In a large Kaiser Permanente study of women with invasive breast cancer, socially integrated women -- those with the most social ties, such as spouses, community ties, friendships and family members -- were shown to have significantly lower breast cancer death rates and disease recurrence than socially isolated women. This study was published in the American Cancer Society journal Cancer.

"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 Candyce H. Kroenke, ScD, MPH, 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 analyzed 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 characterized 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 percent more likely to have a recurrence of breast cancer

64 percent more likely to die from breast cancer

69 percent 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 percent 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 percent more likely to die of breast cancer than those with many friendship ties, and non-white women with fewer relatives were 33 percent 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.