External validation of the AJCC Cancer Staging Manual, 8th edition, in an independent cohort of oral cancer patients Leandro Luongo Matos a,⇑ , Rogerio Aparecido Dedivitis b , Marco Aurélio Vamondes Kulcsar c , Evandro Sobroza de Mello d , Venâncio Avancini F. Alves e , Claudio Roberto Cernea f a Department of Head and Neck Surgery, University of Sao Paulo Medical School (LIM 28); Attending Surgeon, Instituto do Câncer do Estado de São Paulo (ICESP), Brazil b Department of Head and Neck Surgery of Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, Brazil c Department of Head and Neck Surgery, University of Sao Paulo Medical School; Chairman, Instituto do Câncer do Estado de São Paulo (ICESP), Brazil d Pathology Department, University of Sao Paulo Medical School; Attending Pathologist, Instituto do Câncer do Estado de São Paulo (ICESP), Brazil e Head of Division of Pathology Department, University of Sao Paulo Medical School, Brazil f Head of Division of the Department of Head and Neck Surgery of Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, Brazil article info Article history: Received 20 February 2017 Received in revised form 22 May 2017 Accepted 27 May 2017 Keywords: Mouth Mouth neoplasms Lymphatic metastasis Neoplasm staging Recurrence Survival abstract Objectives: To evaluate the new American Joint Committee on Cancer (AJCC) cancer staging manual (8th edition) in an independent cohort of patients surgically treated for oral squamous cell carcinoma in order to determine whether the upstaging of pT and pN classification was indicative of a worse prognosis. Methods: A cohort of 298 patients was analyzed retrospectively. Results: Of these patients, 22.8% received an upstaging when the depth of invasion was included into the pT classification. Similarly, 29.2% of them were upstaged when extracapsular extension was added to pN classification. Twenty-eight of 68 patients (41.2%) that received an upstaging of pT classification died, and 23 (33.8%) experienced disease recur- rence compared to 98/229 (42.8%) and 68/229 (29.7%), respectively, for those with the same pT during follow-up. With regard to pN classification, 70.6% of upstaged patients (60/85) died, and 50.6% (43/85) developed recurrence of the disease compared to 63/205 (30.7%) and 42/205 (20.5%), respectively, for those with the same pN during follow-up. Patients who were upstaged in pT classification presented a worse DFS (51.1% versus 80.4%, P = 0.007) and OS (31.5% versus 58.6%, P = 0.017). Similarly, those that were upstaged in pN classification presented a worse DFS (17.1% versus 61.2%, P = 0.001) and OS (8.5% versus 37.9%, P < 0.001). Conclusion: The new AJCC cancer staging manual (8th edition) allows a better stratification of oral SCC patients. By including the depth of invasion to the pT classification and extran- odal extension to the pN classification, a worse disease-free and overall survival was assessed for these patients. Ó 2017 Elsevier Ltd. All rights reserved. Introduction In the Fall of 2016, the American Joint Committee on Cancer (AJCC) published the 8th edition of the Cancer Staging Manual. Important changes included adding the depth of invasion (DOI) and extranodal extension (ENE) to the pT and pN classification sys- tems, respectively. Patients with tumors of 2 cm or less in greatest dimension and DOI of 5 mm or less are staged as pT1, those with tumors of 2 cm or less and DOI between 5 and 10 mm or with tumors greater than 2 cm but not more than 4 cm in greatest dimension and DOI no more than 10 mm are classified as pT2, and individuals with tumors greater than 4 cm or DOI greater than 10 mm are grouped as pT3. Patients with ENE are staged as pN2a if a single node less than 3 cm in diameter is present, and all other patients are staged as pN3b [1]. A recent publication by Lydiatt et al. [2] has validated the pT classification changes in 1792 patients at Memorial Sloan Kettering Cancer Center (New York, USA) and Princess Margaret Hospital (Toronto, Canada). The pN classification was studied using the records of the National Cancer Database (NCDB) and validated with the data of both institutions. According to the new staging system for both pT and pN classifications, a worse five-year overall sur- vival was demonstrated in these patients. This study was used as a reference for AJCC stage group analysis. The aim of the present study was to evaluate the new AJCC clas- sification in an independent cohort of surgically treated oral SCC patients in order to provide an external validation as to whether http://dx.doi.org/10.1016/j.oraloncology.2017.05.020 1368-8375/Ó 2017 Elsevier Ltd. All rights reserved. ⇑ Corresponding author at: Av. Dr. Enéas de Carvalho Aguiar, 255 – 8th floor – room 8174, 05403-000 São Paulo, SP, Brazil. E-mail address: l.matos@fm.usp.br (L.L. Matos). Oral Oncology 71 (2017) 47–53 Contents lists available at ScienceDirect Oral Oncology journal homepage: www.elsevier.com/locate/oraloncology