Depression is common in patients with cancer and is associated with poor quality of life and worse disease outcomes. A first-ever systematic review and meta-analysis of earlier studies has found that certain measurable indicators of inflammation typically found in patients with cancer may provide a useful, screenable indication as to which of them may be at risk for depression. The new study was recently published in the journal Cancer.
Previous studies have suggested that inflammation may contribute to depression in oncology patients, but they have yielded inconsistent findings because of small sample sizes and patients with different types of cancers in different stages of treatment.
In the new examination of 47 individual studies, including more than 4,200 patients with cancer, researchers from Winship Cancer Institute of Emory University, in collaboration with colleagues from Memorial Sloan Kettering Cancer Center and Northwell Health/Lenox Hill Hospital/Manhattan Eye, Ear Throat Hospital, found a robust relationship between depression and inflammation, shedding new light on how patients with cancer develop depression. Such a comprehensive review can overcome the limitations of individual studies.
Based on their review, the researchers found that patients with cancer and depression exhibited reliable increases in several inflammatory molecules, including interleukin-6, tumor necrosis factor and C-reactive protein (CRP).
"Cancer and its treatment with surgery, radiation and chemotherapy are often associated with increased inflammation," says the study's lead author, Daniel C. McFarland, DO, a medical oncologist at Northwell Health/Lenox Hill Hospital/Manhattan Eye, Ear Throat Hospital. He adds, "Our findings suggest that these inflammatory molecules can identify patients with cancer at risk for depression." One of the inflammatory molecules identified in the study, CRP, is routinely measured in laboratories across the US, and therefore may be especially useful as a screening test for this purpose.
Senior author, Andrew H. Miller, MD, research director of psychiatric oncology at Winship Cancer Institute of Emory University and the William P. Timmie Professor of Psychiatry and Behavioral Sciences at Emory University School of Medicine, suggests that screening for increased inflammation in patients with cancer who are depressed may also help guide antidepressant therapy. He points out that certain anti-depressant medications are likely to be more effective than others.
"Several studies indicate that depressed patients with increased inflammation may not do as well on drugs that primarily affect serotonin, such as fluoxetine, paroxetine and escitalopram," says Miller. "These are often the frontline drugs used to treat depression." He suggests that antidepressant drugs that affect dopamine, such as bupropion, may work better. Miller cautions, however, that studies are underway to test this hypothesis, noting that "while there is promise, we need proof."
Blocking inflammation itself may be the most effective strategy, but there are currently only a few medication options for this purpose. For this reason, McFarland says, "Probably the best way to reduce inflammation for now is through diet and exercise."