Tamoxifen for lobular in pre menopausal women?

9lives70, I have copied a post here that I made on the ILC Symposium thread, because it is kind of buried there. Your question does not have a definitive answer, which is extremely frustrating, I know. I think I would ask if they can do any test to determine luminal A vs. luminal B for you, or a test (Mammaprint?) to corroborate the low Oncotype. Discuss whether there are any other details of your case that might hint at whether this would likely be a well-behaved ILC or not. Did your pathology report show a Ki67 numberr?

Tamoxifen for ILC -- ILC Symposium 2016, Report from ShetlandPony

(This post is based on notes I took at the symposium, and reflects my own understanding. Please consult the literature and your own experts to verify and apply.)

Tamoxifen and Premenopausal ILC:

It seemed to be generally acknowledged by the physicians and researchers that the question of whether tamoxifen is effective for ILC is worth looking into. Opinions of the medical oncologists varied. I heard from two doctors who simply do not prescribe tamoxifen for their ILC patients, even low-risk ones. One makes an exception for a young patient who wishes to have children in the future. I also heard from doctors who believe that the current evidence is insufficient for them to change practice, and they continue to recommend tamoxifen for lower-risk premenopausal patients. They think the sample size for current data is too small, and are reluctant to subject their premenopausal patients to ovarian suppression or removal, and to the side effects of aromatase inhibitors, without stronger evidence. It is hoped that a sub-analysis of the ILC patients from the SOFT and TEXT trials will shed some light. (SOFT already indicates that ovarian suppression/ablation plus an aromatase inhibitor had the best outcome for the premenopausal patients whose cancer was high-risk enough to require chemo or who were under age 35.) Interestingly, the MOs I met who avoid tamoxifen for ILC are from Europe/UK, while the pro-tamoxifen MOs are from the USA. It seems to me that recommending a treatment not strictly in line with what has been standard practice in the USA is something they are not willing to do. I think they may wait to see if future NCCN guidelines explicitly address tamoxifen and premenopausal ILC.

Tamoxifen and Postmenopausal ILC – My notes from M. Knauer of Kantonsspital, Switzerland:

A 2015 analysis from the ABCSG-8 trial looked at disease-free survival and overall survival in postmenopausal women on tamoxifen vs. anastrozole (the aromatase inhibitor Arimidex). Luminal A and Luminal B ILC subtypes were defined by the PAM50 multi-gene profile. (Dr. Knauer also mentioned a Ki67 cutoff of 14% for Luminal A vs. Luminal B. I think maybe this is a way of assigning subtype without the PAM50.) He said that 19% of ILC is Luminal B.

For Luminal A ILC, there was no difference in DFS or OS with anastrozole vs. tamoxifen.

For Luminal B ILC, there was better DFS and OS with anastrozole.

Dr. Knauer believes the PAM50 is predictive and can be used for treatment decisions. Note that one or two researchers/physicians present spoke their objection that the ILC cohort in this study was not large enough to allow for conclusions to be drawn.

Shetlandpony, thank you for posting the ilc symposium 2016 info. I had been looking for that.

I had ilc and idc with lobular features and 95% er and less than 1% pr, so like luminal B. I did 2.5 years on anastrozole but had to switch to exemestane. Now I am done, I hope.

I'm on zoladex and Tamoxifen. My oncologist doesn't like to give an AI to anyone who is not definitely menopausal, and she is not convinced ovarian suppression guarantees menopause.

BUT she is keen for me to get my ovaries removed so that she can move me on to an AI.

This is based on the SOFT trial.

For those who are pre-menopausal and would like to read about Ovarian Suppression (plus tamoxifen or an AI) and to consult SOFT and TEXT/SOFT study publications to further inform discussions with their medical oncologist, I have the following bookmarked.

This is NOT a comprehensive list of publications related to the SOFT and TEXT trials.

These documents are not a substitute for current, case-specific, expert professional medical advice from a Medical Oncologist ("MO"). It is easy to misunderstand such highly technical documents and whether and how their guidance should be applied in the individual case. Guidelines represent snapshots in time, and there may be appropriate exceptions to what is provided for the general case. In addition, there may be additional, more recent studies and/or conflicting studies. Therefore, if a document influences your thinking in any way, it is essential to confirm your understanding, as well as currency and applicability to your case, with your MO.

ASCO 2016 Guideline Update re Ovarian Suppression:

Burstein (2016), "Adjuvant Endocrine Therapy for Women With Hormone Receptor–Positive Breast Cancer: American Society of Clinical Oncology Clinical Practice Guideline Update on Ovarian Suppression"

http://ascopubs.org/doi/pdf/10.1200/JCO.2015.65.9573

(Free PDF version available for download; See also, Supplements tab)

The above Guideline Update was issued in light of the following study publications:

SOFT: Francis (2015), "Adjuvant Ovarian Suppression in Premenopausal Breast Cancer"

"[R]esults of the planned primary analysis in SOFT comparing adjuvant tamoxifen plus ovarian suppression with tamoxifen alone after a median follow-up of 67 months"

Main Page: http://www.nejm.org/doi/full/10.1056/nejmoa1412379#t=article

PDF version: http://www.nejm.org/doi/pdf/10.1056/NEJMoa1412379

Supplementary Appendix to Francis: http://www.nejm.org/doi/suppl/10.1056/NEJMoa1412379/suppl_file/nejmoa1412379_appendix.pdf

TEXT/SOFT: Pagani (2014), "Adjuvant Exemestane with Ovarian Suppression in Premenopausal Breast Cancer"

"[P]rimary combined analysis of data from TEXT and SOFT comparing adjuvant exemestane plus ovarian suppression with adjuvant tamoxifen plus ovarian suppression after a median follow-up of 68 months"

Main Page: http://www.nejm.org/doi/full/10.1056/nejmoa1404037#t=article

PDF version: http://www.nejm.org/doi/pdf/10.1056/NEJMoa1404037

Supplementary Appendix to Pagani: http://www.nejm.org/doi/suppl/10.1056/NEJMoa1404037/suppl_file/nejmoa1404037_appendix.pdf

[[[EDIT: Since the above results and Guideline Update were published, additional results are now available:

SOFT/TEXT: Francis et al. (2018), "Tailoring Adjuvant Endocrine Therapy for Premenopausal Breast Cancer"

Main Page: https://www.nejm.org/doi/full/10.1056/NEJMoa1803164

PDF version: https://www.nejm.org/doi/pdf/10.1056/NEJMoa1803164

Supplementary Appendix to Francis (2018): https://www.nejm.org/doi/suppl/10.1056/NEJMoa1803164/suppl_file/nejmoa1803164_appendix.pdf ]]]

Hi 9lives70:

I have some education and experience in the biology area, but no medical training or experience whatsoever.

BarredOwl

labgirl, can I ask where you are being treated and why you were given the metabolizing and breast cancer index tests? I am also in COlorado and have very similar diagnosis--low oncotype score, LCIS, IDC, ILC. I am also premenopausal (48)and currently on Tamoxifen.

I haven't updated my profile for the ILC, LCIS or Tamoxifen as this came after final path report from surgery.

9lives70, I think the CYP2D6 test is somewhat controversial (I had that test done but the results were inconclusive so we had the endoxifen levels tested instead). And I think the endoxifen testing isn't done much and isn't definitive but I've read a lot of studies and there does appear to be some correlation between menopausal side effects or lack thereof and endoxifen levels. And also there have been some studies done on endoxifen levels and recurrence such that there appears to be an acceptable threshold level among some researchers. Since there is no real alternative for premenopausal women aside from suppression or oophorectomy I don't think there is a lot of interest in looking at tamoxifen and whether to increase dosage. My purpose in doing all of these tests is to get as much information as I can even though there will still be unknowns (I guess that's how I work). I have been lucky to have a dr who has been supportive. But sometimes too much information just gets confusing! The big problem I think is tamoxifen resistance or ineffectiveness especially with ILC, related to your original topic. Ultimately I will shut down the estrogen probably in the next year or two. I'll report back about what I hear from Cleveland Clinic

Dx at age 43, had been on Tamoxifen for 5 years, and Zoladex injection for 3.5hrs. Don't know whether it works but I am a worrier, it made me feel better.