Short-term effects of anastrozole treatment on insulin-like growth factor system
Insulin-like growth factors (IGFs) play a fundamental role in cancer development by acting in both an endocrinal and paracrinal manner, and hormone breast cancer treatments affect the IGF system by modifying circulating growth factor levels. We evaluated total IGF-1, IGF-2, IGF binding protein (IGFBP)-1 and IGFBP-3 in the blood of 34 postmenopausal advanced breast cancer patients (median age 63 years, range 41-85) treated with anastrozole, a non-steroidal structure aromatase inhibitor (NSS-AI). The plasma samples were obtained at baseline, and after 2, 4, 8 and 12 weeks of treatment. The IGFs were quantitated by means of sensitive radioimmunoassays (RIAs). IGF-1 significantly increased during anastrozole treatment (baseline versus 12 weeks, P=0.031), IGF-2 showed a trend towards an increase, and IGFBP-1 constantly but not significantly decreased; IGFBP-3 did not seem to be affected at all. The anastrozole-induced changes in IGFs and IGFBP-1 appeared to be different in the patients receiving a clinical benefit from those observed in non-responders. We have previously shown that letrozole (a different type of NSS-AI) modifies blood IGF-1 levels, and the results of this study of the biological effects of anastrozole on the components of the IGF system confirm our previous observations.
Thats only the abstract but it shows how Adex can actually increase IGF-1 in the short term. Actually I read that in a couple profiles comparing it to nolvadex. Now I found people saying it lowers IGF-1 which got me thinking I should stop using it. That being said there is no evidence but Bros science claiming it lowers IGF-1 in different forums, and no one backs it up with an actual study. If someone has a study about the effects of Adex on IGF-1 please post it here. I just don't think repeating what other guys said in another forum helps to know the truth about these AI's.
Apparently all AI's increase IGF-1. Possibly Femara more than the rest. That being said this makes more sense because if Aromasin and Femara both are known to raise IGF-1 and they are AI, then Arimidex which is also an AI should have the same effect. Nolvadex which is known to lower IGF-1 is a SERM and has a different way of suppressing estrogen.