A B S T R A C T PurposeWe evaluated whether patients with human epidermal growth factor receptor 2 (HER2) -positive primary breast tumors had metastatic tumors that were HER2 positive (concordant) or HER2 negative (discordant). We then evaluated whether treatment with trastuzumab or chemotherapy before biopsy of the metastasis had any effect on the rate of HER2 discordance. We also compared the overall survival durations of patients with HER2-concordant and -discordant tumors.
Patients and MethodsWe retrospectively identified all patients who initially had been diagnosed with HER2-positive (immunohistochemistry 3ϩ and/or fluorescent in situ hybridization positive) primary breast cancer between 1997 and 2008 at MD Anderson Cancer Center who also had metastatic tumor biopsy results available for review.
ResultsWe included 182 patients who met our criteria. Forty-three (24%) of the 182 patients with HER2-positive primary tumors had HER2-negative metastatic tumors. The HER2 discordance rates differed significantly on the basis of whether patients received chemotherapy (P ϭ .022) but not on the basis of whether patients received trastuzumab (P ϭ .296). Patients with discordant HER2 status had shorter overall survival than did patients with concordant HER2 status (hazard ratio [HR], 0.43; P ϭ .003). A survival difference remained among the 67 patients who received trastuzumab (HR, 0.56; P ϭ .083) and 101 patients who did not (HR, 0.53; P ϭ .033) before their metastasis biopsies.
ConclusionWe confirmed that loss of HER2-positive status in metastatic tumors can occur in patients with primary HER2-positive breast cancer. Our data strongly support the need for biopsies of metastatic lesions to accurately determine patient prognosis and appropriate use of targeted therapy.
To define prognostic factors for breast cancer patients with brain metastases, compare their clinical courses and prognoses according to breast cancer subtypes, and analyze the causes of death in such patients. We retrospectively analyzed 1,466 patients diagnosed with brain metastases between April 1, 2001 and December 31, 2012, from 24 institutions of the Japan Clinical Oncology Group. Overall, 1,256 patients with brain metastases were included. The median overall survival (OS) was 8.7 months (95 % confidence interval [CI] 7.8-9.6 months). Univariate and multivariate analyses revealed that patients diagnosed with brain metastasis within 6 months of metastatic breast cancer diagnoses, asymptomatic brain disease, or HER2-positive/estrogen receptor-positive tumors had increased OS. Median OS after the development of brain metastases was 9.3 months (95 % CI 7.2-11.3) for the luminal type, 16.5 months (95 % CI 11.9-21.1) for the luminal-HER2 type, 11.5 months (95 % CI 9.1-13.8) for the HER2 type, and 4.9 months (95 % CI 3.9-5.9) for the triple-negative type. Luminal-HER2 type patients had significantly longer OS than patients with the luminal type (hazard ratio [HR] = 1.50, P < 0.0001) and triple-negative type (HR = 1.97, P < 0.0001); no significant differences were noted compared to HER2-type patients (HR = 1.19, P = 0.117). The prognosis and clinical course of patients with brain metastasis from breast cancer before and after developing brain metastases vary according to subtype. Focusing on the subtypes of breast cancer can optimize the prevention, early detection, and improved treatment of brain metastases.
We confirmed that loss of HER2-positive status can occur after neoadjuvant treatment in patients with primary HER2-positive breast cancer. We also confirmed that in practice, differences in pCR rates between breast cancer subtypes are the same as in clinical trials. Our data strongly support the need for retest ER, PgR, HER2 of surgical sample after neoadjuvant therapy in order to accurately determine appropriate use of targeted therapy.
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