Results: In univariate and multivariate analyses, the prognostic significance of PgR status among systemically untreated patients is modest. Among endocrine-treated patients, however, multivariate analyses, including lymphnode involvement, tumor size, and age, demonstrate that PgR status is independently associated with disease-free and overall survival. For recurrence, the reduction in relative risk (RR) was 25% for ER-positive/PgR-negative patients and 53% for ER-positive/PgR-positive patients, compared with ER-negative/PgR-negative patients (P<. 0001, PP patients). Patients with ER-positive/PgR-negative tumors have a reduction in RR of death of 30%(SPORE patients) and 38%(PP patients), compared with patients with ER-negative/PgR-negative tumors (P<. 0001). For ER-positive/PgR-positive tumors, the reduction of the risk of death was greater than 46% in SPORE patients and 58% in PP patients, indicating that ER-positive/PgR-positive patients derive more benefit from endocrine therapy (P<. 0001).

Conclusion: When accurately measured, PgR status is an independent predictive factor for benefit from adjuvant endocrine therapy. Therefore, PgR status should be taken into account when discussing RR reductions expected from endocrine treatment with individual patients.