Although HE4 expression did not correlate with recurrence in DCIS patients, both mRNA and protein levels were significantly associated with favorable prognostic and predictive features, including absence of comedonecrosis, low stromal TIL density, ER positivity, HER2 negativity, and the HR+/HER2− molecular subtype. The gene discussed is ESR1; the disease is ductal breast carcinoma in situ.