High preoperative carcinoembryonic antigen (CEA) levels are associated with recurrence after colon cancer resection, and its value is growing such that some even think it should be incorporated into staging. But what’s the best way to measure something as fluid as the CEA? A novel analysis from MSKCC asks: do CEA levels matter more before or after surgery? As we would have guessed, elevated preop CEA levels were associated with a 7% reduction in recurrence-free survival (RFS) across the board at 3 years. But! A postoperative normalization of CEA level essentially negated the prognostic value of an elevated preop level, while patients with continued elevated postop CEA levels had a nearly 15% reduction in RFS. In these patients, the hazard for recurrence increased rapidly postop and peaked at 12 months out, suggesting that they may benefit from more aggressive adjuvant therapy. Whatever your feelings on climate regulations for 2018, rising CEA levels--at least ones occurring after colon cancer resections--should probably be taken seriously.