ESR1 and neoplasm: The positive ER (ER+) or PR (PR+) status was defined as the positive nuclear staining present among 1% or more of tumor cells.17 HER2 staining was classified according to the percentage of positively stained tumor cell nuclei and the intensity of nuclear staining, with “−” for no staining, “1+” for weak intensity, “2+” for intermediate intensity, and “3+” for strong intensity.18 The categories of “−” or “1+” were categorized as HER2‐negative expression (HER2−) and “3+” as positive expression (HER2+).