The Dark Side of Aromatase Inhibitors – Part 1

I divided this topic into a couple posts because I’m working on being less wordy and more concise in my writing. Part one will be my attempt to convey general information about aromatase inhibitors. Part 2 will be focused on my personal experience – rant, so stay tuned.

Update:  You might want to read and download, Endocrine Therapy – Managing & Making Decisions About Your Aromatase Inhibitor Medication.

Many breast cancer tumors are estrogen positive (ER-positive), progesterone positive (PR-positive), or both (ER-positive and PR-positive). Mine was both.

By the way, this information about your tumor(s) is provided in your pathology report. You should have a copy of this report so you can familiarize yourself with your unique cancer’s biology, even though this might sound like the last thing you want to do after your diagnosis.

Be sure to ask for a copy if you don’t/didn’t receive one.

If a woman is ER and/or PR positive, her oncologist might very likely prescribe an aromatase inhibitor after surgery, chemotherapy or radiation as part of her adjuvant therapy treatment plan. The intent is, of course, to prevent recurrence.

There are three kinds of aromatase inhibitors (referred to as ‘AIs’ from here on out) that have been FDA approved:  anastrozole (Arimidex®), letrozole (Femera®) and exemestane (Aromasin®).

Basically, these drugs block tumor growth by lowering the body’s natural supply of estrogen.

How do they do this?

These drugs don’t allow the food supply (estrogen) to get to the tumor because they block the aromatase enzyme, which is needed for the production of estrogen.

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Hence the name, aromatase inhibitors.

AIs are often prescribed for post-menopausal women because they don’t block estrogen produced by the ovaries, but do inhibit estrogen production in other body tissues. If you’re not post-menopausal, the benefit’s not there. For pre-menopausal women with estrogen positive cancers, Tamoxifen is still the recommended hormonal adjuvant therapy drug most often prescribed.

Before cancer, I didn’t even know that in addition to the ovaries other body tissues also produce estrogen, but they do.

As I understand it, there isn’t a lot of difference between the three AI drugs. One difference however, is that Aromasin® is an irreversible aromatase inhibitor (stops aromatase enzyme’s production process permanently) while the other two are not.

Studies seem to indicate the effectiveness of the drugs in preventing recurrence is pretty much the same.

AIs have become standard treatment for adjuvant hormonal therapy for many post-menopausal breast cancer patients. You gotta shut that estrogen production line down, and that’s what AIs do.

I remember the day when oncologist number one showed Dear Hubby and me all those mind-boggling, ten-year survival odds charts. The charts indicated if I agreed to add Arimidex® as part of my adjuvant treatment plan, I would gain another six percentage points for my staying-alive plan.

I was on board. I wanted those additional six percentage points on my side.

Who wouldn’t?

And now on to the dark side of AIs — in case you can’t guess — but I’m betting you probably can, this would be the nasty side effects.

Every person is different. Just because you’ve heard horror stories about unpleasant side effects, don’t assume you’ll experience the same.

Having said this, some of the side effects are fairly common and even somewhat predictable.

Generally speaking and maybe even mildly comforting to know (then again, maybe not), the side effects of all three AIs are similar.

The most-often mentioned side effects are:  joint pain, bone loss, bone fractures, lowered libido, hair loss/thinning, weight gain, hot flashes and sleep issues to name a few. (Yikes, do we really need more?)

The side effects are often not addressed adequately, if at all, by oncologists. This is too bad because side effects can, at the lesser end of the spectrum, be highly annoying and at the worst end, be extremely debilitating.

I speak from experience on this as I have had some very unsettling side effects myself.

In fact, side effects (mine anyway) are the focus of The Dark Side of Aromatase Inhibitors – Part 2.

Get your rants ready too!

Note:  Please remember that while I always strive for accuracy in facts I share, my posts also generally include my thoughts and opinions and are not intended to be medical advice specific to you. Please discuss all concerns with your doctor.

Are you on an aromatase inhibitor or do you know someone who is?

Are you on Tamoxifen?

If so, how are things going and are the side effect issues (if you have any) being adequately addressed?

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Update:  You might want to read and download, Endocrine Therapy – Managing & Making Decisions About Your Aromatase Inhibitor Medication.