Ribociclib

Ribociclib 400 mg – has anyone reduced to 200 mg because of side effects?

Going through breast cancer treatment

Hormone therapy

Hello everyone,

I joined this forum when I started taking Ribociclib in December last year. Because of brain fog and very low energy, I haven’t been back since and have found it difficult to navigate the forum. I’m hoping to reconnect and hear about other people’s experiences.

I’ve been reading some of your posts today, and it’s reassuring to know I’m not alone in dealing with some of these side effects.

I’m now 66, and I was diagnosed with breast cancer in April 2024, just few months before I was 65. I had a right breast invasive ductal carcinoma (IDC), which was Grade 2, oestrogen receptor-positive (ER 8), progesterone receptor-positive (PR 7) and HER2-negative. The cancer had spread to one of my lymph nodes. I had two operations to remove the lump (the second was to achieve clear margins), followed by five weeks of radiotherapy.

The pathology showed a 13.5 mm invasive tumour, with a composite tumour size of 19 mm including DCIS. There was also lymphovascular invasion (LVI), and 1 of the 6 lymph nodes removed was positive, with a 3.5 mm deposit. My second operation achieved a clear margin.

I also had an Oncotype DX test carried out on my tumour tissue. My recurrence score was 16, with a reported 5-year distant recurrence risk of 4%. My understanding is that, because the score was relatively low, my oncologist felt that chemotherapy was unlikely to provide enough additional benefit, so I didn’t have chemotherapy. My staging CT also showed no evidence of distant metastatic disease.

Although I had a full hysterectomy around 14 years ago and had already been through the menopause, my cancer was still hormone-positive, which came as a surprise to me.

Alongside the cancer, I have a long history of other health problems, including unexplained infertility, more than 35 years of chronic fatigue, over 20 years of insomnia, memory problems (especially short term memory), a chronic dry cough, and lower back pain caused by a degenerated facet joint. The back pain is particularly debilitating, as I struggle to sit for more than 15 minutes or lie down for more than a few hours. Unfortunately, I’ve tried almost every available treatment without much success.

After radiotherapy, I started taking Anastrozole. I also had a bone density scan, which showed that I already had osteoporosis in my lower back, so I was started on a weekly Alendronic acid tablet.

Last September, my oncologist contacted me to say that Ribociclib had been approved as an additional preventative treatment for my type of breast cancer. I was advised that it could have significant side effects, but that I needed to start it by December if I wanted the opportunity to take it. I decided it was worth trying, knowing that I could stop if I couldn’t tolerate it.

So far, my blood tests, including my liver and kidney function, have all been fine. However, the fatigue has become overwhelming. I also have a persistently high heart rate, my chronic dry cough seems worse, and for the past three months I’ve had very watery eyes.

My breast cancer nurse said that if the side effects become too difficult, my Ribociclib dose could be reduced from 400 mg to 200 mg.

My biggest concern is whether the lower dose would still be effective at reducing the risk of my cancer returning. I also wonder whether changing from Anastrozole to another hormone therapy might help, or whether the Ribociclib is more likely to be causing these symptoms.

I’d really appreciate hearing from anyone who has reduced their Ribociclib dose, changed hormone therapy, or experienced similar side effects.

Did reducing the dose help with the fatigue? What did your oncologist tell you about the effectiveness of the lower dose? Has anyone changed from Anastrozole to another hormone therapy and found that their side effects improved?

I’d also be very interested to hear from anyone with a similar diagnosis and treatment plan, particularly those who have had one positive lymph node and a relatively low Oncotype DX score.

I hope I’ve posted this in the right section. Apologies if there is already a similar thread elsewhere—I found a few discussions about Ribociclib, but I wasn’t sure where best to post my questions.

Thank you for taking the time to read my post. Any advice or shared experiences would be greatly appreciated.

Best wishes,