Characteristics and predictive factors of M-AS
All 67 patients reviewed with localized breast cancer were treated with FEC-D(T) chemotherapy regimen (three cycles of 5-fluorouracil (5FU), epirubicin, and cyclophosphamide followed by three cycles of docetaxel at a dose of 100 mg/m2 with or without trastuzumab). Nineteen patients developed M-AS following their first dose of docetaxel (Cycle 4 of FEC-D(T)). Of the 48 patients who did not develop the syndrome, three patients had been taking gabapentin or pregabalin at the time of their docetaxel treatment and hence are described separately. The remaining 45 patients were included in the control group for the current analysis. Tables 1 and 2 outline the characteristics of the M-AS and control group of patients and include details such as age, BSA, characteristics of the tumor (stage, histology, hormone receptor status), setting of treatment (neoadjuvant or adjuvant), and laboratory values (total bilirubin and calculated glomerular filtration rate as possible surrogates of drug metabolism capacity and platelet counts as a surrogate for baseline inflammatory status). Among all these, BSA was found to be higher in the M-AS group (mean 1.85 vs 1.71 in the control group using χ2 test, p=0.013; Table 1).
Other baseline characteristics of the patients in the two groups as well as concomitant medications or medical conditions that may play a role or may be associated with the development of M-AS were evaluated (Table 2). Development of peripheral neuropathy after docetaxel administration was more prevalent in the M-AS group (p=0.021), whereas the presence of a rheumatologic diagnosis (mainly osteoarthritis) or diabetes mellitus was not. Use of G-CSF at the start of docetaxel treatment (Cycle 4) was not associated with the M-AS (p=0.12). G-CSF had to have been started in prior cycles because start at Cycle 4 was an exclusion criterion. Use of statins, known to be associated with myalgias, or use of antidepressants was also not different in the two groups.