Tumor thickness versus depth of invasion - Analysis of the 8th edition American Joint Committee on Cancer Staging for oral cancer

Oral Oncol. 2017 Nov;74:30-33. doi: 10.1016/j.oraloncology.2017.09.007. Epub 2017 Sep 19.


Objectives: The primary aim of this study is to compare the effect of using tumor thickness versus depth of invasion (DOI) to determine the 8th edition AJCC T-category on survival in a large cohort of OSCC.

Materials and methods: A retrospective cohort study of patients whose clinicopathologic information had been collected prospectively into a dedicated head and neck database. 927 patients with oral SCC were identified in this cohort, with the final study population including 456 patients with complete information on DOI, tumor thickness, T and N staging and follow-up.

Results: 26 (5.7%) patients had a different AJCC 8 T category when using thickness instead of depth. 15 were upstaged from T1 to T2, 10 upstaged from T2 to T3 and 1 down staged from T2 to T1. Additionally, similar stratification of disease-specific and overall survival curves were found for T category based on DOI and thickness.

Conclusion: The T category and TNM stage prognostic performance of 8th edition AJCC staging of oral cancer is similar regardless of whether DOI or thickness is used as the T-category modifier. In centers without complete DOI data it is reasonable to impute thickness for retrospective survival analyses using the 8th edition of the AJCC staging system.

Keywords: AJCC 8; Depth of invasion (DOI); Disease-specific survival; Oral SCC; Overall survival; Staging; T category; Thickness.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Carcinoma, Squamous Cell / pathology*
  • Carcinoma, Squamous Cell / therapy
  • Female
  • Humans
  • Male
  • Middle Aged
  • Mouth Neoplasms / pathology*
  • Mouth Neoplasms / therapy
  • Neoplasm Invasiveness*
  • Neoplasm Staging
  • Prognosis
  • Retrospective Studies
  • Survival Analysis
  • Young Adult