A new study has reported that the prognosis for breast cancer patients with HER2 overexpressing (HER2+) or triple negative disease is improved by chemotherapy even when the tumors are only 1 cm in size and the axillary lymph nodes are negative for breast cancer. The study was designed to investigate whether human epidermal growth factor receptor 2 (HER2) status is an independent, poor prognostic marker in patients with small (1 cm), lymph node-negative tumors. The authors also sought to identify a subgroup of patients with small tumors who might benefit from adjuvant chemotherapy. Long-term outcomes and hence the appropriateness of adjuvant therapy in patients with small, node-negative breast cancer have not been established. The study included all 421 breast cancer patients with lymph node-negative tumors measuring 1 cm and with available HER2 status during 2001 to 2005 at the three Mayo Clinic sites. The patients were divided into three groups (HER2-, HER2+, and triple negative tumors (ER-/PR-/HER2-). A total of 364 (86.5%) tumors were HER2-, 28 (6.7%) were HER2+, and 29 (6.9%) were triple negative. Follow-up data were available for 357, 28, and 28 patients in the three groups, respectively. The median follow-up time was 1,015 days (range: 1 to 2,549 days). Eleven (3.0%) of the patients with HER2-, seven (25.0%) with HER2+, and eight (27.6%) with triple negative tumors underwent chemotherapy after surgery.

Breast cancer recurred in nine patients during follow-up: four were HER2- (1.1% of the HER2- patients), two were HER2+ (7.1% of the HER2+ patients), and three were triple negative (10.7% of the triple negative patients). The authors conclude that breast cancer patients with small, node-negative primary tumors have an excellent prognosis, but HER2+ and triple negative tumors appear to have a higher recurrence rate, and should be considered for chemotherapy.

Please see our articles on HER2 positive prognosis and triple negative prognosis.