Abstract Background. Sentinel lymph node biopsy (SLNB) with 2 mL of superparamagnetic iron oxide (SPIO) tracer has shown to be non-inferior to the standard radioisotope technique in several studies. The SUNrISE randomized trial has shown non inferiority of 1mL vs. 1.5 mL vs. 2 mL dose of SPIO with the standard use of radioisotope 99m Tc. We present patient reported outcomes from this randomized trial. Material and methods. Patients with stage I breast cancer who underwent breast conservative surgery and sentinel lymph node biopsy were assigned consecutively (1:1:1) to one of the three groups defined by the different SPIO dose, group 1 (1mL), group 2 (1.5 mL) and group 3 (2 mL). Patients filled a questionnaire related to the presence of skin staining, staining intensity ( mild, moderate, intense) and whether the stain worried them. Patient also completed a quality of life (QoL) EORTC C30 questionnaire at 1 month postoperative visit, at 6 months and at 12 months. First analysis from the 1 month postoperative outcomes are reported here. Follow up on the 6 months will be available for the meeting. Results. One hundred and thirty five patients were included in the trial, 45 in each group. Median age in group 1 was 58 years old, 63 y/o in group 2 and 65 y/o in group 3. (p=0.03) At 1 month follow up, patients in group 1 had less skin tattoo when compared with patients in group 2 and 3 (p= 0.02). There were no significant differences related to skin staining intensity by doses. Seventy percent of patients felt no concern about the tattoo. On the multivariate analysis including age, SPIO dose, body mass index and breast density, only younger age (p = 0.037), and higher SPIO doses (p= 0.029) were significantly associated with increased skin staining. There were no statistically significant differences in responses in the QoL questionnaire at 1 month postoperative visit. There were no severe reactions to the procedure or complications in any patient. Conclusions. SLN with 1mL dose of SPIO has shown non-inferiority in the detection of SLN when compared to 1.5 and 2 mL. Being young and the use of 1.5 and 2 mL increased the risk of developing skin staining. Even though, most of the patients were not concern about the skin staining. Rates of discontinuation of skin discoloration will be assessed at 6 months follow up. Citation Format: Rubio IT, Esgueva A, Espinosa-Bravo M, Rodriguez-Revuelto R, Siso C, Rivero J. Patient reported outcomes in women undergoing sentinel lymph node biopsy in the SUNrISE randomized trial evaluating different doses of superparamagnetic iron oxide [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-03-15.