Background: Fractional CO2 laser therapy is an emerging treatment for GSM. The objective of this study was to determine the feasibility, tolerability and preliminary efficacy of fractional CO2 laser therapy in BC survivors. Methods: This was a single arm feasibility study of BC survivors with dyspareunia and/or vaginal dryness. Participants received three treatments with office-based fractional CO2 laser on at least 30 day intervals and returned for a one-month follow-up. Feasibility was defined as treatment completion without serious adverse events (SAE) in a minimum of 80% of patients. Primary efficacy was evaluated using the mean change (∆) in the score on the Vaginal Assessment Scale (VAS). Secondary efficacy endpoints included mean ∆ in scores on the Female Sexual Function Index (FSFI) and Urogenital Distress Inventory (UDI). Descriptive statistics (means and 95% confidence intervals (CI) for continuous variables and proportions for categorical variables) were used. Results: The study is ongoing with 65 patients enrolled. To date, 37 patients have completed all study treatments and follow-up. Median age for those who have completed treatment was 57 years (range 34-72). Most were ER/PR positive (78%) and Her 2 negative (81%) with stage I (43%) or II (41%) BC. Ninety-five percent were receiving endocrine therapy, most commonly aromatase inhibitors (73%). No SAEs were reported in the 37 patients who have completed study treatments and their outcomes are as follows. Based on the VAS, 78% reported moderate-severe dyspareunia and 89% reported moderate-severe vaginal dryness at baseline. At follow up, 28% reported moderate-severe dyspareunia and 28% reported moderate-severe vaginal dryness. The VAS score improved from baseline to follow up (mean ∆ 4.1; 95% CI [3.1, 5.1]). Similarly, the FSFI score improved (mean ∆ -10.0; 95% CI [-13.2, -6.9]) and the UDI score improved (mean ∆ -5.7; 95% CI [-10.1, -1.3]). Final efficacy analysis will be reported once all patients have completed all time points. Conclusions: Fractional CO2 laser treatment is feasible and tolerable in BC survivors and may reduce symptom burden from GSM. A randomized controlled trial with sham laser is currently in development. Clinical trial information: NCT03307044