A lower allred score for progesterone receptor is strongly associated with a higher recurrence score of 21-gene assay in breast cancer
Among the 77 infiltrating breast carcinomas, we found that progesterone receptor (PR) expression was inversely associated with recurrence score (RS, p < .0001). RS is also significantly associated with tubule formation, mitosis, and luminal B subtype. The equation of RS = 17.489 + 2.071 (tubal formation) + 2.926 (mitosis) –2.408 (PR) –1.061 (HER2) + 7.051 (luminal A) + 29.172 (luminal B) predicts RS with an R2 of 0.65. In conclusion, PR negativity, luminal B subtype, tubal formation, and mitosis are strongly correlated with a higher RS.