Understanding Aromatase Inhibitors in Breast Cancer

Updated: Mar 6

Aromatase Inhibitors (AIs); If your tumor is hormonal driven, then these two words have probably been thrown at you and around you several times during and after your treatment journey. They are often referred to as the dreaded post-treatment drugs or even more colloquially as the “good/evil drugs”. For those who have no clue what AIs are and what they do, AIs are drugs associated with endocrine therapy. This type of treatment is used for breast cancers that are estrogen and/or progesterone positive.



That is why it is extremely important to maintain a healthy weight and engage in a consistent exercise routine which involves both cardio and strength training. It is recommended to do 30 minutes of exercise 5 days a week, (or a minimum of 150 minutes per week). If you are not currently in the habit of exercising, start off with a brisk walk a few times a week and work up from there.



Why Aromatase Inhibitors?


If your cancer is hormonally driven, your oncologist most likely will recommend taking this form of therapy for a period of time ranging from 5 to 10 years. Because these drugs block the development of estrogen in your body, it significantly decreases the changes of an ER+/PR+ cancer returning. Tumors which are negative for estrogen, progesterone and the HER2 protein do not respond to aromatase inhibitors and therefore hormonal therapy is not prescribed to those diagnosed with triple negative breast cancer (TNBC). This is where the colloquial phase “good evil drugs” come into play. Ask any TNBC thriver and they will say, “the good thing about being triple negative is that they don’t have to take drugs like tamoxifen or AI’s, but the bad thing about being triple negative is that they do not take drugs like tamoxifen or AI’s!”. The grass is always greener.


How do AI’s Work?


There are three aromatase inhibitors that have been FDA approved:

anastrozole (Arimidex®), letrozole (Femara®) and exemestane (Aromasin®). A breast cancer cell, on its surface has a lot of different receptors to bind with different chemical compounds within the body. One of the receptors it has is for estrogen/ progesterone. So basically, anytime some estrogen binds to that cell it causes that tumor to grow. The tumors are essentially fed by estrogen or progesterone. The AI drugs prevent this binding from happening by drastically minimizing the level estrogen/ progesterone produced and hence inhibit the cancerous growth.


Side Effects of AI’s


Now, this might seem well and dandy but the side effect of these AI drugs has proven to be no joking matter. Serious side effects such as heart problems and osteoporosis can be a result of this classification of drugs. Most cancer survivors experience intense joint pain, drastic bone loss, sudden weight gain, extreme fatigue, and loss in libido. These are just a few on the list. The one thing we all know is that most survivors react differently to the kind of treatments they are on. Women share how being on AI drugs has caused them crippling joint pain and stiffness. It’s not uncommon to hear our SBC community members joke about being young on the outside and feeling like 100 years old on the inside! These side effects are caused primarily by estrogen deprivation.

To help combat the side effects of osteoporosis, doctors may also prescribe Zometa. This is a drug that helps to prevent the weakening, breaking of bones, or any complications that may come from advanced staged breast cancer. In early stage breast cancer, Zometa has been proven to decrease the chance of the disease spreading to the bones.


As breast cancer survivors, we are usually content with anything our oncologists suggest as long as it prevents cancer from coming back or progresses further, even if it means we suffer the side effects. But with AI drugs, there has been some progress on how to battle these side effects. With the recent spotlight being shined upon AI drugs and the advancements in seeing how patients are reacting to it, treatment options can be tweaked to help lessen the side effects. Talk to your oncologists and see if he/she could switch you through the different AIs to see which one has the least amount of side effects for you. At the end of the day you must evaluate the quality of life you are living. These are important conversations to have with your medical care team and loved ones so that you can design a plan that is in YOUR best interest.


Personally, I was on all three of the AI’s until I landed on Letrozole. As noted earlier, everyone responds differently to this therapy. Unlike chemo, or radiation where the treatment plan felt more like a given and there was little room to negotiate, when it comes to AI’s, because we are going to be on them for 5-10 years, it’s important that we adjust and tweak as necessary so that we can have the best outcome for us, and that outcome and those decisions will look different for everyone!


Natural alternatives aromatase inhibitors

Yoga, swimming, walking on the beach are examples of activities that engage your joints without exerting them. It might seem silly that exercise is the only solace you can find to aid these side effects. But there is hope still, at least in the near future. Natural AIs are fast becoming a new area of research. For example, researchers have found that certain kinds of tea extracts have shown to inhibit aromatase. There are also edible plants and fungi that can have the same effect. There are even some fun options like coffee, spicy food, beer, and wine! (Yes, I was pretty excited about this too!).


No part of this survivorship is easy. It is frustrating that the pharmaceutical good comes with some hardship and longer term side effects we must manage. However, communicate your pain, doubts, and fears to your peers, medical team and most importantly to yourself. There are always solutions out there and we can find them. And we will search till we find them!

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