Lead author Candyce H. Kroenke, a research scientist with the Kaiser Permanente Northern California Division of Research, said the study involved 2,264 women who were diagnosed with early-stage, invasive breast cancer from 1997 to 2000.
After providing information on their personal relationships, the women were characterized as socially isolated with few ties, moderately integrated, or socially integrated with many ties.
Previous research has shown women with larger social networks -- including spouses or partners, female relatives, friends, religious and social ties, and ties to the community through volunteering -- have better breast cancer survival outcomes.
The study, published in the Breast Cancer Research and Treatment, found socially isolated women were 34 percent more likely than socially integrated women to die from breast cancer or other causes.
Larger social networks were "unrelated to recurrence or breast cancer mortality, [but] they were associated with lower mortality from all causes," the authors wrote in the study.
"Women with small networks and high levels of support were not at greater risk than those with large networks, but those with small networks and low levels of support were," Kroenke said.
Women with small networks and low levels of support were 61 percent more likely to die from breast cancer and other causes than those with small networks and high levels of support, Kroenke said.