The optimal adjuvant management of T1a HER2-positive breast cancers is uncertain and requires an individualized approach, according to Hope S. Rugo, MD, Professor of Medicine and Director, Breast Oncology and Clinical Trials Education at the UCSF Helen Diller Family Comprehensive Cancer Center. “There is some controversial data looking at small HER2-positive tumors suggesting that the T1a tumors may have a very good prognosis, but that’s probably very much modified by ER [estrogen receptor] status,” she said.

For the ER-negative group, “we don’t have any data on the benefits of using trastuzumab [Herceptin] alone, and it may be that chemotherapy alone is sufficient, or no therapy,” Dr. Rugo commented. “You have to individualize your treatment choices based on the age of the patient and your level of concern. You have these anecdotes of a young patient with a 0.2-cm ER-negative, HER2-positive tumor who came back 18 months later with massive metastatic disease and was dead in months. So you don’t want to just dismiss it.… In a young patient, I usually do treat with a short course of something, even if they have a very small ER-negative, HER2-positive tumor. I have found that in my cyber-tumor boards that generally, my colleagues do as well.”

 For the ER-positive group, “we don’t really know how to treat those patients either,” Dr. Rugo commented. “In ER-positive T1a tumors, I tend to use hormone therapy and not use any directed therapy.” Oncologists may occasionally want to consider obtaining an Oncotype DX recurrence score or Mammaprint score, for example, in a patient with relative contraindications to therapy. “There can be unusual situations where it might help direct you a little bit,” she said. ■

Disclosure: Dr. Rugo has received research funding from Abraxis BioScience, Bristol-Myers Squibb, and Roche/Genentech.