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Discontinuing Tamoxifen Too Early Raises Women’s Risk of Death

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Study results show adherence to 5-year treatment is crucial

Recent study findings show that women with breast cancer who discontinue their prescribed tamoxifen or aromatase inhibitors too early following initial treatment increase their chance of cancer recurrence and risk of dying.

For the study, Dr Colin McCowan of the University of Glasgow, and his colleagues from the University of Dundee, reviewed the prescription records of 3361 women in Scotland. The women were prescribed either tamoxifen (2849 women) or an aromatase inhibitor (512 women) for 5 years following their initial treatment. To determine adherence, the researchers calculated whether the women diligently followed the once-daily pill routine and for how long.

McCowan and colleagues found that women collected 90% of their tablets, on average, during the first year of treatment. However, during subsequent years the percentage decreased to 82%, 77%, and 59%, respectively. The trend continued during the fifth year, when only half of the women collected 51% or less of their prescription.

Furthermore, when compared with women who took more than 80% of the prescription during each of the 5 years, women who followed the course of therapy for up to 3 years but then took fewer than 80% of their pills in the fourth and fifth years experienced a higher risk of cancer recurrence and death from breast cancer.

“This study shows us that it’s vitally important that breast cancer patients…follow their prescribed treatment regimes on a daily basis for the full 5-year period,” McCowan said.

The study is published in British Journal of Cancer.

Source: University of Dundee.