In a nutshell
This study evaluated the prognosis of pT1a-bN0M0 breast cancer patients according to tumor subtype, and the survival benefit associated with adjuvant trastuzumab for those patients with HER2+status.
Some background
Breast cancer is extremely heterogeneous, meaning that the same disease can have many different origins. pT1a-bN0M0 breast cancer patients are those with small (less than 1cm) tumors that have not spread to regional lymph nodes or other organs, indicating an early stage disease. pT1a-bN0M0 breast cancer patients usually have a favorable prognosis. However, relapse and death do occur, particularly in those with human epidermal growth factor receptor 2 (HER2) positive tumors. While HER2-positive status has been associated with worse outcomes in pT1a-bN0M0 patients, targeted HER2 therapies, such as trastuzumab (Herceptin) have been proven to improve survival in multiple clinical trials. However, pT1a-bN0M0 patients are rarely included in these trials, and the effect of trastuzumab on the outcome of these patients remains unclear. This study assessed the prognosis of different pT1a-bN0M0 subtypes, and the survival benefits associated with adjuvant (additional) trastuzumab therapy.
Methods & findings
Eight studies, including more than 2500 patients, were included in this analysis. Breast cancer subtypes were grouped according to HER2 and hormone receptor (HR) status; HER2-positive (HER2+), HR-positive (HR+), HER2-negative (HR+/HER2-) and triple negative cancer (HR-/HER2-).
HER2-positive status was found to induce a negative effect on disease-free survival (the length of time between treatment and disease recurrence), and distant disease-free survival (the length of time between treatment and the spread of cancer to other organs), compared to HR+/HER2-. Prognosis was similar among HER2-positive patients and triple negative breast cancer patients.
The addition of trastuzumab to the treatment of HER2-positive pT1a-bN0M0 patients was found to significantly reduce the risk of disease progression and local recurrence. However, trastuzumab treatment among pT1a-bN0M0 patients failed to lower the risk of overall mortality and distant metastatic recurrence.
The bottom line
The study concluded that adjuvant trastuzumab treatment among HER2-positive pT1a-bN0M0 patients results in significant clinical benefits.
The fine print
All data was from non-randomized retrospective trials, and the number of trials used was small.
Published By :
PLOS ONE
Date :
Jan 02, 2014
