Histopathological assessment of tumour regression, nodal stage and status of resection margins determines prognosis in patients with oral squamous cell carcinoma treated with neoadjuvant radiochemotherapy

Abstract

Objectives: In advanced oral squamous cell carcinoma (OSCC), tumour regression after neoadjuvant radiochemotherapy seems to be an important prognostic factor. In this study, we intended to compare regression grading according to two previously described regression models and to analyse the association of tumour regression and other tumour characteristics with patients' characteristics and overall survival.

Methods: The retrospective study included 63 treatment-naive patients with primary OSCC of stages II-IV, who were treated with a concomitant neoadjuvant radiochemotherapy followed by radical surgery. Assessment of histopathological features was performed, there under regression grading according to two previously described regression models.

Results: Both tumour regression models provided comparable results in terms of distribution of different regression grades. In univariate analysis regression gradings (P = 0.003 and P = 0.007), ypT-stage, ypN-stage and status of resection margins (P < 0.001) were significantly associated with the 5-year overall survival (OS). None of the pretreatment clinicopathological parameters showed association with histopathological tumour regression. Multivariate analysis revealed the status of resection margins and of lymph node metastasis as statistically significant features for OS (P = 0.020 and P = 0.003, respectively).

Conclusion: Tumour regression grading, nodal stage and status of resection margins predict prognosis in patients after neoadjuvant treatment. Currently, there are no pretreatment clinicopathological parameters, which predicting good tumour response to therapy. Thus, identifying non-responding patients, which might benefit from an intensified systemic therapy, requires surgical resection and consecutive histopathological assessment. Therefore, further investigation and validation of new, especially, molecular predictors of tumour response to radiochemotherapy remains an unmet, future clinical need.

Keywords: histopathological assessment; neoadjuvant radiochemotherapy; oral squamous cell carcinoma; prognosis; regression grading.