For many years, women with ER positive breast cancers have been given endocrine/anti-estrogen therapy as part of their treatment. Sometimes this comes after planned chemotherapy and sometimes it is in lieu of chemotherapy and begins after surgery or after surgery and radiation. For a number of those years, everyone was given Tamoxifen which had demonstrated real value in reduction of recurrence risk. Beginning in the late 1990s or early 2000s, post-menopausal women were prescribed one of the three aromatase inhibitors (AIs). Some women had two and a half years of tamoxifen and were then switched, and some women started right out with one of the AIs. Research continued, and the general trend has been to extend the total duration of endocrine therapy.

  Since approximately half of all recurrences for women with ER positive breast cancers happen after five years of this therapy, it seems to make sense to prolong the treatment. I recently heard that the risk of recurrence for ER positive breast cancers does not truly drop until after twenty years. This is a very long time. There is a continuing conversation about all of this, and you may be interested in these conflicting views from ASCO Reading Room. If you just want the quick summary, it is this: Any medication comes with side effects, so the risks must always be balanced against the potential benefit. That ratio varies woman to woman, and most doctors now believe that there is not a single recommendation. For us, it comes down to Talk with your doctor and, together, make the best informed choice for your own care.

  Here is the start and a link to read more:

Debating whether All Patients with ER Positive Breast Cancers Should Have Extended Adjuvant Endocrine Therapy

Many Patients Remain at Risk for Distant Recurrence over the Long Term

by Wayne Kuznar

Debating Whether All Patients with ER-Positive Breast Cancer Should Have Extended