To Örebro University

Purpose: To examine whether undergoing diagnostic workup leading up to a cancer diagnosis entrails increased risks for depression, anxiety disorder, substance use disorder, somatoform/conversion disorder, severe stress and adjustment disorder.

Methods: Based on the nationwide health registers in Sweden, we conducted a matched cohort study during 2001–2010, including 304,118 cancer patients and five cancer-free individuals per cancer patient randomly selected from the Swedish population and matched on year of birth and sex. Flexible parametric survival models were used to estimate the time-varying hazard ratios [HRs] of any first in-/outpatient diagnosis of the studied psychiatric disorders from two years before cancer diagnosis (Year−2), through the time at diagnosis (Year 0), until ten years after diagnosis (Year 10).

Results: The overall risk for the studied psychiatric disorders started to increase from Year−1 (HR 1.2, 95% confidence interval [CI] 1.0–1.5), peaked immediately after diagnosis (Week 1: HR 12.9, 95% CI 9.4–17.8), and decreased rapidly thereafter to be comparable with cancer-free individuals at approximately Year 10 (HR 1.0, 95% CI 0.8–1.3). The risk elevation was clear for all main cancer types except for non-melanoma skin cancer; and was stronger for cancers of relatively poor prognosis after (P= 0.0005) but not before diagnosis (P= 0.47).

Conclusion: Patients recently diagnosed with cancer experience a dramatic increase in risks of psychiatric disorders. The clear risk elevation during the year before diagnosis suggests an impact of cancer symptoms pre-diagnosis as well as the stress of undergoing clinical evaluation for a suspected malignancy. This work is supported by Cancerfonden and FORTE.