Childhood Cancer Survivorship, Treatment, Access, and Research Act of 2017 or the Childhood Cancer STAR Act This bill amends the Public Health Service Act to authorize the National Institutes of Health (NIH) to provide support to collect the medical specimens and information of children, adolescents, and young adults with selected cancers that have the least effective treatments in order to achieve a better understanding of these cancers and the effects of treatment. The national childhood cancer registry is reauthorized through FY2022 and revised to authorize the Centers for Disease Control and Prevention to award grants to state cancer registries to improve tracking of childhood cancers. The Department of Health and Human Services (HHS) may: (1) support pilot programs to develop or study models for monitoring and caring for childhood cancer survivors throughout their lives, (2) establish a task force to develop and test standards for high-quality childhood cancer survivorship care, and (3) carry out a demonstration project to improve care coordination as childhood cancer survivors transition to adult care. HHS must convene a Workforce Development Collaborative on Medical and Psychosocial Care for Pediatric Cancer Survivors. The NIH may support research on: (1) outcomes for, and barriers faced by, pediatric cancer survivors within minority or medically underserved populations; and (2) follow-up care for pediatric cancer survivors, including research on the late effects of cancer treatment and long-term complications. The Government Accountability Office must make recommendations to address barriers to childhood cancer survivors obtaining and paying for adequate medical care.