Estradiol vs Estring - dosage and incontinence question

Hi Jannie1,

Welcome to the Online Community here at Macmillan. I’m Kirstine, one of the information nurses here in the Ask an Nurse channel. I can see you’ve joined our Breast Cancer Forum - I hope that’s been a warm and welcoming place to get support too.

I’m sorry to hear that you have been experiencing difficulty with urinary incontinence since starting anastrazole and then switching to tamoxifen. These genitourinary symptoms can be incredibly common when oestrogen is depleted, either because of menopause or from taking aromatase inhibitors (such as anastrazole) or selective oestrogen receptor modulators [SERM’s] (such as tamoxifen) as part of your cancer follow up treatment. It’s often caused by the tissues in the vagina and urinary tract becoming thinner. Topical oestrogen is a very low dose of hormone replacement therapy (HRT), applied directly to the tissue in the vagina in the form of creams or pessaries. It can be very effective to help reduce the cause of the problem and keep those tissues healthy, thus reducing urinary incontinence or discomfort.

You describe two products that your doctor has prescribed for you that are taken in different ways. The first, Estradiol 10mcg, is a small tablet used vaginally, often intermittently a few days per week or as prescribed by your doctor. The second, Estring 7.5mcg/24hours, is a type of ring pessary that can stay in place in the vaginal canal for up to 90 days releasing a steady dose across that time before it needs to be replaced.

It's easy to get units of measurements mixed up. Micrograms (mcg) are a unit that are one thousand times smaller than milligrams (mg), but they do look very similar when written down. My understanding of your dosage would be that when you took Estradiol 10mcg 3 or 4 times per week you might have been exposed to 30 or 40 micrograms (mcg) of the oestrogen replacement each week. With the Estring 7.5mcg/ 24 hours, that totals 52.5 micrograms (mcg) per week which is a higher dose than before. Although the silicone ring contains almost 2mg of oestrogen, the important factor is the rate that is released each day which is the 7.5mcg.

However, you describe that after 6 weeks, approximately 45 days into the 90-day regimen, you notice the symptoms coming back. You should certainly go back to your GP to discuss this as they can check to make sure nothing else is going on, such as a urinary tract infection (UTI), and can review your dosage or pessary type. It may be the case that your dose needs adjusted, or you may benefit from something else instead. You may find this article helpful as it describes the various options that you and your doctor can talk over together to find the best option for you.

I hope this is helpful, but it may also be an idea to talk with a Boots Macmillan Information Pharmacist, as they have the best experience to clarify and explain dosing information for medicines.

Best wishes,

Kirstine – Macmillan

Cancer Information Nurse Specialist

You can also speak with the Macmillan Support Line team of experts. Phone free on 0808 808 0000 (7 days a week, 8am-8pm) or send us an email. Ref KDf/ KS