Good morning! I appreciate this forum!
I'm starting Femara (letrozole) after dozens of hours of researching AI's. I was trying to understand if taking an AI is worth the side effects for someone with stage/grade 1 invasive ductal carcinoma. I mostly read scholarly articles on the US National Institutes of Health website to better understand each drug's safety and efficacy. But I could not find research showing their effectiveness vs not taking them (placebo). This is because AI's are not typically compared to a placebo, but are compared to Tamoxifen. I'm continuing to look and appreciate if anyone finds a scientific study comparing the effectiveness of taking an AI vs. placebo.

The most useful info I found regarding side effects was from a pharmacist who provided the FDA website with the manufacturers product information. Here are the links to the pdf's. I printed each of these (28-38 pages) and compared each of the drugs and categories side by side.
Arimidex (anastrozole), non-steroid: https://www.accessdata.fda.gov/drugsatfda_docs/label/2011/020541s026lbl.pdf
Aromasin (exemestane), steroid: https://www.accessdata.fda.gov/drugsatfda_docs/label/2011/020753s009s011s012lbl.pdf
Femara (letrozole), non-steroid: https://www.accessdata.fda.gov/drugsatfda_docs/label/2014/020726s027lbl.pdf
Hope this helps.