What is the Natural History Study of Rare Solid Tumors?

What is the Natural History Study of Rare Solid Tumors?
The NIH Clinical Center (the research hospital of NIH) is open. For more details about its operating status, please visit cc.nih.gov.
Updates regarding government operating status and resumption of normal operations can be found at opm.gov.
What is the Natural History Study of Rare Solid Tumors?