ERBB2 and neoplasm: The resulting CART model revealed four risk layers based on SUVmax, tumor size, and molecular subtype: group 1 (SUVmax ≤6.75 and tumor size ≤2.0 cm); group 2 (SUVmax ≤6.75, tumor size >2.0 cm, and LumA or TN); group 3 (SUVmax ≤6.75, tumor size >2.0 cm, and LumB or HER2‐enriched); group 4 (SUVmax >6.75) (Fig. 3).