Rituxin and HRT (Hormone Replacement Therapy)

[Lisa-1959]

I have a question regarding a possible medication side effect. This is an odd one (and also embarrassing), but I have spoken with a pharmacist, my local oncologist's nurse, a nurse practioner at my local cancer center, a nurse with the drug company that makes Rituxin, and read multiple entries on the computer, and no one has ever heard of or reported this particular issue.

I started Venetoclax on January 21st, ramped up to 400 mg on February 18th, and had my first Rituxin infusion on February 25th. For the most part, everything went well on the Venetoclax (some joint stiffness and tummy distress), but I did breakout in hives during the Rituxin infusion...had to get additional Benadryl and steroids to settle down the allergic reaction. Then the strange thing happened...a couple of days after the first Rituxin infusion, both of my breasts swelled. They were visibly bigger, felt heavier than normal yet weight didn't change, both breasts were very sore like I was in full blown PMS mode, and undergarments fit differently.

I have 2 more infusions behind me, and my breasts are still enlarged compared to what they were prior to starting the Rituxin. My weight is now up about 5 pounds, but for the first month, I held in at 142 pounds. However, even with the weight gain, they are still larger and heavier than is normal for me.

The only "theory" I have heard that makes any sense is from the pharmacist in wondering whether the Rituxin (or possibly the Venetoclax/Rituxin cocktail) is interacting with the hormone replacement therapy I am on. I use Estradiol (transdermal patch) 0.0375 mg/day which is changed twice a week, and I have been using it ~15 years. At the recommendation of a nurse practitioner at my local cancer center, I actually have a PCP appointment tomorrow (May 16) to talk about weening myself off the HRT.

Has anyone ever heard of this happening while on Venetoclax or Rituxin? It has just been strange...feel like I am in PMS all over again! Ugh!

[Jm954 Administrator]

Lisa,

I'm sorry this has happened to you and no, I have never heard of this side effect before. I just wanted to say that I hope that uncomfortable feeling resolves soon for you.

Jackie

[Lisa-1959 in reply to Jm954]

Thanks...it isn't earth shattering but really weird. It may have nothing to do with the Rituxin, but the coincidence is too strange.

[AnnieZ102]

I had the same thing happen after my first treatment, but it only lasted for about a week. I'm on a different treatment protocol to you, but on the same HRT. I'm coming to the end of cycle 3 now and it hasn't recurred. Tbh it was a minor discomfort compared to what I was expecting!

Hope it eases off soon.

Anne

[Lisa-1959 in reply to AnnieZ102]

Wow...at least I am not crazy! I know when I called the manufacturer at the suggestion of the pharmacist, I could tell by the tone that the nurse thought my possible connection was a stretch. I tend to be pretty sensitive to meds, so maybe that is the bigger problem. Kept thinking my "issue" would go away, but so far it hasn't. I have my 4th Rituxin infusion on Monday.

[81ue]

I'm on venetoclax and had 4 rituxan infusions during my continued ramp up so I don't know which one is the culprit yet. I'm monitoring a strange soreness that isn't muscle soreness but if I touch the top areas of my chest and breast or between breasts it has that soreness to the touch/press. The soreness is also below my shoulder blade on the back edge down to top of ribs only. It reminds me a bit about breast puberty growing pain soreness (but I never had that kind of soreness in the back). It only hurts when I press the area. My bra does fit tighter but I don't visibly see it as bigger. My next rituxan is in 2 months. If the soreness persists then I'll blame venetoclax. The only other medications I'm on are allopurinol and protonix (I never thought to blame these two).

[Lisa-1959 in reply to 81ue]

Interesting...strange on the back soreness. Since I had been on Venetoclax 5 weeks with no issues except joint stiffness and some tummy distress, I have a hard time pointing to it being the cause of my swelling and soreness. Also, I had been on allopurinol for 2 months in the fall when I was on Ibrutinib...no problems there either. I do realize the combination of Venetoclax and Rituxin could be the issue, but since the problems surfaces a few days after my first infusion, the Rituxin seems likely. At least that is my convoluted logic!

Today my PCP decided I should discontinue the hormones and see if there was any connection. Like you with the next Rituxin, I guess time will tell! Good luck!

[81ue]

Best description of the soreness I found so far :"Static mechanical allodynia – triggered by light pressure" from healthrising.org/blog/2015/...

I'm still sore under the skin over breasts and chest, back of upper arms and sides of upper back, also hips, and still don't know what did it. It's not a muscle soreness, it's a surface soreness.

[Lisa-1959 in reply to 81ue]

My soreness has gone away, but I am still swollen. I don't think I have been off the hormones long enough to see any changes, so hopefully time will tell. Your situation is definitely strange. Hope it subsides!

[81ue in reply to Lisa-1959]

I'm wanting to point to rituximab as the culprit. The soreness and allodynia I had in the upper arms, back hips etc went away gradually after the initial 4 weeks infusions and hugs don't hurt anymore . I'm now on the every other month maintenance schedule for rituximab. After the rituximab maintenance infusion this month I have again noticed sore breasts (like a 'growing pains' kind of soreness). This time it isn't in my arms, back or hips. The next infusion will be in September. I'm going to pay attention to when the breast soreness leaves and how long that will take, then monitor again for if it sets in again on the rituximab maintenance day.

[Lisa-1959 in reply to 81ue]

Interesting! I have been off my hormones since mid-May, and the soreness went away fairly quickly after I stopped, but my breasts are still larger than they should be. I do agree that the Rituxin is the culprit. Unfortunately, dropping my hormones has activated the miserable hot flashes, but hopefully those will pass fairly soon!