Background: Durable progression-free survivors (dPFSors) over 2 years have been reported among melanoma patients treated with PD-1 blockade. However, non-negligible risk of further progression still exists and the optimal imaging surveillance interval is unknown. Methods: Individual patient data of progression-free survival (PFS) were extracted from PD-1 blockade clinical trials with follow-up of at least 5 years of PFS events. Co-treatment with anti-CTLA4 antibody was allowed. Patients with PFS of at least 2 years were considered as dPFSors. Conditional risk of progression or death with 95% CI was estimated based on a piece-wise exponential survival model, with the assumption that within each year from the beginning of the third year, the risk of progression/death (P/D) was constant. Conditional risks of P/D every 3, 4, 6, and 12 months in each subsequent year were calculated with 95% confidence interval (CI). We pre-specified three maximal risk levels – 10%, 15%, and 20% at each imaging scanning interval. An interval is considered as acceptable if the 95% CI upper bound of the risk at each scan is lower than a pre-specified risk level. Results: Of 1495 melanoma patients from 3 clinical trials, 474 (31.7%) were dPFSors. Among them, the PFS probability for additional 3 years was 76.4%. During the 3 years, no more than 5.0% of patients had P/D in any quarters. The yearly risk of P/D was 15.5% (95% CI 13.7% - 17.3%), 8.8% (6.8% - 10.8%), and 6.3% (3.8% - 8.8%) during the 3rd, 4th, and 5th year, respectively. Under risk at 10%, 15%, and 20%, melanoma dPFSors can be scanned every 6, 6, and 12 months during the 3rd year, every 6, 12, and 12 months during the 4th, and every 12, 12, and 12 months during the 5th, respectively. Conclusions: Based on their own risk tolerance level, our findings allow clinicians and dPFSors make data-driven decisions regarding imaging surveillance schedule beyond every 3 months.