A Third of Patients Abandon Breast Cancer Drug Due to Side Effects

Over a third of post-menopausal breast cancer patients who take aromatase inhibitors abandon their treatment, because the drug’s side effects are so unbearable, according to researchers from Northwestern University. Aromatase inhibitors are typically given to patients following chemotherapy, radiation therapy, and breast cancer surgery, usually for about 5 years.

Lead author, Professor Lynne Wagner and associates conducted a study involving 700 female patients who were on aromatase inhibitor regimens. After four years, 36% of them had fallen out of treatment because the side effects associated with the drug were so intolerable. One in every ten patients abandoned treatment within 24 months.

The extremely unpleasant side effects that prompted the women to stop their medication regimen included a drop in libido, weight gain, hot flashes, and severe joint pain. Those who had already undergone radiation therapy or chemotherapy were found to be more likely to stop taking the medication.

According to Wagner, “If they (patients) had a rough time with chemo, if they’re feeling beaten up by treatment and medications, or if they’re the type of person who has difficulty tolerating side effects, then they’re much more likely to quit the drugs early.”

The researchers also discovered that what doctors perceived as side effects associated with the drugs were very different when compared to how patients described their experiences. When previous studies asked doctors about side effects associated with aromatase inhibitors, they claimed only 5% of patients reported moderate to severe side effects. This data is in stark contrast to the 36% of patients who dropped out of treatment in this latest study.

Wagner adds, “Now we’re appreciating that there’s a significant gap between patient-reported symptoms and provider-reported symptoms. That gap widens when we’re talking about more subjective symptoms, things like pain or fatigue that only a patient can report.”

Patients often perceive themselves as being difficult and bothersome, often they will not report unbearable side effects to their doctors. Busy doctors with hectic schedules and full waiting rooms may not be giving enough time with patients to address this issue, the researchers suggested.

Aromatase inhibitors are drugs often used to treat breast and ovarian cancer in postmenopausal patients. Ovarian and breast cancers require estrogen to grow. The enzyme aromatase is capable of synthesizes estrogen. Thus drugs aromatase inhibitors are capable of either undermining the production of estrogen or blocking estrogen’s action.