However, late-stage breast cancer patients have a higher risk of dying if they suffered from depression before their cancer diagnosis, say Karen Hjerl, M.D., Ph.D. of Rigshospitalet University Hospital in Copenhagen, Denmark and colleagues.
Hjerl and colleagues acknowledge that the relationship between time of depression and cancer stage is "difficult to explain," and suggest that a whole host of factors may contribute to the differences in risk, including potentially better psychiatric care for late-stage patients who spend more time under clinical care.
The patients' ages or specific cancer treatments did not contribute to the different effects of depression for early and late-stage patients, say the researchers. Their study did not include women older than 70, those whose cancer had spread or women with other serious medical conditions.
Hjerl and colleagues took advantage of a unique set of Danish national health registries, which tracked breast cancer patients, their psychiatric admissions and death records, to analyze the effects of depression in 20,593 women.
Post-diagnosis depression in early-stage patients, who have tumors smaller than 50 millimeters in diameter and no underarm lymph nodes, was associated with a slightly elevated risk of cancer death, while having no significant effect on late-stage patients.
Pre-diagnosis depression boosted the risk of death in late-stage patients with larger tumors and lymph node spread. There was some increase in the risk of death for early-stage patients with pre-diagnosis depression, but that was not statistically significant, the study says.
Hjerl and colleagues say that more information about the women's other illnesses, smoking habits and other lifestyle factors, including socioeconomic status, may shed further light on how depression is linked to the risk of death in different stage cancer patients. The exact mechanisms by which depression might interact with breast cancer to cause death are still unknown.
The research was supported by the Danish Cancer Society, Bispebjerg Hospital Copenhagen Hospital Cooperation, the Willy and Ingebord Reinhard Foundation, the Martha and Acel Thomsen Foundation, the Inge and Finn Myrup Foundation, the Inger and Max Wørzners Foundation, and the Theodore and Vada Stanley Foundation.
BY BECKY HAM, STAFF WRITER
HEALTH BEHAVIOR NEWS SERVICE
FOR MORE INFORMATION
Health Behavior News Service: (202) 387-2829 or www.hbns.org.
Interviews: Contact Dr. Karen Hjerl at khjerl@dadlnet.dk.
Psychosomatics: Contact Tom Wise, M.D., at (703) 698-3626.
Journal
Psychosomatics