Oh, sorry to know Dr Currie can't help at the mo, Ann. That is unfortunate.
Been doing a trawl this morning & there are a couple of papers here that might be of interest to anyone facing this very difficult situation. Ann, I'm sorry I haven't the expertise to interpret the fine detail, nor the time today to digest them fully, but have just scanned them & pulled out some extracts that seem pertinent, but please don't rely on this as it is not intended as a recommendation. Simply a bit more info that may or may not help with your dilemma. On the whole, I think what they have to say is reassuring, but I also feel this is a decision each woman who has undergone treatment for breast cancer can only make for herself.
Interestingly, the first paper mentions that placement (depth of insertion within the vagina) may influence how much gets into systemic circulation. You will need to read the detail in the paper, but it seems that shallower insertion may result in less systemic absorption. The research seems to have involved women with an intact uterus though & I believe, like me, you've said you've had hysterectomy, so whether not having an intact uterus may make a difference to our systemic absorption I don't know.
It also touches on what we were discussing about absorption diminishing over time as the condition of the vaginal mucosa improves in response to the local treatment.
Systemic estradiol levels with low-dose vaginal estrogenshttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC7050796/"Systemic estradiol absorption may be influenced by the placement of estradiol higher (as with an applicator) versus lower (as without an applicator) in the vagina . . . From this evidence, the authors recommended placing vaginal estrogens in the outer third of the vagina to reduce the risk of estradiol transport to the uterus. In addition, lower estradiol absorption was observed with softgel capsule vaginal inserts placed without an applicator (lower in the vagina) versus tablet vaginal insert of the same doses inserted with an applicator (higher in the vagina) in a head-to-head study. Taken together, these data support a difference in estradiol absorption depending on placement of an estrogen product in the vagina."
"Thickness of the vaginal wall due to response with estrogen treatment may affect systemic absorption of estradiol when estrogens are used locally in the vagina. Some studies that measured estradiol levels at different times after vaginal estrogen use showed that peak and/or average levels declined over time as vaginal wall thickness likely increased with treatment"
"Certainly, after longer-term vaginal estrogen treatment (12 weeks, 83 or 84 days, 52 weeks), levels of circulating estradiol were similar to those at baseline or with placebo"
"CONCLUSIONS
Our review of systemic absorption of estradiol with use of low-dose and ultralow-dose vaginal estrogen therapies found low to negligible amounts of circulating estradiol that may be influenced by product formulation and vaginal placement."
Systemic Effects of Vaginally Administered Estrogen Therapy: A Reviewhttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC4354766/Vaginal Estrogen and Breast Cancer
"For urogenital symptoms, the vaginal ring that provides 5-10 μg/day locally and results in no increased serum estradiol, even if an ultra-sensitive bio-assay is used, meets these requirements. If vaginal estradiol less than 25 μg twice weekly or vaginal estriol less than 0.5 mg twice weekly is administered, there is no associated increase in serum estrogen. Expert opinion suggests that oral and transdermal hormone therapy are currently contraindicated for at least some women with a diagnosis of breast cancer. However, vaginal estrogen may provide relief of vaginal symptoms without an increase in serum levels.
An exception to this situation, however, may exist in women taking aromatase inhibitors. A recent study reported that in women using aromatase inhibitors, baseline serum estradiol was less than 5 pmol/l (1.36 pg/ml). After 2 weeks use of Vagifem® vaginal estradiol tablets, serum levels reached a mean concentration of 72 pmol/l (19.6 pg/ml). This level fell to less than 35 pmol/l (9.5 pg/ml) at 4 weeks except for two women where the estradiol remained elevated. The authors concluded that Vagifem® may counteract estrogen suppression caused by aromatase inhibitors and should not be used with these agents."
I'm sorry there is so much to get to grips with & wish it were more straightforward for us all.
Wx