title: Social networks, social support and burden in relationships, and mortality after breast cancer diagnosis.
abstract: Though larger social networks are associated with reduced breast cancer mortality, there is a need to clarify how both social support and social burden influence this association. We included 4,530 women from the Women's Health Initiative who were diagnosed with breast cancer between 1993 and 2009, and provided data on social networks (spouse or intimate partner, religious ties, club ties, and number of first-degree relatives) before diagnosis. Of those, 354 died during follow-up, with 190 from breast cancer. We used Cox proportional hazards regression to evaluate associations of social network members with risk of post-diagnosis mortality, further evaluating associations by social support and social burden (caregiving, social strain). In multivariate-adjusted analyses, among women with high but not low social support, being married was related to lower all-cause mortality. By contrast, among women with high but not low social burden, those with a higher number of first-degree relatives, including siblings, parents, and children, had higher all-cause and breast cancer mortality (among caregivers: 0-3 relatives (ref), 4-5 relatives, HR = 1.47 (95% CI: 0.62-3.52), 6-9 relatives, HR = 2.08 (95% CI: 0.89-4.86), 10+ relatives, HR = 3.55 (95% CI: 1.35-9.33), P-continuous = 0.02, P-interaction = 0.008). The association by social strain was similar though it was not modified by level of social support. Other social network members were unrelated to mortality. Social relationships may have both adverse and beneficial influences on breast cancer survival. Clarifying these depends on understanding the context of women's relationships.
authors.affiliation: Kaiser Permanente, Division of Research, 2101 Webster, 20th Floor, Oakland, CA 94612, USA. Candyce.h.kroenke@kp.org
authors.forename: Candyce H
authors.initials: CH
authors.lastname: Kroenke
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Michael
authors.forename: Hilary
authors.initials: H
authors.lastname: Tindle
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Gage
authors.forename: Rowan
authors.initials: R
authors.lastname: Chlebowski
authors.forename: Lorena
authors.initials: L
authors.lastname: Garcia
authors.forename: Catherine
authors.initials: C
authors.lastname: Messina
authors.forename: Joann E
authors.initials: JE
authors.lastname: Manson
authors.forename: Bette J
authors.initials: BJ
authors.lastname: Caan
mesh_terms: D001943:Breast Neoplasms / Q000175:diagnosis* / Q000401:mortality / Q000523:psychology*; D017281:Cost of Illness; D005190:Family; D005260:Female; D006801:Humans; D017533:Marital Status; D008875:Middle Aged; D015999:Multivariate Analysis; D017698:Postmenopause; D016016:Proportional Hazards Models; D012067:Religion; D012307:Risk Factors; D060756:Social Networking; D012944:Social Support