The Risk of Psychological Stress on Cancer Recurrence: A Systematic Review

SIMPLE SUMMARY: Cancer imposes the largest clinical and economic burden, with an estimated 19.3 million cancer incidents and almost 10.0 million cancer deaths in 2020 worldwide. Despite advances in early diagnosis before cancer progression, there are still feared concerns about recurrence after primary treatments. Psychological stress has been known to contribute to the development and progression of cancer; however, its effect on cancer recurrence remains inconclusive. To determine the association between psychological stress and the risk of cancer recurrence, this review aims to systematically evaluate the relevant studies. This study provides comprehensive information about the importance of psychological stress on cancer recurrence and provides reference data to clinicians and scientists for further studies. ABSTRACT: Cancer recurrence is a significant clinical issue in cancer treatment. Psychological stress has been known to contribute to the incidence and progression of cancer; however, its effect on cancer recurrence remains inconclusive. We conducted a systematic review to examine the current evidence from the Medline (PubMed), Embase and Cochrane Library up to May 2021. Among 35 relevant articles, a total of 6 studies (10 data points) were finally selected, which enrolled 26,329 patients (26,219 breast cancer patients except hepatocellular carcinoma patients in 1 study), 4 cohort studies (8 data points) and 2 RCTs (2 data points). Among the 8 data points in cohort studies, four psychological stress-related factors (two ‘anxiety’, one ‘depression’, and one ‘hostility’) were shown to be moderately related with the risk for cancer recurrence, while ‘loss of partner’ resulted in opposite outcomes. The ‘emotional‘ and ‘mental’ health factors showed conflicting results, and an RCT-derived meta-analysis proved the positive efficiency of psychotherapies in reducing the cancer recurrence risk among breast cancer patients (HR = 0.52; 95% CI 0.33–0.84). Despite the limitations, this study produces comprehensive information about the effect of psychological stress on cancer recurrence and provides reference data to clinicians and scientists for further studies.