ESR1 and neoplasm: Young age at presentation (p < 0.001), WLE (p < 0.001), unfavorable tumor features, including a greater number of involved nodes (p = 0.004), higher tumor grade (p = 0.001), lymphovascular invasion (LVI) (p = 0.001), and estrogen receptor-negative status (p = 0.025) were positively associated with post-operative nodal radiation (Table 1).