[Relationship between the response of breast cancer to neoadjuvant chemotherapy and PI3K/mTOR pathway]

To explore the relationship between the status of PI3K/mTOR pathway and the therapeutic efficacies of neoadjuvant chemotherapy for breast cancer.

A total of 105 patients receiving 4-6 cycles of taxane-based neoadjuvant chemotherapy at our centre between January 2009 and November 2010 were recruited into this retrospective study. The expressions of PTEN, p-AKT (Ser473) and p-mTOR (Ser2448) were detected by immunohistochemistry before neoadjuvant chemotherapy. We employed pathology to evaluate the therapeutic efficacies and considered complete response (G4) & pathologic complete response (PCR) as efficacious. Fourfold table Chi-square test and binary Logistic regression were used to analyze the relationship between the above features and therapeutic efficacies.

The overall efficacy rate of neoadjuvant chemotherapy was 58.1% (61/105) and the PCR rate 27.6% (29/105). The positive expression rates of PTEN, p-AKT and p-mTOR were 52.4% (57/105), 68.6% (72/105) and 43.8% (46/105) respectively. Fourfold table Chi-square test showed the difference between p-mTOR and therapeutic efficacy was significant statistically (P = 0.003) and also the difference between p-mTOR and PCR (P = 0.001). Binary Logistic regression showed the difference between p-mTOR and therapeutic efficiency was significant statistically, and also the difference between p-mTOR and PCR (both P < 0.01). The differential expressions of p-mTOR and p-AKT were statistically significant (P = 0.000) and so were those of p-AKT and PR (P = 0.035).

The status of p-mTOR has predictive values for taxane-based neoadjuvant chemotherapy. The patients with a low level of p-mTOR are more responsive to thermotherapy while those with a high level of p-mTOR have a worse efficacy.