Risk of death from all causes is 45% higher in women with breast cancer and a subsequent diagnosis of depression, according to a study published in Psycho-Oncology (doi:10.1002/pon.4037). This finding could help identify those women most at risk for depression and in need of support.

The study, led by King’s College London in the United Kingdom, analyzed cancer registration and hospital records for 77 173 women in southeast England with breast cancer diagnosed between 2000 and 2009 and followed them until the end of 2010. Of these, 422 had a history of depression prior to their breast cancer diagnosis and 533 received new diagnoses of depression after their cancer was diagnosed.

After considering factors such as older age at cancer diagnosis, cancer stage at diagnosis, socioeconomic status, and comorbidities, the association between a new diagnosis of depression and decreased survival remained. The relative risk of death (hazard ratio) over the follow-up period was 1.45 times higher in women with cancer and newly diagnosed depression than for those women without depression recorded in that time.

Because the study measured death from all causes, lower survival rates among the women with new depression diagnoses could have been due to cancer progression or any other adverse effect of depression that increases risk of death.

“Low mood and depression are understandable reactions to a breast cancer diagnosis,” said coauthor Elizabeth Davies, PhD, from the Division of Health and Social Care Research and Cancer Studies at King’s College London. Although clinicians know to screen patients for depression, these study findings emphasize the need to ask patients with breast cancer about their mood and for women to know they can ask for help. Women need to feel they can talk about their feelings and not feel guilty about difficulty with coping or depression, which can be a natural response to a cancer diagnosis, explained Davies.

Depression-linked behaviors such as a less healthy lifestyle, chronic stress, and difficulty receiving or adhering to treatment may contribute to decreased survival.

Survival was decreased in women with a prior history of depression, but the association was mostly linked with older age at diagnosis, lower socioeconomic status, and more advanced cancer at diagnosis. Overall, 55% of women with a history of depression were alive 5 years after their breast cancer diagnosis compared with 75% who did not have a history of depression.

A limitation to this study is that medical notes could be incomplete, and hospital records are less likely to have notes on less severe depression. These researchers found depression in 1.2% of medical records for patients with breast cancer, whereas other studies in which breast cancer surgery patients were directly questioned found depression reported for approximately 10% to 25% of patients.