PTEN activity could be a predictive marker of trastuzumab efficacy in the treatment of ErbB2-overexpressing breast cancer.

Trastuzumab is the only HER2/neu-directed therapy to have received Food and Drug Administration approval for the treatment of patients with metastatic breast cancer. The efficacy of trastuzumab depends on the HER2/neu status of the tumour and the patient's prior treatment, but even when patients are selected on the basis of HER2/neu gene amplification, the single-agent response rate ranges from 12 to 30% and few patients respond to trastuzumab monotherapy. Here, we propose PTEN as a predictive biomarker for trastuzumab efficacy. Human breast cancer SKBR3 and drug-resistant SKBR3/R cells were investigated. We also examined clinical samples from patients who had been treated with trastuzumab and analysed the relationship between trastuzumab efficacy and PTEN level. The PI3K/Akt signalling pathway was observed to be highly active in the drug-resistant cells, and their level of PTEN was low. Delivery of antisense PTEN duplex siRNA significantly decreased the trastuzumab chemosensitivity of parental SKBR3 cells, and marked activation of Akt signalling pathway was also recognised. Moreover, immunohistochemical investigation revealed that trastuzumab treatment was remarkably successful in cells with elevated PTEN expression. Along with the immune-system-associated cytotoxic mechanism, several mechanisms have been proposed for the effect of trastuzumab. PTEN activity might play an important and major role in its HER2/PI3K/Akt-mediated antitumour effect, and could be a useful biomarker for predicting the efficacy of trastuzumab in the treatment of breast cancer.

Gasless endoscopic thyroid and parathyroid surgery using a new retractor.

Endoscopic thyroid and parathyroid surgery have now become feasible procedures, but the working space provided by the gasless technique is more limited than that of the CO2 insufflation technique. Gasless endoscopic surgery was performed in 20 patients with thyroid or parathyroid tumors. A newly designed retractor was used. Gasless endoscopic surgery was performed in all patients without conversion to conventional techniques. The recurrent laryngeal nerve was visualized and preserved in all patients. No recurrent nerve palsy was noted. The new retractor created a sufficient working space, and our results demonstrated the feasibility of this technique.