Prognostic markers in triple-negative breast cancer identified
NEW YORK (Reuters Health) - Clinicians from the UK say they have "robust data" to support routine assessment of basal cytokeratins and androgen receptors, in addition to traditional pathologic parameters (tumor size and lymph node status), in women with triple-negative breast cancer.
This additional information yields useful prognostic information that can help guide treatment decisions, the researchers report in the January 1 issue of Cancer.
"Triple-negative breast cancer (estrogen receptor-negative, progesterone receptor-negative, and HER2-negative) is a high risk breast cancer that lacks the benefit of specific therapy that targets these proteins," note Dr. Emad Rakha and colleagues from the University of Nottingham.
To identify prognostic markers that might signal more aggressive behavior of these specific tumors, the researchers examined a series of 1,944 well characterized invasive breast carcinomas with a median clinical follow up of 56 months.
Among 1,726 "informative cases," 282 (16.3%) were of the triple-negative phenotype and formed the basis of the study.
Most triple-negative tumors, Rakha and colleagues report, were grade 3 ductal carcinomas of no specific type.
The absence of androgen receptor expression, seen in 234 triple-negative tumors (87%), was associated with higher histological grade, development of recurrences and distant metastasis, they observed. Higher grade was also associated with loss of E-cadherin expression and positive expression of basal cytokeratins, P-cadherin, p-53, and EGFR.
"Interestingly," write the authors, basal phenotype, as defined by the expression of CK5/6 and/or CK14 in 10% or greater of tumor cells, was detected in 55.7% of triple-negative tumors. In the lymph node-negative subgroup (63% of cases), basal phenotype was the sole prognostic marker identified in this subgroup.
"In these tumors, basal phenotype was associated with a poorer outcome, and thus, can define a group of patients that may benefit from a more aggressive therapeutic intervention," they conclude.
Cancer 2007;109:25-32.