ERBB2 and breast cancer: For example, surface Hsp90 expression may be a useful surrogate marker for tumor infiltrating lymphocytes (TILs), which are of particular importance, as increased density of TILs in patients with early stage Her2+ breast cancer showed increased pathological complete response (pCR) when treated with standard-of-care therapies trastuzumab and/or lapatinib32,33.