Treatment related psychological distress during adjuvant chemotherapy as a conditioned response

Patients receiving cycles of cytotoxic chemotherapy for cancer often experience noxious side effects following treatments and may develop classically conditioned side effects, such as anticipatory nausea and vomiting (ANV) during the course of repeated infusions. The present study explored the possibility that classical conditioning processes may also contribute to treatment related psychological distress. Sixty-six patients, scheduled for adjuvant chemotherapy for breast cancer (stages I, II, IIIa), agreed to participate. Patients were assessed in the clinic on the first day of every chemotherapy cycle and in their homes three to five days before their final cycle. Patients experienced considerable psychological distress during the course of chemotherapy, and particularly before the first infusion. Prior to the last cycle of chemotherapy, psychological distress was significantly higher in the clinic environment than in patients' homes. Consistent with classical conditioning, psychological distress did not escalate over the days before treatment, but rather increased abruptly when patients returned to the clinic. The results of the present study indicate that several factors are involved in patients' anticipatory psychological distress and highlight the potential contribution that conditioning processes may make to patients' emotional distress in the clinic environment.