PGR and breast cancer: In detail, subgroups 4 (PR low/Ki67 high), 3 (PR low/Ki67low) and 2 (PR high/Ki67 high) all displayed a significantly increased risk of BC-related death (HR=4.11; p=0.008; HR=3.43; p=0-007; HR=2.57; p=0.020, respectively) when compared to subgroup 1 (PR low/Ki67 low) (Table 4).