Can Pre-Existing Depression Affect Survival in Prostate Cancer?

Introduction 

According to the World Health Organization (WHO), there were approximately 1.4 million new cases of prostate cancer globally, out of which 0.37 million died in 2020. Also, as per the WHO in 2023, about 280 million people were living with depression. Research has revealed links between mental health issues and various types of cancers. 

Prostate cancer is the second most frequent cancer diagnosis made in men and 5^th leading cause of death worldwide. Studies have also shown twice as much prevalence of depression in people with prostate cancer compared with the general population without a diagnosis of cancer. Some studies have found that pre-existing depression accelerates cancer progression. However, the influence of pre-existing depression on cancer survival and mortality is less researched; hence, the authors thought to study the same. 

Aim of the study 

To investigate the association between pre-existing depression and survival rates in prostate cancer patients using data from the Prostate, Lung, Colorectal, and Ovarian (PLCO) cancer screening trial. The follow-up was done for approximately 25 years. 

Methodology

Deidentified data were analyzed and obtained from the National Cancer Institute. The trial commenced in 1993 and was completed in 2016 with approximately 155000 participants who were randomized into either the intervention (screening) or control groups. Patients were identified into

• Prostate cancer with pre-existing depression
• Prostate cancer without pre-existing depression and
• Control participants

Self-reported physician diagnosis or antidepressant use determined the pre-existing state of depression. Association of prostate cancer treatment, cancer stage, or specific cause of death with survival could not be assessed due to limited data. 

38169 patients fulfilled the study inclusion criteria and were included for result analysis.

Results

• 205 patients had prostate cancer and pre-existing depression with a mean age of 61 (+/- 5) years.
• 2096 patients had prostate cancer without pre-existing depression, with a mean age of 61 (+/- 5) years.
• 35868 participants had no cancer nor depression, with a mean age of 61 (+/- 5) years.

Statistical findings

Survival rates among participants with prostate cancer and pre-existing depression were lower when compared with those with cancer and without depression, with a 2.14 hazard ratio and 95% confidence interval. It was also observed in the same group comparison that the long-term survival was poorer in patients with prostate cancer with pre-existing depression. 

It was also found that survival rates among participants with prostate cancer and pre-existing depression were lower when compared to the controlled general population group without either of the diagnoses, with a hazard ratio of 2.51 and a confidence interval of 95%. 

Take-away

This study found that “pre-existing depression was associated with a 2.5-fold increase in mortality risk for patients with prostate cancer.” 

Limitations 

The lack of data to establish an association between cancer treatment, stage, or specific cause of death with survival was not assessed. These unmeasured confounding factors may have influenced research outcomes, as per the authors. 

Further studies are warranted to understand the role of depression in prostate cancer and to explore appropriate interventions to improve quality of life and survival outcomes for these patients. 

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