The relationship between the nuclear grade and subtypes. Grade 1 tumors were detected in 47.7% of the 111 luminal A subtype tumors, 15.8% of the 95 luminal B (HER2-) subtypes, 8.7% of the 69 luminal B (HER2+) subtypes, 0% of the 41 HER2 subtypes, and 8.5% of the 47 basal-like subtype tumors. Of the grade1 tumors 67.9% were categorized as part of the luminal A subtype. Grade 3 tumors were detected in 18.0% of luminal A tumors, 58.9% of luminal B (HER2-), 75.4% of luminal B (HER2+), 92.7% of HER2, and 85.1% of basal-like tumors. In the HER2 and basal-like subtypes, grade3 tumors were common but grade 1 tumors are rare. In contrast, the luminal A and luminal B (HER2-) subtypes consisted of heterogeneous populations with different grade. Solid square; grade 1 tumors, cross; grade 2 tumors, and solid circle; grade 3 tumors.