Patients prescribed tamoxifen may not report when they interrupt or discontinue therapy, according to the results of a study published in the Journal of Clinical Oncology.¹ Using blood draws to determine serum levels of tamoxifen among 1,177 premenopausal women with invasive breast cancer, the researchers found that 16% of patients did not meet the tamoxifen threshold level of 60 ng/mL, and these biochemically nonadherent patients had significantly shorter distant disease–free survival. The patient-reported rate of nonadherence to tamoxifen was lower, at 12.3%.

As noted in news coverage of the study (ClinicalTrials.gov identifier NCT02308085), “Although nonadherence to endocrine therapy represents a major obstacle to the achievement of optimal outcomes for these patients, the identification of patients who are nonadherent to such treatment remains challenging.”

“Health-care providers tend to overestimate to what extent patients take their prescribed, long-term, oral treatments,” the researchers noted. “There is other research to suggest we are not really good at predicting who is going to be noncompliant,” coauthor of the study Ann H. Partridge, MD, MPH, FASCO, told The ASCO Post. Dr. Partridge is Professor of Medicine at Harvard Medical School and Vice Chair of Medical Oncology at Dana-Farber Cancer Institute, Boston.

‘A Real Eye-Opener’

“Years ago, when we did our first study of nonadherence with tamoxifen, it was a real eye-opener,” Dr. Partridge said. With a diagnosis as serious and potentially life-threatening as cancer, it was assumed patients would follow the prescribed treatment. However, the results showed people were not much more adherent with tamoxifen than, on average, with blood pressure medication. “Because of the research that shines light on nonadherence, we increasingly are aware of the issue,” she commented.

Dr. Partridge continued: “The hard part is how do you fix it? As a clinician who does research in this area, I think the first way to fix it is to acknowledge with patients that it can be difficult and to work with them. I try to be proactive about side-effect management.” This approach includes giving patients printed materials about managing symptoms at home.

Individual Treatment Decision

“If someone comes to me and is intolerant for whatever reason and is acknowledging it, I have a conversation about the pros and cons of therapy,” Dr. Partridge explained. “I tell them, ‘Make sure you are making a good decision for you.’ You want to make sure patients understand the pros and cons and then make the best decision for themselves, because this is not just a public health issue; it is a personal issue.”

“Then, there is the whole issue of the emotional response to both the cancer and the treatment,” noted Dr. Partridge.” Many people come in and say, ‘I don’t want to take a medication for the rest of my life.’ But they also don’t want breast cancer. What’s the lesser evil?”

“Ideally, you should have a conversation to help support patients for their total medical care, not just for the cancer,” Dr. Partridge said. “There are some interesting data to suggest that when women start a hormone medication, they are more likely to decrease or stop taking their cardiovascular medication as adherently. That is dangerous: Most patients with breast cancer will be long-term survivors. Most won’t get cancer again,” but “a woman can increase the risk of heart disease if she does not take those medicines prescribed. We have to be attentive to this.”

Along the Way

In addition to the initial conversation, discussions are important “along the way, too,” Dr. Partridge stressed. “Many people are kind of gung-ho in the beginning and then can have cancer fatigue,” she said. They may feel conflicted about the value of taking endocrine therapy or feel frustrated by hot flashes, and not take it on the weekends, for example.

“We do usually give women a break when they need it, to help them tolerate their medications,” noted Dr. Partridge. “For those who are having a hard time, we give a week or two off to see if that helps,” she said.

“When I see patients around the time they will need a prescription refill, if they haven’t already talked to me about it, I will say, ‘How is it going taking this? Any issues of getting the prescription or taking it every day?’”

“Usually, after a year or so, I assume someone is going to tell me if there is a problem,” Dr. Partridge added. “But every now and then, I am surprised. Someone will say, ‘I forget a lot.’” When that happens, “I try not to be judgmental. Such women need support and someone to help them to take care of themselves.” 

DISCLOSURE: Dr. Partridge has received royalties for coauthoring the breast cancer survivorship section of UpToDate and has been reimbursed for travel, accommodations, or other expenses by Novartis.

REFERENCE

1. Pistilli B, Paci A, Ferreira AR, et al: Serum detection of nonadherence to adjuvant tamoxifen and breast cancer recurrence risk. J Clin Oncol. June 22, 2020 (early release online).