies: n = 16 |

Case–control studies: n = 2 | |

Longitudinal cohort studies: n = 11 | |

Randomized controlled trials: n = 4 | |

Participants | Number of participants: 30–657 |

Mean age: 44–75 years | |

Stage: 0–IV | |

TL | DNA source: |

Peripheral blood: n = 13 | |

Breast tumor tissue: n = 20 | |

DNA extraction method: | |

Columns: n = 8 | |

Phenol–chloroform: n = 2 | |

Salt extraction method: n = 2 | |

Magnetic glass particles: n = 1 | |

Not reported: n = 12 | |

Not applicable: n = 8 | |

Measurement method: | |

Southern blot: n = 9 | |

Slot blot: n = 4 | |

qPCR: n = 9 | |

FISH (qualitative/semi-quantitative): n = 4 | |

Q-FISH: n = 5 | |

STELA: n = 1 | |

Not reported: n = 1 | |

Potential prognostic factors | Ethnicity: n = 5 |

Physical activity: n = 3 | |

BMI/weight: n = 2 | |

Smoking/nicotine intake: n = 3 | |

Alcohol intake: n = 1 | |

Psychologic factors: n = 4 | |

Mood disturbances: n = 3 | |

Perceived stress: n = 2 | |

Sleep: n = 2 | |

Fatigue: n = 1 | |

Psychosocial intervention: n = 3 | |

Traditional prognostic factors | Age: n = 16 |

Tumor size: n = 10 | |

Tumor grade: n = 10 | |

Histologic type: n = 6 | |

Nodal involvement: n = 11 | |

Stage: n = 13 | |

Metastasis: n = 1 | |

Local recurrence: n = 1 | |

Molecular subtype: n = 16 | |

Chemotherapy: n = 6 | |

Hormonal therapy: n = 3 | |

Treatment received: n = 2 | |

Comorbid conditions: n = 1 |

Abbreviation:

*n*: number of studies.