"In an era of personalized medical therapy, the addition of biologic information to the standardized anatomic TNM staging system for breast cancer improves prognostic accuracy.
In an article in JAMA Surgery (2013 Dec 4. [Epub ahead of print], PMID: 24306257), Sanjay P. Bagaria, MD, and his co-authors made the case for adding biomarkers to the American Joint Committee on Cancer (AJCC) breast cancer staging system. Others have previously proposed including non-anatomic factors to classify patient disease status.
AJCC has resisted revisions to the system, citing cost and lack of resources to include multigene expression assays in some lower-income countries. The authors found that the test for triple-negative phenotype (TNP), defined by negative expression of estrogen receptor (ER), progesterone receptor (PR), and HER2, is simple, relatively inexpensive and available. TNP accounts for 15% to 20% of breast cancers and is associated with a poor prognosis.
The authors pulled patient information and follow-up data for 1,842 patients with primary invasive ductal breast cancer whose ER, PR, and HER2 status were known. Of these patients, 280 with TNP breast cancer were identified. The five-year survival curves of the patients with TNP approximated the results of patients whose non-TNP breast cancer was one TNM stage higher. The five-year overall survival (OS) for stage I TNP was similar to stage II non-TNP (92.2% vs. 93.4%; P=0.63). Similarly, the five-year OS for stage II TNP was similar to stage III non-TNP (83.9% vs. 78.5%; P=0.57). The five-year OS for stage III TNP approached stage IV non-TNP (58.4% vs. 34.6%; P=0.76); and the five-year OS for stage IV TNP was 14.3%."