Commentary

Through meta-analysis, Pinquart and Duberstein have further solidified the importance of psycho-oncology in the treatment of cancer patients by contributing to the growing evidence linking depression with unfavourable cancer outcomes. The analysis yielded results consistent with those from our recent meta-analysis1 but with less stringent inclusion criteria, thus drawing on a larger dataset.

The expansion of the dataset has allowed for some examination of moderating variables, which is a largely understudied and welcome addition to this literature. Age and cancer stage emerged as potential moderators for further investigation. The authors also highlight the non-significant results yielded from the studies using the Beck Depression Inventory (BDI) compared to those that used other self-report measures, hypothesising that the difference may be due to the relatively high proportion of somatic items composing the instrument. Because this explanation contrasts with the expectation that somatic symptoms are a proxy for disease severity, thereby bolstering the association between depression scores and cancer mortality, sample size may be a more viable explanation of the differences found in depression measures. As the authors point out, the analysis of moderators of the relationship of depression and mortality is in its early stages and is restricted by inadequate reporting and limited sample size. Future studies that allow for the testing of moderator variables will be useful in understanding this relationship.

Pinquart and Duberstein have thoroughly synthesised a large body of evidence to demonstrate that depression predicts mortality in cancer patients. To overlook their suggestion for psychological screening would be to miss an important opportunity. Because psychosocial treatment is effective in reducing distress only when initial distress is elevated,2 routine psychological screening optimises treatment benefit and long-term cost savings, by identifying individuals early and efficiently. The Psychosocial Screen for Cancer3 (PSSCAN) is a good example of a screening tool that addresses practical barriers to psychosocial screening. It is a brief, but thorough, psychometrically sound instrument validated within a clinical context. The integration of psychosocial treatment in a medical model is not only helpful to patients, but, as continues to be demonstrated, efficient and evidence based.