About Research in Context
In this article, the authors of recent scholarship have been asked to discuss the implications of their research on federal health care providers and specifically the veteran and active-duty service member patient populations. Because the article does not include new research and cannot be blinded, it has undergone an abbreviated peer review process. The original article can be found at Sullivan DR, Forsberg CW, Ganzini L, et al. Longitudinal changes in depression symptoms and survival among patients with lung cancer: a national cohort assessment. J Clin Oncol. 2016;34(33):3984-3991.
Although depression is common among patients with cancer, patients with lung cancer are at particularly high risk. The prevalence of major depressive disorder (MDD) among patients with cancer can be as high as 13%, whereas up to 44% of patients with lung cancer experience depression symptoms at some point following their cancer diagnosis.1-3 These estimates are consistently higher than those of other types of cancer, possibly related to the stigma of the disease and the associated morbidity and mortality that are its hallmarks.4-8 This potentially life-threatening cancer diagnosis often evokes psychological distress; however, additional stressors contribute to the development of depression, including the effects of chemotherapeutic agents, surgical procedures, radiotherapy, and the consequences of physical symptoms and paraneoplastic syndromes.
In addition to the crippling effects of comorbid depression on patients’ quality of life (QOL), severe and persistent depression among patients with cancer is associated with prolonged hospital stays, worse treatment adherence, physical distress and pain, and increased desire for hastened death.9-11 During treatment, depression can amplify physical symptoms and interfere with effective coping.12,13
Depression also is likely a significant factor for the risk of suicide, which is 4 times higher in patients with lung cancer than that of the general population.14 Most important, as our recent study demonstrated, depression that develops at cancer diagnosis or during cancer treatment may contribute to worse survival. This effect was strongest among patients with early stage disease, in other words, the patients who are most likely to achieve cure.3 This association with early stage disease also has been observed in a strictly veteran population from the northwest U.S.15
Another key finding of our study was the similar survival among patients who experienced a remission of their depression and those who were never depressed. This finding reinforces the importance of effective depression treatment, which has the potential to reduce depression-related mortality; however, depression treatment was not fully captured and could not be directly compared in our study. Unfortunately, comorbid depression often goes undiagnosed and untreated in cancer patients as they report unmet emotional needs and a desire for psychological support during and after completion of cancer treatment.16,17
Given the general lack of depression treatment that occurs in patients with cancer, the negative consequences of depression can be sustained well into survivorship—defined clinically as someone who is free of any sign of cancer for 5 years. Cancer survivors frequently report fatigue, mood disturbance, sleep disruption, pain, and cognitive limitations that significantly impact QOL and are associated with disability and increased health care use.18 These symptoms likely are intertwined with and contribute to the development and persistence of depression. The ramifications of untreated depression on long-term cancer survivor outcomes are not completely understood, as few high-quality studies of depression in cancer survivors exist. However, in a mixed group of patients with cancer, there was a 2-fold risk of mortality in survivors with depression symptoms when these patients were assessed from 1 to 10 years into survivorship.19 The impact of depression on cancer survivorship is an important aspect of cancer care that deserves significantly more attention from both a research and clinical perspective.
Special Considerations for Veterans
There is a higher prevalence of mental health diagnoses in veterans than that in the general population, and depressive disorders are the most common.20-22 According to the VA National Registry for Depression, 11% of veterans aged ≥ 65 years have a diagnosis of MDD, a rate more than twice that in the general population of a similar age.23 However, the actual rate of depression among veterans may be even higher, as studies suggest depression is underdiagnosed in the veteran population.24 In addition to depression, veterans experience other disabling psychological illnesses, such as posttraumatic stress disorder (PTSD) related to deployment and combat duty or combat-related injuries, such as traumatic brain injuries. The negative consequences of PTSD on cancer outcomes are largely unexplored, but PTSD can contribute to increased health care utilization and costs.25,26 A similar psychological construct, cancer-related posttraumatic stress (PTS), which develops as a result of a cancer diagnosis or treatment, is associated with missed medical appointments and procedures, which could impact survival.27