Thread by @DrAttai

so, going to jump into this convo but based on the responses, not sure it will be worth it as it doesn't seem there is much interest in discussion #bcsm #bccww

https://twitter.com/coffeemommy/status/1337502815510401026

A lot of the negative response is understandably due to the use of a med with a lot of side effects (tamoxifen) to reduce breast density instead of focusing on improving screening techniques for those with dense breasts 1/ #bcsm #bccww

A bit of background info: ~40-50% of those screened w/mammograms have dense breasts. That makes it harder to find cancers on the mammogram. Dense breasts are also *one* risk factor for breast cancer but not everyone w/dense breasts is considered "high risk" 2/ #bcsm #bccww

Mammograms do not perform well in dense breasts. So we may recommend supplemental screening w/ultrasound and/or MRI. All have the downside of false positives (false alarms). The more we look, the more we find, and not everything we find needs to be found. 3/ #bcsm #bccww

So if there was some way to lower breast density (besides just getting older - and some women still have dense breasts even after menopause) that may improve mammo detection of cancer (and *maybe* improve outcomes) 4/ #bcsm #bccww

Ok next bit of background info: tamoxifen, raloxifene and anastrozole are all approved for risk reduction in those who have a calculated lifetime risk of ≥3% @ASCO Guideline: ascopubs.org/doi/10.1200/JC… 5/ #bcsm #bccww

and USPSTF guideline on risk reduction: uspreventiveservicestaskforce.org/uspstf/recomme… 6/ #bcsm #bccww

and one more link for risk-reducing meds: drattai.com/risk-reducing-… 7/ #bcsm #bccww

a lot of women who are at high risk are still reluctant to take endocrine therapy for risk reduction due to potential for side effects. Very valid concern 8/ #bcsm #bccww

but an option could be "mini-tam" - 5 mg of tamoxifen (cancer treatment dose is 20mg). 3 years of low dose tam vs placebo was shown to reduce risk of invasive cancer in those w/ADH (atypical ductal hyperplasia) or DCIS ascopubs.org/doi/full/10.12… 9/ #bcsm #bccww

AND - this low dose of tamoxifen (5mg) was shown to have similar side effect profile to placebo - so very well tolerated over the 3 years drattai.com/low-dose-tamox… 10/ #bcsm #bccww

ok - so dense breast make it harder to find cancers and can contribute to increased risk. Low dose (5mg) tamoxifen can reduce risk and at least in one placebo-controlled study was well tolerated 11/ #bcsm #bccww

The SABCS abstract (more on that in a minute) used 2.5mg tamoxifen x 6 months and found that breast density was diminished by 15%, and in the category C/D (dense breasts), screening sensitivity was improved by 5% 12/ #bcsm #bccww

probability of having ≥2cm tumor at diagnosis reduced by 4% in those responded to tam with ≥20% reduction in density 13/ #bcsm #bccww

So is this interesting? Yes, of course! Is it blanket recommendation to take tam to reduce breast density? No, of course not! Benefits modest at best, and no real information at this point on *actual* outcomes. Again, dose was 2.5gm of tam x 6 months 14 / #bcsm #bccww

Another VERY important point - this (and many other SABCS presentations) is an abstract. Many meeting abstracts NEVER get published. Of those that do, the final results may look different than the abstract 15/ #bcsm #bccww

but if the full study is published, and the findings hold up, there are some patients that would be willing to take a very low dose of tam to reduce density and improve the performance of mammograms (we aren't getting better screening tools anytime soon) 16/ #bcsm #bccww

Med onc @DrLaurenNye made a similar point

https://twitter.com/DrLaurenNye/status/1337551241795297281?s=20

17/ #bcsm #bccww

So bottom line - ultra-low dose tam has the potential to reduce breast density. Side effects should be minimal (5mg was similar to placebo). If study findings hold up in peer-reviewed publication, then it's an option to discuss w/patients 18/ #bcsm #bccww

We have imperfect screening. We have imperfect risk reduction. I was happy to see more study with very low dose tam as it seems to be well tolerated. Doesn't mean it's for everyone. And wouldn't change practice based on an abstract. 19/19 #bcsm #bccww