The rate of depression within the cancer patient population may be more significant than that of suicide. A study published in 2014 found that nearly 1 in 3 people with cancer (31.8%) experienced depression, anxiety, or some form of adjustment disorder.4

“The highest prevalence for any mental disorder was found in patients with breast cancer (41.6%; 95% CI, 36.8% to 46.4%), followed by patients with head and neck cancer (40.8%; 95% CI, 28.5% to 53.0%),” the authors wrote. “The lowest prevalence was found in patients with pancreatic cancer (20.3%; 95% CI, 8.9% to 31.6%) and stomach/esophagus cancers (21.2%; 95% CI, 12.8% to 29.6%).”

As the CDC researchers explained, “A multitude of factors can arise to cause this distress, from fears of death and suffering, to changes in social roles and the physical pain caused by cancer or its treatments, to having a personal history of depression or anxiety disorders. Although some survivors might be affected minimally or temporarily, others might experience overwhelming anxiety, depression, or both, for significant periods of time, causing disruption and a reduced quality of life.”

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And, they continued, the effects are not limited to purely psychological impacts. Depression can affect patient outcomes, as well.

If left unaddressed and untreated,” they wrote, “anxiety and depression in cancer survivors have been found to negatively affect health behaviors, the body’s inflammatory response, and even survival.”

Despite the widespread recognition of the association between cancer and depression, researchers suspect the reported rates may only be the tip of the iceberg.

“Depression in cancer patients is thought to be highly underdiagnosed, with one study pointing out that 93% of patients self-reported symptoms of depression, whereas only 22% were actually classified as depressed at some point during treatment,” wrote researchers from King’s College London, England, in a 2017 study examining the potential link between the chemotherapy drug temozolomide and depression.5

“The devastating nature of cancer makes it difficult to discern any effects of psychosocial stress from potential side effects of the treatment…” wrote the investigators.

And, the actual mechanism by which a medication might trigger depression is difficult to ascertain.

In the case of prostate cancer, patients are commonly treated with androgen deprivation therapy (ADT). A meta-analysis by Dr Nguyen and colleagues found a 41% higher relative risk of depression for patients who received ADT.However, it could be that the side effects of ADT, rather than the hormone therapy itself, sparked depressionsymptoms.

“When you put a man on androgen deprivation therapy,” Dr Nguyen explained, “he gets fatigue, he gains weight, he loses interest in sex, his muscles start to decline, [his] testicles start to shrink. And these are events that could, in theory, lead to depression.”

The researchers from the King’s College study found a potentially causal link between temozolomide and depression by examining the drug’s impact on neurogenesis in mice.

“The results from numerous studies in which neurogenesis is depleted using various methods show the development of some depressive-like symptoms in some studies but not others, indicating that the idea that a decrease in neurogenesis simply results in immediate depression is unlikely,” the researchers stated. “However, a consistent finding is that new neurons are required for antidepressant efficacy.”5

Extrapolating from there, the researchers were able to demonstrate that “chemotherapy-induced decreases in neurogenesis results in previously unreported behavioral and biochemical consequences.”

“These results, we argue, are indicative of a biological mechanism, which may contribute to the development of depression in patients being treated with chemotherapy and is separate from the mental distress resulting from a cancer diagnosis.”

The significance of their findings, they concluded, extended beyond a possible link between temozolomide and depression.

“Although no changes in depressive-like behavior have been noted in other studies, it is likely that other types of chemotherapy may similarly affect behaviors and biological parameters, which have the potential to contribute to depression.”

References 

  1. Qato DM, Ozenberger K, Olfson M. Prevalence of prescription medications with depression as a potential adverse effect among adults in the United StatesJAMA. 2018;319(22):2289-2298. doi:10.1001/jama.2018.6741
  2. Hawkins NA, Soman A, Lunsford NB, Leadbetter S, and Rodriguez JL. Use of medications for treating anxiety and depression in cancer survivors in the United StatesJ Clin Oncol. 2017;35(1):78-85. doi: 10.1200/JCO.2016.67.7690
  3. Rahouma M, Kamel M, Nasar A, et al. Lung cancer patients have the highest malignancy-associated suicide rate in USA: a population-based analysis. Abstract presented at: American Thoracic Society International Conference; May 23, 2017; Washington, DC.
  4. Mehnert A, Brähler E, Faller H, et al. Four-week prevalence of mental disorders in patients with cancer across major tumor entitiesJ Clin Oncol. 2014 32(31);3540-3546. doi: 10.1200/JCO.2014.56.0086
  5. Egeland M, Guinaudie C, Du Preez A, et. al. Depletion of adult neurogenesis using the chemotherapy drug temozolomide in mice induces behavioural and biological changes relevant to depressionTransl Psychiatry. 2017;7(4):e1101.
  6. Nead KT,Sinha S,Yang DD,Nguyen PL.Association of androgen deprivation therapy and depression in the treatment of prostate cancer: a systematic review and meta-analysisUrol Oncol.2017;35(11):664.e1–664.e9. doi: 10.1016/j.urolonc.2017.07.016