Socially integrated women were shown to have significantly lower breast cancer death rates and disease recurrence than socially isolated women, found a large Kaiser Permanente study.
“It is well established that women who have more social ties generally, including those with breast cancer, have a lower risk of death overall,” said Dr Candyce H Kroenke, a research scientist with the Kaiser Permanente Northern California division of research and lead author of the study. “Our findings demonstrate the beneficial influence of women’s social ties on breast cancer-specific outcomes, including recurrence and breast cancer death.”
This is believed to be the largest study to date of social networks – the web of personal relationships that surround an individual – and breast cancer survival. Funded by the National Cancer Institute, the study included 9,267 women diagnosed with stages 1 to 4 invasive breast cancer enrolled in the After Breast Cancer Pooling Project, a pooled cohort of four studies of women with breast cancer, including one conducted at Kaiser Permanente Northern California.
Data was collected and analysed from breast cancer survivorship studies conducted in California, Utah, Oregon, Arizona, Texas and Shanghai, China. Researchers examined how a range of lifestyle factors – including exercise, diet, weight management and social factors – affect breast cancer survivorship.
Within two years of a breast cancer diagnosis, women answered surveys about their personal relationships and social networks, including spouses or partners; religious, community and friendship ties; and the number of first-degree, living relatives. They were followed for up to 20 years.
The women were characterised as socially isolated (few ties), moderately integrated, or socially integrated (many ties). The large sample size allowed researchers to control for numerous factors that might confound results.
Compared to socially integrated women, the study found that socially isolated women were: 43% more likely to have a recurrence of breast cancer; 64% more likely to die from breast cancer; and 69% more likely to die from any cause.
Despite these findings, Kroenke noted that the results also point to complexity, in that not all types of social ties were beneficial to all women.
For example, researchers found that older white women without a spouse or partner were 37% more likely to die from breast cancer than older white women with one, a relationship that wasn’t apparent in other demographic groups. By contrast, non-white women with few friendships were 40% more likely to die of breast cancer than those with many friendship ties, and non-white women with fewer relatives were 33% more likely to die of breast cancer than those with many relative ties, relationships that were not apparent in white women.
“The types of social ties that mattered for women with breast cancer differed by sociodemographic factors including race/ethnicity, age and country of origin,” Kroenke noted. “Ultimately, this research may be able to help doctors tailor clinical interventions regarding social support for breast cancer patients based on the particular needs of women in different sociodemographic groups.”
The study builds on previous research by Kroenke and colleagues who found that positive social interactions are related to higher quality of life in breast cancer patients; high-quality personal relationships are related to better survival; and larger networks are related to healthy lifestyle factors.
Background: Large social networks have been associated with better overall survival, though not consistently with breast cancer (BC)–specific outcomes. This study evaluated associations of postdiagnosis social networks and BC outcomes in a large cohort.
Methods: Women from the After Breast Cancer Pooling Project (n = 9267) provided data on social networks within approximately 2 years of their diagnosis. A social network index was derived from information about the presence of a spouse/partner, religious ties, community ties, friendship ties, and numbers of living first-degree relatives. Cox models were used to evaluate associations, and a meta-analysis was used to determine whether effect estimates differed by cohort. Stratification by demographic, social, tumor, and treatment factors was performed.
Results: There were 1448 recurrences and 1521 deaths (990 due to BC). Associations were similar in 3 of 4 cohorts. After covariate adjustments, socially isolated women (small networks) had higher risks of recurrence (hazard ratio [HR], 1.43; 95% confidence interval [CI], 1.15-1.77), BC-specific mortality (HR, 1.64; 95% CI, 1.33-2.03), and total mortality (HR, 1.69; 95% CI, 1.43-1.99) than socially integrated women; associations were stronger in those with stage I/II cancer. In the fourth cohort, there were no significant associations with BC-specific outcomes. A lack of a spouse/partner (P = .02) and community ties (P = .04) predicted higher BC-specific mortality in older white women but not in other women. However, a lack of relatives (P = .02) and friendship ties (P = .01) predicted higher BC-specific mortality in nonwhite women only.
Conclusions: In a large pooled cohort, larger social networks were associated with better BC-specific and overall survival. Clinicians should assess social network information as a marker of prognosis because critical supports may differ with sociodemographic factors.
Candyce H Kroenke, Yvonne L Michael, Elizabeth M Poole, Marilyn L Kwan, Sarah Nechuta, Eric Leas, Bette J Caan, John Pierce, Xiao-Ou Shu, Ying Zheng, Wendy Y Chen