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Debbie L. · 03-25-2015, 02:17 PM

In large groups of ERPR positive women, the benefit of endocrine therapy (AIs, Tamoxifen) is probably in the area of 30-50% relative reduction in recurrence. But as others have said, it's believed that the benefit may be higher for cancers that are highly ER+ and lower for those that are less ER+. Plus there's new information (and more to come) about the benefits of endocrine therapy continued beyond 5 years.

But that is only the relative risk reduction, and that has to be factored into your individual risk of recurrence (factoring in stage and other details of the cancer), to get the absolute benefit to you.

For example, if a woman completed treatment with a 50% chance of recurrence, and then did endocrine treatment that reduced her risk by 50%, she would be left with a 25% absolute risk of recurrence. Another woman with a 5% risk of recurrence after treatment would have that reduced to 2.5% with the same treatment. IOW, the higher your risk of recurrence is, the more absolute benefit you will gain from any treatment.

Your oncologist is the one to ask for these numbers. Again, they will have been garnered from large groups of women who may not be exactly matched to your individual cancer details, but they will be the closest we can get, and helpful in making treatment decisions.

Here's a quotation from a fairly-recent (12/2013) article regarding 5 years of Tamoxifen: "In the most recent Oxford overview of women with estrogen receptor (ER)-positive breast cancer, which included 15 years of follow-up, use of 5 years of adjuvant tamoxifen (compared with no therapy) resulted in a halving of recurrence rates during years 0 through 4, and a reduction by one-third in years 5 through 9." The article is actually discussing duration of therapy (and there is newer data also supporting longer therapy), but it has some useful information for your question:

Adjuvant Endocrine Therapy for Breast Cancer: How Long Is Long Enough?

But again, you should ask your oncologist to go over this with you. It could probably be done with a phone call.

Debbie Laxague

03-25-2015, 02:17 PM	#11
Debbie L. Senior Member Join Date: Jul 2006 Posts: 463	Re: effectiveness? In large groups of ERPR positive women, the benefit of endocrine therapy (AIs, Tamoxifen) is probably in the area of 30-50% relative reduction in recurrence. But as others have said, it's believed that the benefit may be higher for cancers that are highly ER+ and lower for those that are less ER+. Plus there's new information (and more to come) about the benefits of endocrine therapy continued beyond 5 years. But that is only the relative risk reduction, and that has to be factored into your individual risk of recurrence (factoring in stage and other details of the cancer), to get the absolute benefit to you. For example, if a woman completed treatment with a 50% chance of recurrence, and then did endocrine treatment that reduced her risk by 50%, she would be left with a 25% absolute risk of recurrence. Another woman with a 5% risk of recurrence after treatment would have that reduced to 2.5% with the same treatment. IOW, the higher your risk of recurrence is, the more absolute benefit you will gain from any treatment. Your oncologist is the one to ask for these numbers. Again, they will have been garnered from large groups of women who may not be exactly matched to your individual cancer details, but they will be the closest we can get, and helpful in making treatment decisions. Here's a quotation from a fairly-recent (12/2013) article regarding 5 years of Tamoxifen: "In the most recent Oxford overview of women with estrogen receptor (ER)-positive breast cancer, which included 15 years of follow-up, use of 5 years of adjuvant tamoxifen (compared with no therapy) resulted in a halving of recurrence rates during years 0 through 4, and a reduction by one-third in years 5 through 9." The article is actually discussing duration of therapy (and there is newer data also supporting longer therapy), but it has some useful information for your question: Adjuvant Endocrine Therapy for Breast Cancer: How Long Is Long Enough? But again, you should ask your oncologist to go over this with you. It could probably be done with a phone call. Debbie Laxague