INTRODUCTION: The present study aims to examine the process of mutual influence in older couples with cancer diagnosis by studying their risk of depression. MATERIALS AND METHODS: 282 couples with one spouse diagnosed with cancer were selected from the Three-City cohort study. Dyadic analyses were used to determine whether trait anxiety affects the risk of depression and whether a mutual influence process occurs prior and post cancer diagnosis. Cross-sectional analyses were performed at two time-points: before and after receiving the diagnosis. RESULTS: A higher level of anxiety among cancer patients resulted in a decreased risk of depression among spousal caregivers. Moreover, a higher anxiety among spousal caregivers increased their own risk of depression, but it didn't influence depression risk among cancer patients. While there is an intra-individual relationship between a higher level of trait anxiety and a greater risk of depression prior to cancer diagnosis, there is no cross-influence between spouses. DISCUSSION: The study findings indicate that a dyadic psychological adjustment process might help older adults to cope with cancer by limiting the risk of depression among spousal caregivers.