Ten-year analysis of ShortHER trial: association between tumor-infiltrating lymphocytes and survival in early HER2-positive breast cancer

It is not clear whether the level of tumor-infiltrating lymphocytes (TILs) is associated with survival outcomes in patients with HER2-positive early breast cancer, and whether it can guide adjuvant treatment de-escalation. In a ten-year follow-up analysis of the multicenter ShortHER randomized clinical trial in Italy, among 866 patients with availble TIL data, there was a statistically significant association between each 5% increase in TILs and improved overall survival. Patients with TILs 20% or higher did not have excess risk of death when treated with de-escalated chemotherapy and trastuzumab. The authors conclude that TILs can serve as a biomarker to identify patients with HER2-positive early breast cancer who may safely undergo de-escalated adjuvant therapy without compromising long-term survival outcomes (visual abstract).