Table 1.

Summary characteristics of studies reporting associations of TL with prognostic factors (N = 33)

DesignCross-sectional studies: n = 16
Case–control studies: n = 2
Longitudinal cohort studies: n = 11
Randomized controlled trials: n = 4
ParticipantsNumber of participants: 30–657
Mean age: 44–75 years
Stage: 0–IV
TLDNA 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 factorsEthnicity: 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 factorsAge: 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.