Lymphocytic Infiltrates May Be Tied to Breast Cancer Survival
NEW YORK (Reuters Health) – High levels of stromal tumor-infiltrating lymphocytes (STILs) are associated with improved recurrence-free survival (RFS) in early-stage human epidermal growth factor receptor 2 (HER2) positive breast cancer patients treated with chemotherapy, according to an exploratory ad hoc analysis.
However, in an October 15 online paper in JAMA Oncology, Dr. Edith A. Perez of the Mayo Clinic, Jacksonville, Florida, and colleagues report that this is not the case in such patients who also receive trastuzumab.
The team came to this conclusion after examining data on 489 clinical trial subjects who received standard chemotherapy with doxorubicin-cyclophosphamide followed by weekly paclitaxel. They were compared with a further 456 who got doxorubicin-cyclophosphamide followed by weekly paclitaxel plus trastuzumab followed by trastuzumab alone.
Tumors were classified as lymphocyte-predominant breast cancer (LPBC) if they consisted of at least 60% STILs. In all, 94 patients were deemed LPBC and 851 were non-LPBC.
After a median follow-up of 4.4 years, estimates of 10-year RFS in standard chemotherapy patients with high levels of STILs were 90.9%. For low levels, they were 64.3%.
However, in the trastuzumab patients, STILs levels had no prognostic association. For high levels estimated 10-year RFS was 80.0% and for low levels the corresponding proportion was 79.6%.
Multivariable analysis confirmed the significant association of STIL status and RFS in the standard group and its lack of significant in trastuzumab patients.
However, there were 154 disease recurrence events in the non-LPBC group compared to only eight in the LPBC group, meaning, the investigators wrote, “that this study was likely underpowered to detect a treatment effect in this group.”
Nevertheless, they concluded, “The trastuzumab treatment effect does appear to differ by LPBC status; at the very least, the trastuzumab effect in the patients with LPBC appears to be less than that in those without LPBC.”
In an accompanying editorial Dr. Sylvia Adams of New York University School of Medicine points out that these findings contradict those of other researchers who showed better outcomes with increasing STILs levels in patients receiving trastuzumab.
“Clearly,” she concluded, “these contradictory predictive findings require further study and evaluation of additional data sets.”
Dr. Perez was unavailable for comment.
SOURCE: http://bit.ly/1KkwF6G and http://bit.ly/1PuF7bB
JAMA Oncol 2015.