Do I have to share my information with the government while on a clinical trial?

Many clinical trials are designed and managed by the National Cancer Institue (NCI) in the United States. This is a government funded agency whose goal is to improve cancer care. Data from many clinical trials are collected and stored within the NCI or aligned agencies, however, it is typically de-identified such that patients are protected from even the tiniest possible overreach of the government. The data collected and managed is solely used for improving cancer care.