CYP2D6 pharmacogenetic testing: Beliefs and psychological effects in breast cancer patients treated with adjuvant tamoxifen (T).

Abstract

e20541 Background: Pharmacogenetic tests (PGT) are intended to predict the efficacy and toxicity of a specific treatment. There is a common concern that they may be misunderstood by patients (pts), confused with predictive tests for hereditary disorders and induce psychological distress. Methods: As part of a study aimed at correlating individual T activation capability with disease recurrence, CYP2D6 genotyping was offered to 203 early breast cancer pts. On enrolment, they received complete verbal and written information by their oncologist about the test and its purpose. Six months later they were asked to answer 4 questions concerning the nature and the possible psychogenic stress aroused by PGT. Their level of anxiety was assessed by the Zung-Self-Rating anxiety scale. Results: Anxiety was absent in 39%, within the normal limits in 50% or mild in 9% of pts. Only two pts had a moderate score. Anxiety was not associate with age or time from cancer diagnosis. Although not significantly, its score was higher in pts with larger tumors and positive lymph nodes. All pts agreed on the usefulness of PGT to enable the prediction of differences in drug response and toxicity. Some of them believed that they could predict some disease risks: the misperception was higher among elderly pts (> 70y, 50%) while was infrequent in younger pts (<39y, 12%). There was no association with the anxiety score. PTG related worries, although not generating a clinically detectable anxiety, were reported by 0%, 10% and 16% of all pts <39, 40-69 and >70 years old, respectively. Conclusions: CYP2D6 genotyping to predict tamoxifen activation was welcomed, well understood and was not associated with anxiety in the majority of breast cancer pts on adjuvant treatment. It seems that, when properly informed by their physician, patients show a positive attitude towards PG testing and no psychological distress. Funded by Regione Veneto. Clinical trial information: 532.