Importance of tumour thickness measurement in prognosis of tongue cancer

Abstract

Eighty-one patients who underwent surgery for cancer of the tongue were retrospectively studied to evaluate the influence on survival of some clinical and pathologic parameters. These parameters and data on the patient's current status were gathered by the study of tissue sections, using haematoxylin-eosin staining, and from medical records. The 5-year survival rate was 68.5%. Univariate analysis showed that the parameters influencing survival were: T (P<0.01), pathologic T (P<0.01), N (P<0.05), pathologic N (P<0.05), extracapsular nodal spread (P<0.05), locoregional recurrence (P<0.01), and tumour thickness (P<0.05). Multivariate analysis showed that tumour thickness had the greatest influence on survival. Patients with tumour thickness of ⩽3 mm had a 5-year survival of 85.7%, significantly greater (P<0.05) than the rates of 58.3 and 57% for patients with tumour thickness of 4–7 mm and >7 mm, respectively. Wider studies are required to unify criteria for the measurement of this important prognostic parameter.

Introduction

The prognostic value of the TNM system has been widely reported as inadequate in patients with oral squamous cell carcinoma (OSCC) [1], [2], [3]. Among the parameters that make up the TNM system, the maximum superficial diameter (T) is especially controversial [4] for several reasons: (a) the clinical measurement of tumours in the upper aerodigestive tracts can be difficult; (b) the size of tumours is not necessarily related to the prognosis, so that some large tumours progress satisfactorily, whereas some small tumours can kill the patient despite treatment; (c) most oral and pharyngeal SCC are T2 with superficial diameters ranging from 20 to 40 mm, and it seems unlikely that tumours so varied in size could have the same prognosis [5]; and (d) some carcinomas of the aerodigestive tracts are multicentric, complicating further the measurement of the superficial diameter.

Attempts have been made to improve the measurement of the tumour size, in order to increase its value as a predictive prognostic factor in OSCC. Measurement of the maximum diameter of the tumour on the operative specimen (pathologic T) has been proposed [6], whereas other studies [4], [7], [8], [9], [10], [11] have focused on the predictive value for OSCC of the tumour thickness considered alone. The aim of the present work was to compare the prognostic value of widely used clinical and pathologic parameters such as N, M, extracapsular nodal spread, and tumour size, measured as maximum superficial diameter (T), maximum diameter of operative specimen (pathologic T), and tumour thickness, in a retrospective study of patients with cancer of the tongue, an OSCC site associated with an especially poor prognosis [12].