Can the new American Joint Committee on Cancer staging system predict survival in rectal cancer patients treated with curative surgery following preoperative chemoradiotherapy?

Background: Although ypStage has been known as a strong prognosticator of recurrence and survival, the detailed interaction of ypT and ypN classification on a survival rate has never been evaluated.

Methods: Between October 2001 and December 2007, in total, 960 patients with locally advanced rectal cancer were enrolled retrospectively at 3 centers. Five-year overall survival (OS) and disease-free survival (DFS) rate were calculated for each ypTN classification.

Results: The ypT classification interacted with ypN classification to affect survival in most categories. Patients with ypStage 0 and I cancers showed a >90% 5-year OS (ypStage 0, 96.5%; ypStage I, 92.9%; P = .346) and 5-year DFS (ypStage 0, 90.2%; ypStage I, 90.7%; P = .879). Among ypStage III subgroups, large differences in 5-year OS (ypStage IIIA, 90.1%; ypStage IIIB, 68.3%; ypStage IIIC, 40.5%; P < .001) and 5-year DFS (ypStage IIIA, 74.8%; ypStage IIIB, 55.1%; ypStage IIIC, 12.3%; P < .001) were observed. OS and DFS in patients with ypStage IIIA disease were similar to or greater than those in patients with ypStage IIA or IIB/IIC disease. Four patient risk groups were defined: 1) low (ypT0-isN0, ypT1N0, ypT2N0), 2) intermediate (ypT0-2N1, ypT3N0), 3) moderately high (ypT0-2N2, ypT3N1, ypT4N0), and 4) high risk (ypT3N2, ypT4N1-2). Risk grouping showed a narrower range of survival rate compared with ypStage grouping.

Conclusions: ypStage in rectal cancer, defined according to the 7th edition of the American Joint Committee on Cancer staging system, predicts survival for most ypNT classifications. However, patients with ypStage I rectal cancer have a similar prognosis to those with ypStage 0 cancer, and risk grouping reflects more precise survival outcomes than ypStage.