Epidemiology and management of depression in cancer patients

Abstract

Depression is the most frequent psychiatric comorbidity in cancer patients especially those in terminal stage. Despite the large amount of studies on depression in cancer patients, there are a lot of unanswered questions with respect to diagnosis, prevalence and treatment. Diagnosing depression in cancer patients is a challenge due to the overlapping of depressive symptoms with physical symptoms of cancer. Several alternative diagnostic approaches were introduced to overcome this matter. We reviewed the current state of evidence regarding the clinical relevance of the alternative diagnostic approaches and only manage to identify three studies that compared two or more of the diagnostic criteria. The results showed that the prevalence of depression varied when using different sets of diagnostic criteria. We conducted a meta-analysis on the prevalence of depression in cancer patients. The estimated prevalence of the pooled result of 31 studies using standardized diagnostic criteria based on DSM (SCID) was 10.8%. The figure would have been considerably higher if the whole spectrum of depression such as minor depression, dysthymia and adjustment disorder with depressed mood were included. In the same study, we also discovered that the number of randomised, controlled trials on depression in cancer patients was limited. Despite the difficulties in identifying psychiatric disorders in cancer patients, psychotropic drugs were commonly prescribed in this group of patients. In a study, we investigated the rate of psychiatric comorbidity and psychotropic drugs prescription in terminal patients in the general practice setting. We found that half of the terminal patients (50.3 %) were prescribed psychotropic’s, but only 13.6% of them had also been assigned a psychiatric diagnosis. This sharp contrast was explained by the fact that psychotropic drugs are also prescribed for non-psychiatric complaints. In addition this is also related to the pragmatic approach adopted by the general practitioner. The use of conventional antidepressants in cancer patients is hampered by the delay in action. In view of the short life span of palliative cancer patients, treatment with rapid response is needed. We conducted a 4 week, randomized, double-blind, placebo-controlled study of methylphenidate as add on therapy of mirtazapine in the treatment of major depressive disorder in cancer patients under palliative care. 88 palliative care cancer patients with major depression were included in the study. The result demonstrated significant early response as early as at day 3 in patients treated with methylphenidate as add on therapy. In conclusion, timely, adequate diagnosis and antidepressant treatment with rapid response are some of the unmet need in the management of depression in cancer patients. Without a valid and clinically applicable diagnostic tool, the challenge remains to identify depression in cancer patients and hence to study its prevalence. The use of conventional antidepressants is limited by the delay in their antidepressant activity. The efficacy of methylphenidate with its rapid onset as an alternative, needs to be confirmed in direct comparison to antidepressant medication.