Introduction Studies suggest that social support is associated with improved health outcomes in cancer patients. The relationship between social environmental and health outcomes in elderly Brazilian women with breast cancer has not been investigated. This study aimed to explore the association between social support prior to treatment in a reference centre in Brazil and quality of life (QOL) in elderly women and women under 60 years of age with breast cancer.

Methods This study included women with breast cancer who started oncology treatment at National Cancer Institute between June 2009 and March 2010. The Medical Outcomes Study—Social Support Survey was used to assess social support prior to treatment. EORTC QLQ-C30 and BR23 module were used to measure QOL. Bivariate analyses of dichotomous variables and independent variables were carried out and RRs with CIs of 95% presented.

Results 195 women were examined of whom 46.2% (90) were elderly. Older women who reported good emotional support had lower risk of presenting the worst score of global health (RR 0.69 (95% CI 0.55 to 0.88)), functionality (RR 0.59 (0.38 to 0.91)) and symptoms (RR 0.25 (0.10 to 0.60)) of C30 questionnaire. Emotional support was negatively associated with global health in women aged under 60 years (RR 0.65 (0.50 to 0.85)).

Conclusions In this population social environment is positively associated with QOL; this effect is greatest in elderly women.