Higher Distant Invasive Breast Cancer Recurrence Risk for HER2-Positive T1b vs T1a Node-Negative Localized Breast Cancer
In a study of data from an integrated health-care delivery system reported in the Journal of Clinical Oncology, Fehrenbacher et al found that patients with T1b node-negative localized breast cancer have a higher risk of distant invasive recurrence than those with T1a disease. Risk was highest among patients with T1b tumors reported at 1.0 cm.
Study Details
In the study, assessment of data from 16,975 consecutive patients with invasive breast cancer diagnosed between January 2000 and December 2006 in a large integrated health-care system (Kaiser Permanente Clinical Care Program of Northern California) revealed a cohort of 234 with HER2-positive T1a, N0, M0 or T1b, N0, M0 (T1ab, N0, M0) disease. Median follow-up of this cohort was 5.8 years. A total of 15 invasive recurrences were identified, of which 7 were locoregional only. T1b tumors reported at 1.0 cm accounted for 24% of the T1ab cohort, 61% of the cohort total tumor volume, and 75% of distant recurrences.
Recurrence Rates
Among 171 T1ab patients not treated with adjuvant trastuzumab (Herceptin) or chemotherapy, the 5-year invasive distant recurrence–free rates were 98.2% overall, 99.0% in T1a patients, 97.0% in all T1b patients, and 93.3% in patients with T1b 1.0-cm tumors. The 5-year locoregional plus invasive distant recurrence-free rates were 97.0% in T1a patients, 91.9% in all T1b patients, and 89.4% in patients with T1b 1.0-cm tumors.
Among all patients (treated and not treated with chemotherapy or trastuzumab), the 5-year invasive distant recurrence–free rates were 99.1% in T1a patients, 93.9% in all T1b patients, and 87.0% in patients with T1b 1.0-cm tumors. The 5-year locoregional plus invasive distant recurrence–free rates were 97.4% in T1a patients, 90.9% in all T1b patients, and 84.5% in patients with T1b 1.0-cm tumors (P = .009 vs T1a).
The investigators concluded, “The distant [invasive recurrence] risk of T1a HER2-positive breast cancer appears quite low. The distant [invasive recurrence] risk in T1b patients, particularly those with 1.0 cm tumors, is higher. Potential risk differences for T1a and T1b, including the 1.0 cm tumors, should be considered when making treatment decisions.”
Louis Fehrenbacher, MD, of Kaiser Permanente, Vallejo, California, is the corresponding author for the Journal of Clinical Oncology article.
The study was supported by a grant from the Kaiser Foundation Health Plan Community Benefits fund. For full disclosures of the study authors, visit jco.ascopubs.org.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
