Can Anti-Estrogen Therapy Help Deter Breast Cancer Recurrence Beyond Five Years?

Recent breast cancer studies revealed the value and appropriateness of extending anti-estrogen therapy for longer durations in breast cancer survivors with early stage ER+ breast cancer. Currently, these patients are routinely put on at least a five-year course of anti-estrogen therapy to reduce the risk of breast cancer recurrence. The uncertainty arises at the critical five-year mark when doctors and patients must evaluate the decision to end therapy or continue for another five years. I spoke with Dr. Tara Sanft, Yale Cancer Center Survivorship Clinic Medical Director of Adult Survivorship to learn about how women can learn more about the active roles they can take in charting the course of their treatment journey.


Lisa LaGrou Oakland County Moms – Why has the anti-estrogen therapy for breast cancer survivors routinely been a five-year plan?

Dr. Tara Sanft – Well, we’ve done many successive studies that have shown that five years reduces the risk of recurrence. We’ve had study results that show that five years is better than two years or one year and so five years has become the norm. But, because 50% of recurrences happen after the five-year mark, we, as an oncology community, have had the question “Should we be treating patients longer?” Some data from San Antonio has helped us understand that better this year.

Lisa LaGrou Oakland County Moms – What does that current research say about this traditional five-year benchmark?

Dr. Tara Sanft – Well, we learned the results of three large randomized trials that were released last week at San Antonio. And, what we found was that women who took therapy longer than five years compared to women who did not had a smaller, but not significant, benefit. So, what does this mean? What it really means is that we need to better understand which women out of all the breast cancer survivors are at the highest risk of that late recurennce after five years so that we might tailor our recommendations to target them. One way that we can do that is through the use of Genomic tools. One tool is called the breast cancer index test. This is a test of a cancer gene that looks at the risk of late recurrence after five years and also the likelihood that the cancer will respond to treatment with endocrine therapy after five years. So, it can help be a piece of the puzzle to women who are trying to decide whether or not they should continue on their therapy.

Lisa LaGrou Oakland County Moms – Yes, that kind of answers my next question of how a test like that would help women make decisions about their health and how to collaborate with her doctor on this treatment; and are there any risks to the estrogen therapy?

Dr. Tara Sanft – Yes, well that’s a great question. The truth is that these therapies have a host of side effects that continue throughout time that you’re taking it. The most common side effects include hot flashes, muscle aches and joint pain, and sexual dysfunction. So, if you’re taking a treatment for 10 years, this can really impact your quality of life. So, what tools like this can do is identify those women who really need it, and for everybody else, they can stop at the traditional five-year mark.

Lisa LaGrou Oakland County Moms – Where can we learn more?

Dr. Tara Sanft – I’ve partnered with Biotheranostics and they have a great website to get this information. People can go to

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