Contribution of care source to cancer treatment cost variation in the US military health system

The US Military Health System (MHS) provides universal access to health care for more than nine million eligible beneficiaries through direct care in military treatment facilities or purchased care in civilian facilities. Using information from linked cancer registry and administrative databases, we examined how care source contributed to cancer treatment cost variation in the MHS for patients ages 18-64 who were diagnosed with colon, female breast, or prostate cancer in the period 2003-14. After accounting for patient, tumor, and treatment characteristics, we found the independent contribution of care source to total variation in cost to be 8 percent, 12 percent, and 2 percent for colon, breast, and prostate cancer treatment, respectively. About 20- 50 percent of the total cost variance remained unexplained and may be related to organizational and administrative factors.