Introduction: Increasing numbers of cancer survivors and the recognition of their needs beyond recurrence surveillance are stretching resources at many cancer centers. Sometimes, patients solely follow up with providers other than the oncologist without coordinated care transfer plans. This study examines factors associated with transfer of breast cancer survivorship care outside one large cancer center. Methods: Records on women with breast cancer diagnosed between July 1, 1997 and March 31, 2010 were linked to billing data through March 31, 2012 to identify the details of last oncology follow-up. A patient was classified as having transferred care outside the center if there was no oncology visit for more than 2 years. Clinical and pathologic characteristics were examined in a multivariate proportional hazards model to identify factors associated with transfer of care. Results: Of 3,924 women with breast cancer, 858 (21.9 %) transferred care outside of our institution, 18 and 36 % at 5 and 10 years, respectively. Factors independently associated with transfer of care were age at diagnosis (unit increase 1.01/year age), stage IIA (HR 1.30, p = 0.02), longer driving distance to the cancer center (HR 1.65, p < 0.01), having had a cancer recurrence (HR 0.15 p < 0.01), and last visit in a medical oncology versus surgical oncology clinic (HR 0.32 p < 0.01). Conclusions: Many patients with breast cancer do not continue oncology follow-up after treatment. Cancer programs should develop mechanisms to assist patients with care transfer and assure coordinated transfer to other providers to improve continuity of care. Implications for Cancer Survivors: The results of this study will help the cancer centers identify the population of patients that are most likely to transfer care or become lost to follow up. Prospectively, identifying patients who may be more likely to transfer care will offer opportunities to effectively coordinate posttreatment surveillance with primary care. © 2013 Springer Science+Business Media New York.