Relative prognostic value of TNM7 vs TNM6 in staging oesophageal cancer

BACKGROUND: Stage migration consequent upon new cancer staging definitions may result in artifactual alterations in stage-specific survival and prognosis. The aim of this study was to determine the influence of the new TNM7 oesophageal cancer (OC) system on stage categorisation and survival when compared with historical controls. METHODS: A total of 202 patients diagnosed with operable OC and undergoing oesophagectomy (118 neoadjuvant chemotherapy) were studied. Patients originally classified and staged using TNM6 were retrospectively re-staged using TNM7. RESULTS: Re-classification of TNM7 resulted in stage migration in 11.9% of patients (9.9% downstaged, 2.0% upstaged) when compared with TNM6. Five-year survival for stages I, II and III was 78%, 46% and 18% using TNM6, compared with 62%, 51% and 18%, respectively, using TNM7. Univariable analysis revealed that histological grade (P=0.006), pT (P<0.0001), TNM6 pN (P<0.0001), TNM7 pN (P<0.0001), number of lymph node metastases (P<0.0001), TNM6 stage group (P<0.0001), TNM7 stage group (P<0.0001) and TNM7 prognostic group (P<0.0001) were all associated with survival. Multivariable analysis revealed that only the TNM7 prognostic group was independently and significantly associated with survival. CONCLUSION: TNM7 is a better prognostic tool than TNM6 and represents an important advance in staging OC.