Subjective cognitive dysfunction in breast cancer patients: a systematic review

Objective: Results from studies examining subjective cognitive dysfunctioning (SCD) in breast cancer (BC) patients are unclear. Therefore, this review examined (i) the prevalence of SCD, (ii) the differences between (treatment) groups in SCD, (iii) the course of SCD, (iv) the relationship of SCD with psychological factors, and (v) the relationship between SCD and objective cognitive dysfunctioning (OCD). Methods: Through a systematic literature search, we identified 27 studies concerning SCD in BC patients. The methodological quality of these studies was examined according to predefined criteria. The methodological limitations and heterogeneity across studies were taken into account. Results: Eight studies were graded of high, 12 of moderate, and seven of low quality. Twenty-one to 90% of the patients reported SCD. The comparison between different (treatment) groups, at different time points of the cancer trajectory, rendered inconclusive evidence regarding the relation of SCD to the cancer itself, chemotherapy, and hormonal therapy. SCD and OCD were unrelated, but SCD was associated with psychological distress, fatigue, and health status. Conclusions: SCD does exist in BC patients, but it remains unclear if this is more commonly found in BC patients than in the general population. It is inconclusive if SCD is developed post-treatment or already exists pretreatment. Since there is a relationship between SCD and anxiety and depression, SCD may be more indicative of emotional distress instead of OCD. Attention toward SCD in future research is warranted in order to draw valid conclusions regarding SCD in BC patients. Copyright (C) 2009 John Wiley & Sons, Ltd.