Insulin resistance in patients with advanced prostate cancer undergoing intermittent or continuous androgen blockade

Androgen blockade is the principle strategy in the treatment of advanced prostate cancer. Impaired glucose tolerance often occurs in those patients after androgen blockade. This study was to investigate the correlation of insulin resistance to intermittent androgen blockade (IAB) or continuous androgen blockade, which is also named surgical castration, in patients with advanced prostate cancer.

A total of 139 patients with advanced prostate cancer were classified into four groups according to the body mass index (BMI) and the treatment method. Group A consisted of 30 patients receiving surgical castration with BMI >or= 24 kg/m(2), group B consisted of 32 patients treated with IAB with BMI >or= kg/m(2), group C consisted of 37 patients undergoing surgical castration with BMI < 24 kg/m(2), group D consisted of 40 patients treated by IAB with BMI < 24 kg/m(2). Fasting plasma glucose (FPG) and fasting serum level of insulin (FINS) were assessed before treatment, six months and 12 months after treatment, respectively. Insulin resistance index (IRI) was also calculated.

Six months after treatment, FINS and IRI were all increased in the four groups compared with those before treatment; FINS and IRI were significantly higher in groups B and D than in A and C (FINS: t(A:B)=7.7516, p < 0.01, t(C:D)=4.8078, p < 0.01; IRI: t(A:B) =7.3671, p < 0.01, t(C:D)=5.1005, p < 0.01). Twelve months after treatment, which was the intermittent period of the IAB method, FINS returned to the pretreatment level in group D (q=2.5255, p > 0.05), and dramatically decreased in group B compared to the value six months after treatment (q = 9.0942, p < 0.01); in contrast, FINS and IRI remained unchanged in groups A and C.

Androgen blockade promotes insulin resistance in patients with advanced prostate cancer. Insulin resistance gradually disappears during the intermittent period of IAB.