Thesis defense Linda Cillessen (Donders series 495)

27 May 2021

Promotors: Prof. dr. A.E.M. Speckens, Prof.dr. M.L. van der Lee 
Co-promotor: M.O.M. van de Ven

Unraveling the effects of face-to-face and internet-based mindfulness-based interventions for cancer patients: moderating and mediating factors

A third of all cancer patients and survivors experience significant psychological distress, for instance symptoms of depression or anxiety. Increasing evidence shows that mindfulness-based interventions (MBIs) are effective in reducing distress. Therefore, this thesis unraveled the effects of MBIs for cancer patients, focusing on working mechanisms and treatment moderators. A meta-analysis was conducted, and data from a large (N=245) randomized controlled trial, comparing a group MBI and internet-based MBI with usual care, were subjected to secondary analyses.
We found that MBIs are effective in reducing psychological distress in cancer patients, with enduring long-term effects. Increases in mindfulness skills and decreases rumination and fear of the cancer’s recurrence are mediators of these effects. Furthermore, MBIs may temporarily increase negative affect, possibly due to exposure to suppressed negative emotions. Finally, some patients benefit more from MBIs than others. Although cancer-related characteristics (e.g. type, stage, time since diagnosis) do not seem to relate to outcomes, age and some personality factors do. Finally, MBIs with major adaptations (e.g. extra components or shorter versions) are less effective. Online MBIs are a fair option, but not for all patients. All in all, MBIs are a valuable treatment option for cancer patients and survivors, and should be considered and available when patients express a need for psycho-oncological care.