Treatment of advanced or recurrent
breast cancer with
medroxyprogesterone acetate (MPA) shows high response rates and the accessory effects of appetite stimulation, improvement in performance status (PS) and bone marrow protection. In recent years,
interleukin-6 (IL-6) has been reported to cause
cachexia. In this study, to clarify the significance of
IL-6 in advanced or recurrent
breast cancer, the relationship between the
IL-6 level and clinical findings or effect of MPA was investigated. Sixty-five patients with recurrent or advanced
breast cancer participated in a prospective study. The age of patients ranged from 28 to 79 years with an average age of 51.3 years.
IL-6 level was investigated in these patients dosed with 800 mg/day of MPA and in 17 postoperative nonrecurrent patients. Serum MPA level was measured by high-performance liquid chromatography and
IL-6 level was measured prior to MPA administration, 4 weeks (in 59 cases) and 12 weeks (in 32 patients) after MPA administration by ELISA. Serum
IL-6 level was significantly higher in recurrent cases, especially in those with visceral
metastasis. Further, in patients for whom MPA
therapy was effective, the
IL-6 level prior to the treatment was clearly low. The
IL-6 level was significantly increased after 4 weeks. However, response to MPA was significantly higher and PS was improved in those cases demonstrating less increased
IL-6 levels after 4 weeks. In addition, the effect of MPA was significantly related to a higher serum concentration of MPA-positive ER, and longer disease-free interval, although there was no significant predictive factor for the clinical effect of MPA
therapy in multivariate analysis. In conclusion, MPA
therapy was effective in cases demonstrating a low
IL-6 level and less increased
IL-6 levels after 4 weeks. PS was improved in those cases in which the degree of
IL-6 increase was suppressed by MPA, and many such cases showed low
IL-6 levels prior to MPA
therapy. Furthermore, PS was improved even in nonresponders to MPA. Therefore, it is suggested that MPA
therapy might be useful in treating recurrent
breast cancer, and its benefits might be mediated by
IL-6.