  Electronic medical records (EMRs) are critical, highly sensitive private
information in healthcare, and need to be frequently shared among peers.
Blockchain provides a shared, immutable and transparent history of all the
transactions to build applications with trust, accountability and transparency.
This provides a unique opportunity to develop a secure and trustable EMR data
management and sharing system using blockchain. In this paper, we present our
perspectives on blockchain based healthcare data management, in particular, for
EMR data sharing between healthcare providers and for research studies. We
propose a framework on managing and sharing EMR data for cancer patient care.
In collaboration with Stony Brook University Hospital, we implemented our
framework in a prototype that ensures privacy, security, availability, and
fine-grained access control over EMR data. The proposed work can significantly
reduce the turnaround time for EMR sharing, improve decision making for medical
care, and reduce the overall cost
