Depression as a Predictor ofDisease Progression and Mortalityin Cancer Patients

A Meta-Analysis

We read with interest the skillful meta-analysis by Satinet al1 indicating that depression is predictive of all-causemortality, but not disease progression, in cancer patients.We commend the authors for their thoughtful methodol-ogy and interpretations, and wish to highlight importantquestions raised by the article.

How do the effects compare with effects in the generalpopulation? To put their findings in context, the authorsnoted that a comparable meta-analysis found a more ro-bust effect of depression on mortality in patients with car-diac disease. Another meta-analysis (cited by Satin et albut not directly compared with their results) reported an81% higher mortality rate among subclinically and clini-cally depressed individuals in community samples,3

whereas Satin et al found mortality rates to be higher by39% (for clinical depression) and 25% (for depressivesymptoms).1 Thus, the effect of depression on mortalitymay not be greater (and potentially somewhat smaller) incancer patients compared with the general population.

Does depression increase the risk of dying from cancer?Satin et al noted surprise that depression predicted all-

cause mortality but not disease progression.1 However, if

depression is predictive of all-cause (not cancer-specific)

mortality in cancer patients as it is in the general popula-

tion, this effect may have little to do with the effect of

depression on cancer-specific course or outcome (as is

aptly pointed out by Satin et al1). As such, the authors’

postulate that the nonsignificant link between depression

and disease progression in cancer patients is due to the

limited number of extant studies should remain specula-

tive until more research has accrued.What are the implications of the assumed (but contro-

versial) importance of mortality as a primary endpoint of psy-chosocial oncology interventions? Depression can be life-

threatening, and the findings of Satin et al support the

notion that treating depression to prevent mortality is as

important for cancer patients as for anyone else. However,

the findings do not speak directly to the role of interven-

tions for depression in facilitating survival from cancer.

REFERENCES

1. Satin JR, Linden W, Philips MJ. Depression as a predictor ofdisease progression and mortality in cancer patients: a meta-analysis. Cancer. 2009;115:5349-5361.

2. Barth, J, Schumacher M, Hermann-Lingen C. Depression asa risk factor for mortality in patients with coronary heart dis-ease: a meta-analysis. Psychosom Med. 2004;66:802-813.

3. Cuipers P, Smit F. Excess mortality in depression: a meta-analy-sis of community studies. J Affect Disord. 2002;72:227-236.

Stefan Schneider, Dipl. PsychAnne Moyer, PhD

Department of PsychologyStony Brook UniversityStony Brook, New York

DOI: 10.1002/cncr.22318, Published online: April 19, 2010 in WileyInterScience (www.interscience.wiley.com)

Reply to Depression as a Predictorof Disease Progression andMortality in Cancer Patients

A Meta-Analysis

In their correspondence, Schneider and Moyer com-mented on our meta-analysis of prospective studiesregarding depression and cancer1 by calling attention to aprevious meta-analysis by Cuijpers and Smit that we hadcited.2 Cuijpers and Smit had demonstrated a greaterassociation between depression and mortality in the gen-eral population than that presented in our meta-analysis,which was restricted to cancer patients. Schneider andMoyer concluded that the effect of depression on mortal-ity may be potentially smaller in cancer patients comparedwith the general population, and suggested that cancer-specific mortality is unlikely to be affected by depression.We argue here that a discrepancy between meta-analyticfindings derived from different populations does not ruleout a potential cancer-specific association.

The causes of death are not described in themeta-analysis by Cuijpers and Smit, and cardiac diseaseis likely to be a major cause of death in the communitysamples that had been studied. Given that the observedrisk of depression and mortality in cardiac patients isroughly 2:13 and therefore much greater than the ratio

3304 Cancer July 1, 2010

Correspondence

we observed in cancer patients, and that cardiovasculardisease accounts for nearly 50% of all deaths, the resultsin the meta-analysis by Cuijpers and Smit were likelydriven by cardiac deaths in their community samples. Amuch-needed, large-scale prospective study that comparesthe association between depression and mortality out-comes across various causes of death would allow for amore definitive conclusion regarding this point.

Schneider and Moyers also raised the question ofimplications for depression treatment when theobserved risk is only moderately elevated and not verydifferent from that of the population at large. We doknow that depression negatively affects adherence tomedical treatment protocols,4 and that the psychologi-cal treatment of depression can be efficacious inrelieving distress.5 To us, these facts are ample justifi-cation for the proactive identification and treatmentof depression in cancer patients, even if their mortal-ity risk was neither cancer specific nor greater thanthat of the general population.

REFERENCES

1. Satin JR, Linden W, Phillips MJ. Depression as a predictorof disease progression and mortality in cancer patients: ameta-analysis. Cancer. 2009;115:5349-5361.

2. Cuijpers P, Smit F. Excess mortality in depression: a meta-analy-sis of community studies. J Affect Disord. 2002;72:227-236.

3. Barth J, Schumacher M, Hermann-Lingen C. Depression as arisk factor for mortality in patients with coronary heart dis-ease: a meta-analysis. Psychosom Med. 2004;66:802-813.

4. Wing R. The role of adherence in mediating the relationshipbetween depression and health outcomes. J Psychosom Res.2002;53:877-881.

5. Linden W, Satin JR. Avoidable pitfalls in behavioral medicineoutcome research. Ann Behav Med. 2007;33:143-147.

Jillian R. Satin, MAWolfgang Linden, PhDMelanie J. Phillips, BSc

Department of PsychologyUniversity of British ColumbiaVancouver, British Columbia

DOI: 10.1002/cncr.25315, Published online: April 19, 2010 in WileyInterScience (www.interscience.wiley.com)

Cancer July 1, 2010 3305

Correspondence