Summary of study variables for included studies across Africa and by region
| Study variables | All studies (n=67) | North African studies (n=29) | East African studies (n=10) | Southern African studies (n=8) | Central African study (n=1) | West African studies (n=17) | West and East African studies (n=2) |
| Mean age (SD) | 49.21 (5.25) (n=42) | 48.47 (6.35) (n=17) | 48.65 (3.34) (n=7) | 56.09 (2.53) (n=5) | 50.00 (n/a) (n=1) | 47.67 (2.65) (n=12) | Not investigated |
| Median age (IQR) | 48.75 (4.50) (n=18) | 47.00 (5.72) (n=9) | 48.75 (0.87) (n=4) | 56.00 (3.00) (n=3) | 49.00 (n/a) (n=1) | Not investigated | 56.00 (n/a) (n=1) |
| Grade 1 tumours, median (IQR) | 9.56% (7.34) (n=52) | 8.44% (6.90) (n=23) | 10.66% (9.35) (n=8) | 11.40% (1.95) (n=6) | 1.15% (n/a) (n=1) | 6.06% (11.18) (n=13) | W: 9.56% (n/a), E: 15.25% (n/a) (n=1) |
| Grade 2 tumours, median (IQR) | 51.11% (16.97) (n=53) | 57.54% (19.03) (n=23) | 44.44% (6.90) (n=8) | 46.76% (16.32) (n=7) | 51.72% (n/a) (n=1) | 51.22% (20.51) (n=13) | W: 33.52% (n/a), E: 30.81%(n/a) (n=1) |
| Grade 3 tumours, median (IQR) | 38.68% (15.04) (n=58) | 33.76% (16.40) (n=27) | 41.11% (13.92) (n=8) | 39.53% (16.90) (n=7) | 47.13% (n/a) (n=1) | 38.83% (18.89) (n=14) | W: 56.92% (n/a), E: 43.95%(n/a) (n=1) |
| Positive lymph node status, median (IQR) | 64.68% (20.99) (n=42) | 58.50% (15.40) (n=23) | 70.53% (11.91) (n=6) | 64.66% (28.00) (n=3) | Not investigated | 91.38% (25.07) (n=10) | Not investigated |
| Premenopausal, median (IQR) | 58.86% (18.16) (n=30) | 58.40% (13.87) (n=13) | 57.00% (17.19) (n=5) | 37.10% (n/a) (n=1) | 60.92% (n/a) (n=1) | 68.48% (17.26) (n=7) | Not investigated |
| TNBC frequency, median (IQR) | 25.00% (19.41) (n=67) | 23.00% (9.02) (n=29) | 25.00% (13.08) (n=10) | 20.43% (7.32) (n=8) | 14.94% (n/a) (n=1) | 49.4% (13.60)(n=17) | n/a |
*Two studies investigated both West and East African populations in their respective manuscripts.
E, East African participants; n/a, not applicable; W, West African participants.