Metastases that were 2 millimeters or less in diameter ("micrometastases") in axillary lymph nodes detected on examination of a single section of the lymph nodes were associated with poorer disease-free and overall survival in breast cancer patients, according to a new study published online February 26 in the Journal of the National Cancer Institute.
The prognostic relevance of isolated tumor cells and micrometastases in lymph nodes in breast cancer patients has become a major issue since the introduction of the sentinel lymph node procedure. Recently, patients with minimal lymph node involvement detected after a sentinel node procedure in the Dutch MIRROR study were found to have a reduced disease-free survival.
To better understand this issue, Maaike de Boer, M.D., and Vivianne C.G. Tjan-Heijnen, M.D., Ph.D., Division of Medical Oncology, at Maastricht University Medical Centre, the Netherlands, and colleagues performed a systematic review of literature published between 1977 and 2008 on the association of isolated tumor cells and micrometastases in axillary lymph nodes and survival. A total of 58 articles were included and divided into three categories according to the methods used to detect the small metastases: cohort studies with single-section pathological examination of axillary lymph nodes; occult metastases studies with retrospective examination of negative lymph nodes by step sectioning and/or immunohistochemistry; and sentinel lymph node biopsy studies with intensified work-up of the sentinel but not of the non-sentinel lymph nodes.
The presence (vs. the absence) of metastases that were 2 mm or less in diameter was associated with poorer overall survival among cohort studies and with poorer overall survival and poorer disease-free survival among occult metastases studies.