Neuropsychological performance in cancer patients: the role of oral opioids, pain and performance status.

The aim of the present study was to evaluate the possible influence of oral opioids, pain and performance status on some aspects of psychomotor function and cognition in cancer patients. One hundred and thirty cancer patients between 40 and 76 years of age were consecutively included in the study. In order to separate the impact of performance status, pain and oral opioids on neuropsychological functioning the patients were allocated in a cross-sectional design to five different groups. Group 1 (N=40), which was considered the control group, was characterized by being in Karnofsky Performance Status (KPS) A ('Able to carry on normal activity and work. No special care is needed'), had no pain and received no oral opioid medication. Group 2 (N=19) was characterized by being in KPS B ('Unable to work. Able to live at home and care for most personal needs. A varying degree of assistance is needed'), had no pain and received no oral opioid medication. Group 3 (N=19) was characterized by being in KPS B, had pain, but received no oral opioid medication. Group 4a (N=31) was characterized by being in KPS B, had pain and received stable doses of oral opioids. Group 4b (N=21) was characterized by being in KPS B, had no pain and received stable doses of opioids. Assessments comprised pain intensity, sedation, opioid doses, time from ingestion of last opioid dose to testing and opioid side effects. The neuropsychological tests used were continuous reaction time (CRT), finger tapping test (FTT) and paced auditory serial addition task (PASAT). Regarding the neuropsychological tests group 1 was compared with each of the other groups and respecting the hierarchy of increasing numbers of stigmatizing factors group 1 was compared with group 2, group 2 with group 3 and so forth. Concerning CRT, group 1 performed statistically significantly faster than groups 2, 4a and 4b. Concerning FTT, group 1 performed statistically significantly faster than groups 3 and 4a. Concerning PASAT, groups 1 and 4b performed statistically significantly better than group 4a. Furthermore, the pain-relieved groups 2 and 4b performed statistically significantly better in PASAT than the pain-suffering groups 3 and 4a. We conclude that in cancer patients the impact of stigmatizing factors (oral opioids, pain and reduced performance status) seems to impair some important aspects of neuropsychological performance, but more specifically our results indicate that (1) the use of long-term oral opioid treatment in cancer patients per se did not affect any of the neuropsychological tests used in the present study, (2) cancer patients being in KPS B had statistically significantly slower CRT than patients being in KPS A and (3) pain itself may deteriorate the performance of PASAT more than oral opioid treatment.