ERBB2 and breast cancer: Similar results were seen among patients with HER2‐negative breast cancer; an elevated risk of distant recurrence for patients with high PR intra‐tumor heterogeneity versus low was observed (Full model: HR = 1.43; 95% CI, 1.01–2.02, and Crude model: HR = 1.52; 95% CI, 1.07–2.15).