Letrozole

cm2020

I am scheduled to start it this weekend. I am reading the thread on people overall doing well on AI's. But I am worried. Mainly about increased cholesterol and hair thinning and weight gain.

I wish I didn't have to take this med but I know I need to. I was scheduled to take Tamoxifen but it is contraindicated with Plaquenil which I take for chronic hives. It seems there are many more side effects and bad things that can happen with Letrozole.

I am not sure what I am looking for by posting, but I am just very nervous.

SarahSmilesatMe

Hello cm2020 - I may not be much help, but I’ll share... I started Letrozole on March 7th; little over a month ago. My side effects have been manageable. I don’t sleep as well (so I sleep later!), my joints are more stiff, so I try to walk every day (and that really helps). I wouldn’t say I have hot flashes, but I get hot easily. My most annoying side effect is that my hands fall asleep / tingle during the night or if I’m reading (not using them). Since this didn’t happen before the Letrozole, I presume it’s a side effect. I tell myself these are small things for the opportunity to add weeks, months, years to my life.

I think the quarantine is making me gain more weight than the Letrozole. I had high cholesterol before I started this med. My Primary care and I decided we would wait a bit to assess my reaction to the Letrozole before discussing a statin. I embrace this drug; because at this point, it’s the best for me. I hope this helps you to feel more comfortable!

Beesie

Tamoxifen and the AIs are different but one is not worse than the other - they are just different. Therefore they come with a different set of risks and side effects. Personally I find the list of serious risks from the AIs to be much less scary than the list of serious risks from Tamoxifen, but that's just my opinion.

Here's a comparison of side effects, from the BCO information pages. Letrozole is the genetic name Femara. I don't think this list is complete - the AIs can cause hair thinning and that's not included on the list - but it is pretty accurate.

The following article isn't exactly relevant to your situation because it is talking about the use of AIs versus Tamoxifen for the prevention of breast cancer. But there is a good explanation of the differences between the meds, which you might find helpful:

Aromatase Inhibitors in the Prevention of Breast Cancer. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC44640...

And this study showed that AIs are more effective at reducing the risk of metastatic recurrence, which certainly is a big "plus" in the AI/Letrozole column:

A comparison of letrozole and tamoxifen in postmenopausal women with early breast cancer. https://www.ncbi.nlm.nih.gov/pubmed/16382061

My advice... don't think the worst. Many women experience few side effects and find AIs to be very manageable - you might be one of those women. So start taking Letrozole thinking positive, knowing that it is reducing your risk of recurrence. Good luck!

cm2020

SarahSmilesatMe Your experience is very helpful. Thank you so much for letting me know. I haven't had a lipid panel in just over 2 years. My primary is worthless and I refuse to go to her again. My plan had been to get a new primary, but then the pandemic happened, cancer happened, and I haven't changed yet. I am considering asking my oncologist to order it and having it drawn in her office. At least I would have a baseline and something to take to a new primary when I can make that appointment (i need a physical too). My specialists are all so wonderful, I wish I could get that lucky with a primary dr!

Beesie This has been SO helpful! Thank you very very much! You are right, overthinking it isn't helpful, be informed, hope for the best, and know this is what I need to do to keep this type of cancer at bay. I will start taking it in the morning (my husband is picking it up for me tonight) and be grateful it exists.

cm2020

Beesie It does seem like the other 2 AIs have less side effects. Man I wish I had seen this chart prior to my dr prescribing Letrozole, I would have requested one of the other ones. I am not sure how she arrived at this particular one. At least there are 2 other options.

JLBinPDX

Hi cm202. I, too, wondered why my oncologist chose Letrozole over the other two. I had not seen this chart either and yes, it does seem the other two have fewer side effects. It makes me wonder if this is the only chart available. I love my onc so there has to be a specific reason he chose this over the other two. I've been on Letrozole for about three weeks and seems fairly okay. I started with some nausea but now take it at lunch so I have enough in my stomach and that seems to have gone. I've gained weight but hard to say if it's being inside and shirking my good eating and exercise or Letrozole (or both). I do wonder why a doc chooses one over another.

cm2020

JLBinPDX Have you found it affecting your sleep? I haven't slept for the past 2 nights (since I started it). It didn't occur to me until today that possibly it was the med. But I take it first thing in the morning, so it shouldn't affect my sleep. I'm glad you are doing okay on it. I plan on asking my oncologist why she chose it when the side effects seem more and more severe than the other 2. Should you ask you onc. will you follow up and let me know what he said? I also made an appointment with a different primary dr (it is also a different practice), and I am so relieved to hopefully finally be getting a decent primary. I will be talking to him about this med and also asking for some blood work to start monitoring thing (esp cholesterol). I am just going to see what my weight, blood work, and general tolerance of the med do before I make any decisions about asking to switch meds. For now, I hope for the best.

Edit: i had a thought.......i wonder if pharmaceutical reps have anything to do with how oncologists choose one med over another? that is a very very sobering and not good thought.

Beesie

cm2020, to be honest, I don't think the BCO chart includes all the side effects, so I don't know that it's fair to conclude that the other AIs have fewer side effects than Letrozole. I posted the BCO chart because at a high level it shows the differences between the AI side effects and the Tamoxifen side effects. It's also the only chart I can find that includes the 3 AIs and Tamoxifen. But there is more complete information available from other sources.

Here, from rxlist, are the side effects for Tamoxifen and each of the 3 AIs. Even these lists include a comment at the bottom that there may be other side effects not listed. It appears from these lists that there may be fewer side effects with Letrozole. Ultimately though it all comes down to how you react to the drug - each are well tolerated by some patients and not well tolerated by others. Until you try one, you won't know how you react.

Susi-Q

I started Letrozole on March 1 and have had some minor side effects. Most recently I have been super tired, particularly at mid day.

JLBinPDX

cm2020, thanks for writing back. I think I've decided that I'm going to stick with Letrozole. I'm very happy with my onc and he knows me well. He knows that I won't tolerate too many side effects before I abandon it all together. That tells me that he thinks it's the best fit (I, too, thought about the marketing/promo side of meds, but I just don't see that holding weight for him). I question the full accuracy of that initial chart as my onc knows weight is a concern for me (as for most) and I have a hard time believing the other two are as good as they show in that chart compared to Letrozole. I haven't had any change in sleep, although my sleep has always been more erratic and chopped up (meaning I wake up more) than prior to breast cancer. I'm sticking with it as it's been easier and better than I anticipated. I started WW yesterday (free through work) to lose maybe 10 pounds and then I'll be even better. Thanks, y'all.

cm2020

Beesie You are very kind to give me another list. I appreciate it. You are exactly right that until I have been on it, there is no way to predict the side effects. I am feeling a bit more positive because I have an appointment Monday with a new primary dr (and different practice). He has excellent reviews and I am hopeful that he will be good and we can work out a plan to keep an eye on things. The primary I have had for 2 years is truly horrible in every way (she has never actually even touched me and spends the entire visit sitting on her computer...i guarantee she has no idea what I look like) and I refuse to go back to her. But well, cancer. So now I need a good primary.

Susi-Q...Thank you for letting me know. I hope it improves over time and you don't have any other side effects.

JLBinPDX. Thank you for sharing your thoughts. I have only met my oncologist once so,of course, she doesn't know me at all. Your feelings are very encouraging and reassuring. I plan to stick with it too unless a reason comes up to change it. Hopefully we both do very well.

ThreeTree

CM- I don't know where I read it, and I don't have a link to post, but I seem to remember reading in more than one place (studies or reports of studies) that Letrozole seems to work slightly better than the other AI's, and that might be why some docs use it first. I have read so much about all of this that I can't remember where all of it was, nor do I save it all, but I'm almost certain that side by side Letrozole performs a bit better. I too have wondered about doctors' motivations and the influence of drug salespeople. Over the years, I have learned that sometimes about all a doctor knows about a drug is what he or she hears from drug sales reps.

I would give the Letrozole a try. I've been taking it every other day since mid January and though I'd rather not, I continue in spite of some annoying side effects - especially tiredness, being stiff as a board when I wake up, off and on back pain, lots of achy muscles and joints. I have been sleeping just fine and have only had minimal "warm spells" - not the severe hot flashes that some describe.

Best of luck if you try it.

cm2020

ThreeTree That is interesting that it may work a bit better. That would explain why my dr put me on it. Why do you take it only every other day? My dr told me to take it daily. Thank you for letting me know your side effects. It is good to know what may be coming. I do hope yours let up soon, they do not sound fun (though better than some of the really bad possibilities).

ThreeTree

Hi CM - I take it every other day, because I didn't want to start with the full dose, not knowing what to expect side effect wise. My doctor does not like that I take it every other day and wants me to take it every day, which so far, I'm not interested in doing. There is a thread under this hormone therapy topic called, "Half Dose of Femara". If you can find it, it might be real helpful for you. The thread was started years ago, but if you look at the later posts, of the last few months at least, you will see that many, including myself, have posted about the every other day dose option. Some on that thread and elsewhere on this site have said that their doctors told them every other day would be OK. Mine is not on board with that, but I also got a sense that she knows very little about it - again, just what a drug salesperson might say and/or only what the FDA recommends which is the every day dose of 2.5 mg..

In the "Half Dose of Femara" thread you can see that many have read research that suggests every other day is fine, and may be even more than enough. Some have posted links to the research. Novartis, the drug maker, even states in their own data that doses of .5 mg and above seem to suppress estrogen levels beyond detection in most cases. The standard prescribed dose is 2.5 mg per day - obviously a lot more than .5. I just made a personal choice that my doctor does not agree with, but others on here have said their doctors are OK with. It is not clear whether it makes a difference in side effects, though - largely because all of the doses suppress estrogen, and the side effects are due to the extremely low estrogen levels that occur with all those doses of .5 mg and above.

My doctor thinks I am short changing myself and getting only half the benefit, but everything I read on the internet and this site (a lot of which was posted/referenced by others on the thread mentioned) does not support that idea. Again, I would suggest that you find that thread (I think it is on about the second page of this Hormone Therapy topic list) and see if any of the information there is helpful to you.

In the end it will just boil down to a personal choice after researching and talking with your doctor. Isn't this awful, not having real clear cut info or choices?

JLBinPDX

I have read through that thread, ThreeTree. What I wonder is if you haven't taken a full dose for a week, two weeks, or more, you haven't given it a chance to know if you might, perhaps, not even have side effects. I can see stepping back. But after some slight initial nausea, I think I'm good with the full dose and I think no side effects (as I think I can chalk up some weight gain to do almost nothing and being inside). I, too, considered half dose as I've never taken medication in my life. But I couldn't see that there's enough research to show that it's as protective as full dose--perhaps I missed something, however. Of course, I appreciate that everyone makes his or her own decision, but the very little side effects that I, for one, experience could be your experience as well with full benefits. Just a thought.

cm2020

ThreeTree I appreciate your thoughts and the info to on the other thread. I'm glad you made a decision that you are comfortable with and at peace with. That is what is most important, that we each are comfortable and at peace with our decisions.

JLBinPDX I'm glad you also shared your thoughts on taking the med daily or every other day. Thank you. I have been, and will continue, to take it daily as my onc. prescribed. If the side effects become too much then I will talk to my onc and we will make a decision together about what to do at that point.

windingshores

he half life of letrozole is 2 days. The company insert says 0.5mg reduces estrogen below detectable levels. A dose of 2.5mg means 1.25mg left the next day, and .625 on the second day when, if you are alternating days, you would take your next dose. All of these levels are above the 0.5mg level cited as effective in the insert.

The thing is, reducing the dose logically would not reduce side effects because estrogen level is still below detectable level, and it is the low estrogen that causes side effects.

I took a full dose for almost 5 years. This past January I switched to alternating days to kind of taper down, and had MORE hot flashes. Who nows maybe the fluctuating levels caused that.

In early March I stopped altogether. I swear I felt better ON letrozole.

I wish people could feel less nervous about trying it, but I understand.

JLBinPDX

Really? Reducing the dose to half would not reduce the side effects? This is complicated, isn't it.

ThreeTree

Winding Shores - Sorry to hear that you are not feeling better after stopping. Hopefully time will help. I've read that it can take a good two months or more to get back to normal after the AI.

I just had a phone appointment with my oncologist a few hours ago and and she again implored me to take it every day instead of every other. I tried to explain essentially what you noted in your post above, but she would hear none of it. She kept saying something about how estrogen levels fluctuate throughout the day and that an every other day dose would not allow blood levels to reach steady state. She said something about needing 4 half lives before steady state can be reached. She did not cite any data for her comments. I told her I thought one of the problems with all of this was that there is so much we don't know, and that a lot of this data strongly suggests that every other day is fine. She got a little "huffy" and said basically that I was wrong and that there is much we do know, and that one thing we know is that the daily 2.5 mg suppresses estrogen in an effective manner. She told me that "no physician" would ever suggest that an every other day dose would be OK. I couldn't help but think about what you had said on the other thread about your doctor saying every other day would be OK (others on this site have said similar things too), but I did not bring that up with her. It is always a dead end when she and I talk about this. If I ever mention anything I have read on this site or the internet in general she says, "You can find anything on the internet", and dismisses most all of it out of hand. I've spent the rest of the day stressing and fretting about it all; wondering if I am just being really stupid or obstinate or something without really realizing it. Intellectually I still continue to see how the every other day would work - pretty much as you described, and I have also read, from the research.

Well, again I do hope you are feeling better soon. I think I saw something about the first 30 days being off of an AI as a time of some trouble, so wishing very much that with time, you will feel like your old self again. I sure appreciate your input on this site!

cm2020 - Glad you came to a decision that you are comfortable with.

JL - Thanks for your input. Yes, it is the low estrogen levels that cause the side effects and since all of these doses from .5mg to 2.5 mg apparently lower estrogen to undetectable levels, you still experience all of the negative side effects that come with estrogen suppression.

ThreeTree

Here is a link to one of the studies about alternative day dosing, if anyone is interested.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4740217/

JL - This is the one where they mention that there is no difference in side effects with the different doses.

ThreeTree

This is a monograph from Novartis, done in 2017 to update original info from late 1990's, if I remember correctly. In subsection 12-2 they discuss how doses of .5 mg and above suppress estrogen to undetectable levels. This might be the same as the package insert that Windingshores mentioned before. Interestingly, though, after updating all of the info, they said that they saw no reason to change there recommendation of a standard dose of 2.5 mg per day.

https://www.novartis.us/sites/www.novartis.us/files/Femara.pdf?campaign=FEM-900797&site=google&source=01030

JLBinPDX

I guess that's the part that I don't really get. I assumed people were considering or doing only half dose to lessen the side effects. If not for that reason, then what is the point? I feel like I'm missing something.

ThreeTree

This is a link to an abstract that again suggests that an every other day dose might well be sufficient - particularly for older people, who might not clear the drug from their system as rapidly as younger people.

https://cancerres.aacrjournals.org/content/75/9_Supplement/P1-12-15

ThreeTree

JL - I have read on this site where some say that when they take a break, or only take it every other day, or only take half a pill (1.25 mg) every day, they feel better than when they took the full 2.5 mg. every day. It's just subjective and anecdotal, but some do seem to feel that their side effects are lessened with the smaller doses. The research just didn't confirm that.

Also, one of the reasons I would prefer to go with every other day is that your liver and kidneys have to process all of these drugs, and to me, the less the better. Regardless of side effects, if I can get the same level of estrogen suppression with an every other day dose, it seems to be that my liver and kidneys will only have to process 50% of what they would if I took the full daily dose.

Additionally, a lot of dyes and fillers are toxic and even wind up being carcinogenic in and of themselves sometimes, so again, I would just prefer to put less of all this stuff in my body, if I can.

JLBinPDX

Okay, that helps me understand a little more. I've never been on meds, ever, so I get everything you're saying. I'm sticking with the full dose but will put all of this in the back of my mind if I happen to need it at some point. Best to you. Keep researching, if there's more out there, and make the best choice for you. You're, truly, the only one that has the final say.

windingshores

ThreeTree I think you misunderstood both my points. Sorry if I was unclear.

I did not feel horrible on letrozole. I do not need to feel better. However, going off does seem to involve some withdrawal effects, most likely from hormone levels wobbling a bit.

Secondly, I was trying to say that people might as well take the full dose. When I alternated days as I was tapering off, I experienced those fluctuations. Many more hot flashes, for one thing. I think achieving a steady state with the full dose every day is important. This is both in theory and from my own direct experience.

The fact that the drug insert says 0.5mg effectively suppresses estrogen might be interpreted to mean that alternating would be okay, given the half life. However, 1) that should not reduce side effects unless the lower dose actually DOES NOT suppress estrogen and 2) fluctuating levels of the drug seems to cause more problems than a steady state, even if the steady state means the full dose every day

ThreeTree

Windingshores - Sorry, glad you clarified your points.