The Gerontologist Published by Oxford University Press on behalf of The Gerontological Society of America 2009. doi:10.1093/geront/gnp048 1

Purpose: This study evaluates the changes in so-cial networks of older and younger breast cancer patients over a 6-month period following their fi rst diagnosis and how such modifi cations are associat-ed with changes in the patients ’ mood state. De-sign and Methods: Newly diagnosed breast cancer patients were interviewed shortly after their diagnosis and again 6 months later. Female support network members enumerated by patients were inter-viewed once within 3 months of the patients ’ initial interview. Results: Findings based on informa-tion for 149 network members of 26 patients indicate that members in older ( ≥ 51 years) patients ’ networks were less likely to be dropped at follow-up (odds ra-tio [OR] = 0.21, p =.04) compared with those in younger patients ’ networks. Network members who provided more support were less likely to be dropped by younger patients (OR = 0.42, p <.01). Decrease in network size was associated with decrease in mood disturbances among younger patients (Profi le of Mood State–Bipolar: b = 0. 35, p ≤.01). Impli-cations: Reducing the number of network mem-bers after cancer diagnosis may not necessarily lead to psychological distress, providing support for self-regulation of social network resources among cancer patients. Older patients ’ network members were more embedded in patients ’ networks, making it more stable over time. Identifying important network members (e.g., frequent support providers for younger patients and family members for older patients) and facilitating positive social interactions between these network members and patients may be benefi cial