Adjuvant therapy may extend survival in early breast cancer with micrometastases

NEW YORK (Reuters Health) - Women with favorable early-stage breast cancer may benefit from systemic adjuvant therapy when isolated tumor cells or micrometastases are found in regional lymph nodes, a research team in the Netherlands reports in the August 13th issue of The New England Journal of Medicine.

"The Dutch guidelines regarding the treatment of breast cancer do not recommend systemic adjuvant therapy for low-risk breast cancer with isolated tumor cells in a regional lymph node," according to Dr. Vivianne C. G. Tjan-Heijnen from Maastricht University Medical Center and co-authors. The guidelines do not address the issue in cases of low-risk breast cancer with nodal micrometastases.

Investigators in the MIRROR (Micrometastases and Isolated tumor cells: Relevant and Robust Or Rubbish?) study used the Netherlands Cancer Registry to identify women who had undergone a sentinel-node biopsy before 2006.

Included were 995 patients with isolated tumor cells or micrometastases who underwent adjuvant therapy, along with 856 randomly-selected node-negative patients and 856 node-positive patients who did not.

Pathologists reviewed all available original slides of the sentinel and other positive nodes. Isolated tumor cells were defined as deposits of 0.2 mm or less, and micrometastases as deposits > 0.2 mm but no larger than 2.0 mm.

The 5-year rate of disease-free survival was significantly lower in the node-positive, no-adjuvant-therapy cohort than in the node-negative group (76.5% vs 85.7%, p < 0.001). After adjusting for prognostic clinical and pathological variables, the hazard ratio for recurrence was 1.51.

In node-positive patients who did receive adjuvant therapy compared with node-positive patients who did not, the adjusted hazard ratio was 0.57.

The results were similar for isolated tumor cells and for micrometastases.

"In current staging systems for breast cancer...nodes containing isolated tumor cells are classified as node-negative," the authors write. Based on these findings, a reevaluation of treatment guidelines is warranted.

N Engl J Med 2009;361:653-663.

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