Don S. Dizon, MD, FACP, Clinical Co-Director of Gynecologic Oncology at Massachusetts General Hospital in Boston, MA, said, “in general, any woman with a HER2-positive breast cancer should receive trastuzumab during chemotherapy and then for 1 year. Now, we are trying to figure out if it’s all women, or if there is a subgroup of women with small tumors who will do well without it.”

He added, “on the one hand, you don’t want to lose the opportunity to cure someone; on the other, you don’t want to overtreat someone, either, with a year’s worth of trastuzumab. It’s an expensive proposition and increases the risk of heart failure as well, up to 5-fold.”

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Data from the APT study is the best “evidence-based data” of who will benefit from treatment, and Dr. Dizon said he agreed with the study authors’ conclusion that women with the smallest tumors, T1a, may not “need this much treatment, if they need treatment at all. I think the best approach is an individual one, taking into account the patient’s tumor, baseline medical condition, goals, and her preferences. There is no way to define an absolute threshold of who does not need to be treated based on tumor size.”

Based on the encouraging results of this trial, and with the goal of “trying to develop a more biologically based regimen and lower toxicities further,” in May 2013 Dr. Tolaney and colleagues initiated ATEMPT, a randomized phase 2 study of trastuzumab emtansine (T-DM1) versus paclitaxel plus trastuzumab for patients with stage 1 HER2-positive breast cancer, which is recruiting participants.3


  1. FDA approval for trastuzumab. National Cancer Institute. Available at: Updated July 3, 2013. Accessed March 4, 2015.
  2. Tolaney SM, Barry WT, Dang CT, et al. Adjuvant paclitaxel and trastuzumab for node-negative, HER2-positive breast cancer. N Engl J Med. 2015;372(2):134-141.
  3. T-DM1 vs Paclitaxel/Trastuzumab for Breast (ATEMPT Trial). Available at: Accessed March 4, 2015.