1011 Background: Contralateral prophylactic mastectomy (CPM) use is increasing in women who are not at increased risk of contralateral cancer development and will experience no survival benefit from the more morbid procedure. Little is known about treatment decision-making or provider interactions. Methods: We surveyed patients newly diagnosed with breast cancer in 2013-14, identified through the population-based SEER registries of Los Angeles and Georgia, about 6 months after diagnosis, to determine receipt of diagnostic tests and factors related to the decision about surgery (including knowledge and perceived physician recommendation). Survey return is ongoing with an expected final response rate > 70%; current response rate 68%. Results: Nearly half of 1949 respondents with unilateral cancer considered CPM (20% very strongly, 6% strongly, 9% moderately, 10% weakly). Only 37% of those who considered CPM knew that it does not improve survival for all women with breast cancer (23% believed it does, 49% di...