A large cohort study found that larger social networks involving family, friends, community ties, and other connections were associated with better breast cancer–specific and overall survival.
“It is well established that larger social networks predict lower overall mortality in healthy populations and in breast cancer patients,” wrote study authors led by Candyce H. Kroenke, ScD, MPH, of Kaiser Permanente Northern California in Oakland. “However, associations with breast cancer–specific outcomes have been mixed.”
This study included 9,267 women in four cohorts from the After Breast Cancer Pooling Project. Researchers assessed social networks based on five components: spouse/intimate partner; number of relatives; friendship ties; religious/social ties; and community ties. The results of the analysis were published in Cancer.
Over a median follow-up period of 10.6 years, there were 1,448 recurrences and 1,521 deaths, 990 of which were due to breast cancer. Among three of the four study cohorts, survivors who qualified as “socially isolated” had an adjusted hazard ratio (HR) for recurrence of 1.43 compared with “socially integrated” patients (95% CI, 1.15–1.77; P for trend < .001).
The socially isolated women also had a higher risk of breast cancer–specific mortality, with an HR of 1.64 (95% CI, 1.33–2.03; P for trend < .001), and for total mortality, with an HR of 1.69 (95% CI, 1.43–1.99; P for trend < .001), compared with socially integrated women. These associations remained strong even after adjustment for lifestyle and treatment factors. The fourth cohort did not show significant associations.
Certain specific social characteristics were predictive of outcome. Being unmarried/unpartnered carried an HR for breast cancer–specific mortality of 1.37 (95% CI, 1.06–1.77), and an HR for total mortality of 1.45 (95% CI, 1.21–1.74), specifically in older white women. It was not linked to outcomes in younger women or in non-white women, however. Community ties, meanwhile, predicted lower risks of breast cancer–specific and total mortality in older white women and in Asian women, but not in others.
“Similar main effects associations in three cohorts, with subgroup differences as to which ties were most predictive, provide evidence that women depend differently on their social networks according to their demographic, cultural, and tumor characteristics,” the authors wrote. This suggests that a social network index may not be optimal for assessing social relationships’ effects on outcome in certain groups of patients.
“Healthcare providers need to assess information on social networks at the time of diagnosis and during follow-up because this may be a potential marker of prognosis,” the authors concluded.