OBJECTIVES: The utilization of healthcare services and costs among cancer patients are often estimated by the phase of care: initial, interim and terminal. While their durations are often set arbitrarily, we sought to establish data-driven phases of care in an advanced melanoma population using joinpoint regression. METHODS: A retrospective claims database study was conducted to assess the costs of advanced melanoma from diagnosis of distant metastases to death during 01/2010-09/2014. Joinpoint regression analysis was applied to identify the best-fitting points where statistically significant changes in the trend of monthly costs occurred. To identify the initial phase, average monthly costs were modeled from metastases diagnosis to death and to identify the terminal period, costs were modeled backward from death to metastases diagnosis. Points of inflection of the monthly cost trend denoted the ending and starting points respectively. The months in between represented the treatment phase. RESULTS: A total of 1,671 advanced melanoma patients who died (757 stage IIIC and 914 stage IV) met the eligibility criteria. The initial phase was identified as the 5-month period from advanced diagnosis following which there was a significant and sharp decline in  monthly cost trend (Monthly percent change (MPC) = -13.0%; 95% CI -16.9% to -8.8%). Similarly, the terminal phase was defined as the 5-month period prior to death (MPC = -14.0%; 95% CI -17.6% to -10.2%). CONCLUSIONS: In this metastatic melanoma population, the optimal duration of the initial and terminal phases of care was 5 months immediately after diagnosis and prior to death, respectively. Combined with clinical judgment, joinpoint regression provided data-supported phase of cancer care durations for the reporting of costs from metastases diagnosis to death.