OBJECTIVES: The National Cancer Institute (NCI) estimates that cancer accounted for approximately $124.57 billion dollars in direct costs in the United States in 2010.  NCI provides costs estimates on the initial, continuing and last ‘phase of care’ but does not provide a breakdown by stage.  This study aims to describe the costs associated with stage 3 (S3) and stage 4 (S4) colon cancer (CC).  METHODS: Data from 1997-2005 of the Surveillance, Epidemiology, and End-Result-Medicare dataset was used for this analysis.  Individuals included were those diagnosed as having AJCC S3 or S4 CC.  Analyses excluded individuals who were not eligible for Medicare Parts A and B or those insured by Medicare HMO.  Areas under the curve (AUC) for direct medical costs were summed over a 40 week period, from time of CC diagnosis.  Costs contributed were from beneficiaries who died from S3 and S4 CC and were ever treated with chemotherapy. Costs were summed for S3 and S4 individuals with at least 26 weeks of initial chemotherapy treatment.  RESULTS: These analyses identified 3549 individuals with S3 CC and 8194 individuals with S4 CC.  Over the 40 week observation period, the AUC for S3 and S4 CC was $52,145, and $45,106, respectively. Mean weekly costs peaked at week 31 for S3 CC ($3425) and at week 29 for S4 CC ($1,725). Among S3 and S4 individuals with at least 26 weeks of initial chemotherapy treatment, the AUC was $35,890 for S3 CC and $49,871 for S4 CC.   CONCLUSIONS: Among individuals who died with S3 or S4 CC and were ever treated with chemotherapy, the costs associated with S3 cancer exceed those of S4 cancer over the 40 week observation period. Among those with at least 26 weeks of initial chemotherapy and treatment, S3 chemotherapy treatment is less expensive than S4 chemotherapy treatment.