Comparison of AJCC 7th and 8th edition staging system in oral squamous cell carcinoma: A retrospective study

Objectives: The American Joint Committee on Cancer (AJCC) proposed staging system in order to stratify patients with oral cancer. The tumor-nodal-metastasis (TNM) classification is widely used to plan treatment and to estimate the prognosis of patients. The 8th edition staging system incorporated two major prognostic factors; depth of invasion (DOI) and extra-nodal extension (ENE). This study was done to evaluate and assess the difference in staging of AJCC 8th edition oral squamous cancer carcinoma (OSCC) when compared with AJCC 7th edition and to understand the pattern of stage migration due to these modifications. Materials and methods: Patients operated for OSCC with histopathology reports staged according to AJCC 8th edition were included in this single center, retrospective study between 2019 and 2022. Results: Out of total 200 patients, 9 cases were upstaged on the basis of DOI. 2 cases underwent stage migration from stage I to stage II, 4 cases from stage II to stage III, 2 cases from stage III to IV and 1 case underwent stage migration from II to IV. Likewise, 31 cases were upstaged on the basis of ENE and underwent upstaging from stage IVa to stage IVb. Conclusion: The AJCC 8th edition upstaged a total of 31% of patients with oral cavity cancers. 4.5% cases were upstaged on the basis of DOI. 26.5% patients were upstaged on the basis of presence of ENE. To conclude, the new classification has enabled us to adequately manage patients who were previously under-staged and under-treated.