The AJCC cancer staging manual was updated in 2017 (8th edition). It is used in the MDT setting for planning treatment and assessing prognosis for individual patients, and is also widely used internationally in clinical trials. Unlike previous iterations of the AJCC dating back to 1988, there have been very significant changes in this edition, specifically for HPV-associated oropharyngeal cancer (OPC). The clinical implications of these changes in both T, N and overall staging is that modifications often result in downstaging, i.e. patients previously categorised as stages III-IV will now be reclassified as stages I-II. This large-scale validation study using the US National Cancer DataBase retroactively restaged 15,116 patients with HPV-positive OPC according to the 8th edition AJCC manual, excluding patients with unknown or negative HPV status, unknown staging or survival duration. Median follow-up was 29.1 months. Comparisons using the 7th edition downstaged 93.9% of patients clinically, and 91.7% pathologically.
Survival discrimination between clinical and pathological stage groups was significantly different using the eighth edition, unlike the poor survival discrimination between groups in the seventh edition. Comparison analysis revealed a large increase in the proportion of early-stage disease (0-II) of 10.3% to 84.5% and a corresponding decline in stage III-IV disease of 89.7% to 15.5%.
The authors acknowledge that more work now needs to be done on translating the effect of the new staging manual on de-escalation of treatment in HPV-positive OPC and using the new edition in future trials will be central to this.
