Patients with breast cancer whose tumors were HER2-positive and one centimeter or smaller had a significant risk of relapse compared with other tumor types, according to a new study presented at the CRTC-AACR San Antonio Breast
Cancer Symposium.

"The current guidelines call for no further therapy if the tumors are less than five millimeters or consider therapy if the tumors are from six to 10 millimeters, but this data challenges that thinking and shows this group of women may benefit from additional therapy," said Ana M. Gonzalez-Angulo, M.D., assistant professor in the Departments of Breast Medical Oncology and Systems Biology at the University of Texas M.D.
Anderson Cancer Center (MDACC).

Gonzalez-Angulo and Ronjay Rakkhit, chief fellow of Hematology-Oncology at M. D. Anderson, and colleagues retrospectively studied 965 patients from MDACC and validated their findings with 350 patients from two European institutions. Patients with a lack of receptor information, and/or who had received adjuvant chemotherapy or trastuzumab at any time were excluded.

"This is the largest study of its kind in a patient population, and as our ability to detect tumors improves, this patient population will only continue to increase. Further, it answers a common question oncologist have in daily practice - which early stage patients may be in need of additional therapy," said AMG.

Patients were diagnosed between 1990 and 2003. Median age of the patients at diagnosis was 57 years. All tumors were one centimeter or smaller. Most of the tumors (68 percent) were hormone receptor-positive, while 10 percent were HER2-positive and 23 percent were triple receptor-negative.

Five-year, recurrence-free survival was 77.1 percent and 93.7 percent in patients with HER2-positive and HER2-negative tumors, respectively, and five-year distant recurrence-free survival was 86.4 percent and 97.2 percent, in patients with HER2-positive and HER2-negative tumors, respectively. Patients with HER2-positive tumors had 2.68 times greater risk of recurrence and 5.3 times higher the risk of distant recurrence than those with HER2-negative tumors. Patients with HER2-positive tumors had 5.09 times the risk of recurrence and 7.81 times the risk of distant recurrence compared to patients with hormone receptor-positive tumors.

Data on 350 additional patients treated at two other institutions showed reproducibility, said Gonzalez.

"This paper shows that patients with HER2-positive tumors one centimeter or less have a significant risk of relapse and should be considered for clinical trials of systemic anti-
HER2 adjuvant therapy, or if a clinical trial is not available, adjuvant therapy should be discussed with them", said Gonzalez-Angulo.