Taking AIs Beyond 5 Years

Last Modified: July 30, 2010

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Dear OncoLink "Ask The Experts,"

After bilateral mastectomies had chemo and radiation and then 3 years of Tamoxifen and will complete 5 years of Armidex in April. My oncologist says he will take me off Arimidex at that time although I am doing well on it and desire to continue taking it. Have you had any experience with women taking an aromatase inhibitor past the 5 years recommendation at this time? Are there ongoing clinical trials regarding this? Certainly other women must have the same concerns.


Kevin R. Fox, MD, Assistant Director, Clinical Affairs and Associate Professor of Hematology/Oncology at the Abramson Cancer Center of the University of Pennsylvania, responds:

We do not recommend extending arimidex beyond five years. We have no information on safety or efficacy of the drug after five years- and there are known risks to AIs. Clinical trials regarding longer durations of therapy have been done and we are awaiting these results (an extension of the MA17 study). In the meantime, we recommend discontinuation after five years.

Women who take drug for 5 years have lower recurrence risk 15 years after starting treatment

Mar 24, 2011 - Women with breast cancer who take tamoxifen for five years appear to have a lower risk of recurrence or contralateral breast cancer 15 years after starting treatment as compared to women who take the drug for two years, and they may also have a lower risk of cardiovascular disease and death from a cardiovascular event, according to a study published online March 21 in the Journal of Clinical Oncology.

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