Due to concern about possible negative effects of systemic chemotherapy on cognitive function (i.e. memory and concentration), these functions in cancer patients after such treatment have received increasing clinical and public attention. However, in 2005, at the
onset of the research project leading to this thesis, no neuropsychological studies had been published on cognitive function in testicular cancer patients (TCPs) after systemic chemotherapy. TCPs in general are young and have a favorable prognosis. Hence, most patients have a long life expectancy after their malignancy, and they are expected to resume a regular professional and familial life after treatment. Cisplatin, the cornerstone of chemotherapy for testicular cancer, has well-known toxic effects on the peripheral nervous system. Therefore we considered systematic assessment of cognitive function in TCPs treated with chemotherapy to be of considerable importance, both for the patients and for future clinical work.
The main aim of this thesis was to explore cognitive function in TCPs. In the period from 2006 to 2009 we therefore conducted a prospective study of cognitive function in TCPs evaluated and treated at the Norwegian Radium Hospital and the Ullevaal University Hospital (now both parts of the Oslo University Hospital). This thesis also includes a prospective study on self-reported cognitive complaints in TCPs included in three European Organization of Research and Treatment of Cancer Organization (EORTC) / Medical Research Council (MRC) treatment studies done during the 1990’ies, before the associations between chemotherapy and reduced cognitive function became a public concern.
In paper I (the 1990’ies study) self-reported cognitive complaints in TCPs treated with chemotherapy or radiotherapy during the 1990’ies are prospectively explored. We found no significant difference between the chemotherapy and the radiotherapy group in prevalence of cognitive complaints at one-year follow-up. Treatment modality was not significantly associated with cognitive complaints at any time point after adjustment for QoL domains such as emotional function and fatigue.
Paper II-IV reports results from our prospective study of cognitive function in TCPs, conducted at the Oslo University Hospital (“The Oslo-study”). In paper II (the distress paper) we explored the level of emotional distress shortly after the diagnosis of TC (at the baseline evaluation of our study), and investigated whether current level of distress had any impact on the neuropsychological test results at that time-point. About one-fourth of the TCPs had clinically significant distress at baseline. However, we found that the majority of neuropsychological test scores (14 out of 18) were not significantly associated with levels of emotional distress.
In paper III (the neuropsychological paper) we compared the proportions of TCPs in three treatment groups (no chemotherapy, one cycle of chemotherapy, and multiple cycles of chemotherapy) with changes in neuropsychological test performance from baseline (pretreatment) to one year follow-up. No significant group differences in proportions of TCPs with a decline in neuropsychological test performance from baseline to follow-up were observed.
In paper IV (the self-report paper) we prospectively explored self-reported cognitive complaints in TCPs. Increase of cognitive complaints from baseline to one-year follow-up was significantly associated with levels of emotional distress and fatigue and treatment with chemotherapy, but not with a decline in neuropsychological test performance.
From the findings presented in this thesis we conclude that cisplatin-based chemotherapy does not seem to have a negative impact on neuropsychological test performance in TCPs at one year follow-up. However, this finding should be confirmed in larger prospective studies before definite conclusions can be made. Self-reported cognitive complaints were not associated with neuropsychological test performance in our study, but were related to current emotional distress and fatigue. For TCPs treated in the 1990’ies, chemotherapy was not a significant predictor of post-treatment cognitive complaints after adjustment for emotional function and fatigue.
List of papers. Paper II is removed from the thesis due to copyright restrictions.
A prospective study of cognitive complaints in testicular cancer patients treated in the pre “chemo brain” era.
Skaali T, Fosså SD, Dahl AA. Submitted manuscript.
Published as: A Prospective Study of Cognitive Complaints in Patients With Testicular Cancer
Clinical Genitourinary Cancer, Volume 9, Issue 1, pages 6-13
Is psychological distress in men recently diagnosed with testicular cancer associated with their neuropsychological test performance?
Skaali T, Fosså SD, Andersson S, Langberg CW, Lehne G, Dahl AA.
Psycho-Oncology, Volume 20, Issue 4, pages 369–377, 2011
A prospective study of neuropsychological functioning in testicular cancer patients.
Skaali T, Fosså SD, Andersson S, Cvancarova M, Langberg CW, Lehne G, Dahl AA. Accepted manuscript.
Annals of Oncology, Volume 22, Issue 5, pages 1062-1070, 2011
Self-reported cognitive problems in testicular cancer patients: Relation to neuropsychological performance, fatigue and mental distress.
Skaali T, Fosså SD, Andersson S, Cvancarova M, Langberg CW, Lehne G, Dahl AA.
Journal of Psychosomatic Research, Volume 70, Issue 5, pages 403-410, May 2011. Accepted manuscript.