After a median follow-up of 86.5 months, patients with HR+/HER2− BC in the SCAN-B cohort (n = 5441) showed a significant association between high TACSTD2 expression level and ILC histological type (P = .0064), low histological grade (P < .0001), early tumor stage (P < .0001), and smaller tumor size (<20 mm, P < .0001). This evidence concerns the gene TACSTD2 and breast cancer.