PURPOSE:To improve care coordination for complex cancers, it is critical to establish a more nuanced understanding of the types of providers involved. As the number of provider types increases, strategies to support cancer care coordination must adapt to a greater variety of information needs, communication styles, and treatment strategies. METHODS:We categorized providers into 11 types, using National Provider Identifier specialties. Using Medicare claims, we counted the number of unique combinations of provider types billed during preoperative, operative, and postdischarge care for colon cancer surgery and assessed how this count varies across hospitals. The study included 70,567 beneficiaries in fee-for-service Medicare A and B for 6 months before and 60 days after an admission for colectomy for colon cancer between 2008 and 2011. RESULTS:We observed 1,554 preoperative provider-type combinations, 975 operative combinations, and 1,571 postdischarge combinations. The three most common combinations in the preoperative phase were general medicine only, other medical specialists only, and general medicine and other medical specialists. In the operative phase, the three most common combinations were primary surgery, anesthesiology, and pathology; general medicine, other medical specialists, radiology, primary surgery, anesthesiology, and pathology; and other medical specialists, radiology, primary surgery, anesthesiology, and pathology. In the postdischarge phase, the three most common combinations were general medicine, general medicine and other medical specialists, and general medicine and oncology. On average, each hospital had 15 preoperative, 11 operative, and 15 postoperative combinations. High-volume, larger, teaching, urban, and noncritical access hospitals had more combinations in all phases. CONCLUSION:Many provider-type combinations are involved in colon cancer surgery care. Substantial variation exists across hospitals types, suggesting that certain hospitals need additional resources and more flexible infrastructure to coordinate care.