ypN0: Does It Matter How You Get There? Nodal Downstaging in Esophageal Cancer.

Background: ypN0 following induction treatment for advanced esophageal cancer improves survival. Importance of how ypN0 is achieved is unknown. This study evaluates survival in "natural" N0 (cN0/ypN0) and "downstaged" N0 (cN+/ypN0) patients.

Methods: Among patients treated with induction treatment and surgery, 83 CT scans were retrieved in digital format and re-evaluated by a radiologist, blinded to pathological nodal status: 28 natural N0, 37 downstaged N0, and 18 ypN+. Impact of N0 classification on survival and associations with survival were identified.

Results: Survival varied with ypN: 3-year survival was 84 % for natural N0 patients, 59 % for downstaged N0, and 20 % for ypN+ (p < .001). Compared with natural N0 patients, risk of cancer mortality was 3.8 for downstaged N0 and 7.6 for ypN+ (p = .01). Survival was also stratified by ypT: compared with ypT0 natural N0, who had the best survival, intermediate survival was seen in ypT+ natural N0 [hazard ratio (HR), 1.3] and ypT0 downstaged N0 (HR, 1.8), and poor survival in ypT+ downstaged N0 (HR, 9.5) and ypN+ (HR, 12.0) (p = .026).

Conclusions: Natural N0 and downstaged N0 patients are different clinical entities: downstaging cN+ with induction treatment producing downstaged N0 improves survival only if there is concomitant primary cancer downstaging to ypT0. Intermediate survival is seen in downstaged N0 patients with complete tumor response. Natural N0 patients experience intermediate survival with incomplete response (ypT+). Complete response in natural N0 patients produces the best survival. Means of obtaining ypN0 status matters and requires a complete response for downstaged N0 patients to benefit from induction treatment.