This study found that of measures of QOL among breast cancer survivors at 6 months after diagnosis, greater social well-being was significantly associated with a decreased risk of mortality or recurrence. At 36 months postdiagnosis, however, no measures of QOL were associated with mortality or recurrence, although these analyses were based on a smaller sample size. The facets of social well-being at 6 months postdiagnosis that were most strongly inversely related with mortality or recurrence were those of marriage and family, social support, and interpersonal relationships.
Studies of QOL as a predictor of survival in cancer patients have generally found greater physical well-being to be associated with longer survival,5,26–28
although some of the more recent studies have found this association to be strongest or only among those in later stages of disease.6,11,13
These results suggest that the association may be a result of physical well-being serving as a proxy for physical health and/or the possibility of reverse causation. In our study, we found no association between physical well-being at 6 or 36 months postdiagnosis and survival when adjusting for clinical predictors, which supports this notion.
A recent review of studies of psychosocial factors and breast cancer outcomes14
found that the majority of studies (81%) observed a significant association between at least one psychosocial variable and disease outcome. Although the factors associated with survival were not consistent across many studies and the studies used different measurement techniques and had different follow-up times, factors associated with social support and marriage were most consistently associated with better prognosis. The association between social support and cancer progression was further analyzed in a 2009 review,18
which found that five of the seven methodologically sound papers that investigated the relationship with breast cancer observed strong evidence for an association with social support, interestingly, more for structural support (eg, the quantitative properties of the social network) than for functional support (eg, the qualitative aspects of the components of the structural support). A recent meta-analysis of studies of social networks and cancer mortality found that perceived social support, larger social network, and being married were associated with reductions in risk of 12% to 25%.16
This meta-analysis includes the report from the Nurses' Health Study,15
which found significant increases in risk for socially isolated women. Additionally, a recent study of breast cancer survivors in Washington, DC, found that, at 14 months postdiagnosis, both a confiding marriage or partnership and increasing numbers of nonhousehold supports were associated with a 59% to 69% decrease in risk of mortality.17
Contradicting those findings are the results of a larger study among young women with nonmetastatic breast cancer in Australia,12
which found no association between confidant or affective support at 11 months postdiagnosis and risk of recurrence or survival. The mechanism by which social support is associated with survival is not completely understood, but one possibility is provided by a recent study29
which found that mice in chronic social isolation compared with group-housed mice developed significantly larger mammary gland tumors and had heightened corticosterone stress responses.
Of course, we cannot rule out that these associations of social well-being and survival among breast cancer survivors are due to reverse causality. It is certainly possible that healthier individuals are more likely to have greater social well-being. However, we did adjust for all known clinical predictors, including stage, ER and PgR status, primary treatment, comorbidity at study enrollment, and whether a recurrence had taken place for the outcome of total mortality. Additionally, no associations were observed with psychological well-being, which one might assume would also be subject to the reverse causality problem. Another potential limitation of this study is the generalizability of the findings. The women who completed the follow-up questionnaire were older and of lower socioeconomic status than the breast cancer survivors who did not. Although we did not find an association with social well-being at 36 months postdiagnosis and survival, the impact of strong social well-being at 6 months postdiagnosis was not limited to immediate outcomes. When we excluded all follow-up and events happening within the first year after the QOL assessment (63 deaths and 30 recurrences), we found no change in the association between greater social well-being and lower risk of both mortality and recurrence.
Thus, the association between social well-being in the first year following diagnosis and breast cancer survival raises some interesting questions, because one's social well-being is potentially modifiable. Unfortunately, interventions to improve social well-being in breast cancer survivors have not generally been successful in prolonging survival,14,30
with two exceptions.31,32
More recently, a few interventions using online support groups have been successful in increasing breast cancer survivors' QOL33,34
; perhaps this is a potential avenue for future studies on social well-being intervention and breast cancer survival.
The findings of this study, which included a large number of women and had a high response rate, indicate that social well-being in the first year after diagnosis of breast cancer is significantly associated with mortality and recurrence, above and beyond known clinical predictors and self-assessed physical well-being. Should this association be replicated in future studies, the testing of a social well-being intervention for breast cancer survivors is warranted.