NEW YORK (Reuters Health) - In women treated for small (1 cm or less), node-negative breast cancers, HER2 positivity is strongly linked to recurrence and poorer disease-free survival, according to the results of two studies reported in the November 2nd online issue of the Journal of Clinical Oncology.
In the first study, Dr. Ana M. Gonzalez-Angulo, from MD Anderson Cancer Center, Houston, and colleagues assessed the outcomes of 965 women who were treated for T1a,bN0M0 breast cancers from 1990 to 2002.
Seventy-seven percent of subjects had hormone receptor-positive tumors and 10% had HER2-positive tumors. None of the subjects were treated with adjuvant chemotherapy or trastuzumab.
During a median follow-up period of 74 months, there were 72 recurrences. The 5-year recurrence-free survival rates for patients with HER2-positive and -negative tumors were 77.1% and 93.7%, respectively (p < 0.001). The corresponding 5-year distant recurrence-free survival rates were 86.4% and 97.2% (p < 0.001).
After accounting for hormone receptor status, T stage, and other factors, HER2 positivity increased the risks of overall and distant recurrence by 2.68- and 5.3-fold, respectively.
"Patients with HER2-positive T1a,bN0M0 tumors have a significant risk of relapse and should be considered for systemic, anti-HER2, adjuvant therapy," the researchers conclude.
The second study, by Dr. Giuseppe Curigliano from Istituto Europeo di Oncologia, Milan, Italy, and colleagues, was a similar investigation in 2130 women treated for T1a,bN0M0 from 1999 to 2006.
One hundred fifty women had HER2-positive tumors, including 79 with hormone receptor-positive tumors and 71 with hormone receptor-negative tumors. None of the patients received adjuvant trastuzumab.
During a median follow-up period of 4.6 years, HER2 positivity was tied to reduced disease-free survival for hormone receptor-positive tumors. With such tumors, the 5-year disease-free survival rates for HER2-positive and -negative tumors were 92% and 99%, respectively. With hormone receptor-negative tumors, the corresponding rates were 91% and 92%.
After accounting for pT1 stage, HER2 positivity in patients with hormone receptor-positive disease increased the risk of disease recurrence by 5.1-fold.
The absolute risk of recurrence at 5 years is low in patients with HER2 positive, T1a-b breast cancer, the authors conclude. Still, HER2 positivity coupled with hormone receptor positivity markedly increases the risk of recurrence, they add.
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