A comprehensive cancer center is an institution that has been designated by the National Cancer Institute (NCI) as a center of excellence for cancer care and research. Institutions have to apply for designation as a comprehensive cancer center and renew their status every three to five years. According to the NCI, there's no difference in the quality of care provided by NCI-designated "cancer centers" versus NCI-designated "comprehensive cancer centers."
The NCI uses the term "comprehensive" to indicate an institution offers state-of-the-art care and services that include a strong research base along with a variety of prevention, care, and educational activities that serve the community. The NCI provides a list of comprehensive cancer centers on its website.
Sources:
"Cancer Centers Program: Cancer Centers List." National Cancer Institute. Accessed 5 Mar. 2008 [http://cancercenters.cancer.gov/cancer_centers/cancer-centers-names.html].
"Cancer Centers Program: Our History." National Cancer Institute. Accessed 5 Mar. 2008 [http://cancercenters.cancer.gov/about/our-history.html].
"NCI-designated Cancer Centers." National Cancer Institute. Accessed 5 Mar. 2008 [https://cissecure.nci.nih.gov/factsheet/FactsheetSearch.aspx?FSType=1.2].

