We have previously shown the prognostic importance of tumor-infiltrating lymphocytes (TILs) in newly diagnosed triple-negative breast cancer (TNBC) using tumor samples from a large clinical trial cohort. In this study, we aimed to validate these findings and also investigate associations with trastuzumab benefit in HER2-overexpressing disease (HER2+). A prospective–retrospective study was conducted using samples from the FinHER adjuvant, phase III trial that enrolled 1010 early-stage BC patients, 778 of whom were HER2-nonamplified. Those with HER2+ disease (n = 232) were randomized to 9 weeks of trastuzumab or no trastuzumab in addition to chemotherapy. Two pathologists independently quantified stromal TILs in 935 (92.6%) available slides. The primary end point of distant disease-free survival (DDFS) and interactions with trastuzumab were studied in Cox regression models. Confirming our previous findings, in TNBC (n = 134) each 10% increase in TILs was significantly associated with decreased distant recurrence in TNBC; for DDFS the hazard ratio adjusted for clinicopathological factors: 0.77; 95% confidence interval (CI) 0.61–0.98, P = 0.02. In HER2+ BC (n = 209), each 10% increase in lymphocytic infiltration was significantly associated with decreased distant recurrence in patients randomized to the trastuzumab arm (DDFS P_interaction = 0.025). Higher levels of TILs present at diagnosis were significantly associated with decreased distant recurrence rates in primary TNBC. These results confirm our previous data and further support that TILs should be considered as a robust prognostic factor in this BC subtype. We also report for the first time an association between higher levels of TILs and increased trastuzumab benefit in HER2+ disease. Further research into why some TN and HER2+ BCs can or cannot generate a host antitumor immune response and how trastuzumab can favorably alter the immune microenvironment is warranted.

We compared docetaxel with vinorelbine for the adjuvant treatment of early breast cancer. Women with tumors that overexpressed HER2/neu were also assigned to receive concomitant treatment with trastuzumab or no such treatment. We randomly assigned 1010 women with axillary-node–positive or high-risk node-negative cancer to receive three cycles of docetaxel or vinorelbine, followed by (in both groups) three cycles of fluorouracil, epirubicin, and cyclophosphamide. The 232 women whose tumors had an amplified HER2/neu gene were further assigned to receive or not to receive nine weekly trastuzumab infusions. The primary end point was recurrence-free survival. Recurrence-free survival at three years was better with docetaxel than with vinorelbine (91 percent vs. 86 percent; hazard ratio for recurrence or death, 0.58; 95 percent confidence interval, 0.40 to 0.85; P=0.005), but overall survival did not differ between the groups (P=0.15). Within the subgroup of patients who had HER2/neu-positive cancer, those who received trastuzumab had better three-year recurrence-free survival than those who did not receive the antibody (89 percent vs. 78 percent; hazard ratio for recurrence or death, 0.42; 95 percent confidence interval, 0.21 to 0.83; P=0.01). Docetaxel was associated with more adverse effects than was vinorelbine. Trastuzumab was not associated with decreased left ventricular ejection fraction or cardiac failure. Adjuvant treatment with docetaxel, as compared with vinorelbine, improves recurrence-free survival in women with early breast cancer. A short course of trastuzumab administered concomitantly with docetaxel or vinorelbine is effective in women with breast cancer who have an amplified HER2/neu gene. (International Standard Randomised Controlled Trial number, ISRCTN76560285.)