Negative Expectations Can Influence Cancer Drug Adherence


Patients with negative expectations about breast cancer treatment had nearly twice the amount of side effects.

A recent study found that the severity and amount of side effects experienced during cancer treatment may be influenced by a patient’s expectations.

In a study published by Annals of Oncology, patients treated with tamoxifen for breast cancer who had poor expectations for their treatments experienced more and worse side effects. The researchers found that the patients with negative expectations had twice the amount of side effects than women who had positive or neutral expectations.

These findings are significant since patients may cease adjuvant hormone treatment if they experience too many side effects and poor health-related quality of life, according to the study. This can affect how successful the treatment is and impact survival.

Interventions such as counselling could lower the risk of experiencing worse side effects and improve adherence.

“Our results show that expectations constitute a clinically relevant factor that influences the long-term outcome of hormone therapy,” said lead researcher Yvonne Nestoriuc. “Expectations can be modified so as to decrease the burden of long-term side effects and optimize adherence to preventive anti-cancer treatments in breast cancer survivors.”

Included in the study were 111 patients who had surgery for hormone receptor positive breast cancer. Patients were scheduled to start adjuvant hormone therapy with tamoxifen or aromatase inhibitors, such as exemestane, according to the study.

Researchers assessed their expectations about the treatment at the baseline, at 3 months, and at 2 years. Approximately 8% of patients expected no side effects, 63% expected mild side effects, and 29% expected moderate-to-severe side effects, the researchers reported.

Patients who later dropped out of the trial reported more side effects at 3 months than patients who remained in the study. Researchers found that 87% of patients with positive or neutral expectations remained adherent at 2 years, compared with 69% of patients with negative expectations.

Patients who had negative expectations had a 1.8% increase in occurrence of side effects after 2 years, and had a poor quality of life. Side effects experienced by patients were join pain (71%), weight gain (53%), and hot flashes (47%) that were directly attributable to the treatment, according to the study.

Back pain (31%), breathing problems (28%), and dizziness (26%) were also experienced, but could not be attributed to the treatment.

“This substantiates the conclusion that psychological mechanisms such as negative expectations about the treatment play a significant role in the side effects breast cancer patients experience,” said Nestoriuc. “Higher negative expectations, formed by patients before the start of their adjuvant therapy, seem to have a pronounced influence on long-term tolerability, especially once they are confirmed by initially high side effects after 3 months.”

Researchers are currently conducting a controlled trial to determine whether improving treatment expectations can improve outcomes, the study concluded.

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