Donald Harrison – A Critical Analysis of the Value of Classification in Laryngeal Cancer

Written by David Howard

Donald Harrison commenced his 1974 Semon lecture with a brief history of laryngeal cancer over the previous 150 years, laying out the framework for the current classification and the desire of clinicians to divide cancer patients into various groups according to arbitrary stages. This had been initially based on simple clinical observations relating crude survival rates to the localisation of disease within the organ of origin and in relation to detectable regional or systemic metastases.

Unfortunately, as he pointed out in the lecture, the clinical oncologist by the 1970s was well aware that tumour growth was a reflection of a number of variables such as histological type, intrinsic growth rate and tumour host relationships. This meant that there would always be inherent weaknesses in any system classification that varied according mainly to anatomical site. He went on to describe how even in an organ such as the larynx, there are ill-defined and debatable anatomical sites. Evaluating the tumour with complete accuracy in the larynx often involved two-dimensional evaluation of a three-dimensional disease and whilst the TNM system of classification had been widely accepted as the standard method for reporting cancer it ignored the biological behaviour of the tumour. It did have the advantage of being widely used to allow some comparison of equivalent groups of patients. He pointed out that the TNM system was primarily dependent on the clinical expertise and integrity of the reporting clinician and was also controversial when individual institutions designed other systems of classification to suit their specific needs.

At the time of his lecture Harrison had carried out a comprehensive histological/pathological study with his friend, the pathologist Professor Leslie Michaels, of more than 150 whole organ serial sections of laryngectomy specimens between 1966 and 1973. This enabled him to compare errors in the clinical staging with prognosis and also carefully consider the significance of histological grading in relation to long-term cure. It was this type of detailed study and lifelong interest which gave him the ability to question the UICC system of classification for the larynx.

He went on to describe the difficulty of agreeing as to exactly what the dimensions of the vocal cord are and the significance of this definition in relation to the upper limits of the subglottic larynx and important factors such as the prognosis for subglottic extension of glottic carcinoma. Additionally, the difficulties of determining where the ventricle becomes the vocal cord and the saccule remains supra-glottis. These fine anatomical points were accompanied by a series of beautiful sections through the larynx showing cancers involving the vocal cord and the difficulties of determining the upper and lower limits.

He briefly covered the adequate assessment of the macroscopic extent of the neoplasm with the modern radiological techniques that were available at the time, such as contrast laryngography and tomography. It’s interesting to note that in 1974 he was doubtful if the newly proposed computerised axial tomography (CT scan) would offer additional information! He concluded this section of the lecture by stating that even using all modalities in the best centres there remained a discrepancy between clinical and radiological findings and the true extent of the tumour when examined after laryngectomy. He went on to briefly discuss the evaluation of regional and systemic metastases, describing the difficulties of the day in assessing whether lymph nodes contained tumour and the difficulty of knowing the true incidence of distant metastasis in laryngeal cancer, particularly as the number of autopsies being performed was declining even in the 1970s. Finally, he discussed the variability of histological grading and how its absence from any system classification seriously weakens the value and validity of the system. In conclusion, Sir Donald pointed out that all classifications are compromises, at best they encouraged careful recording of clinical and radiological impressions, but they were far from infallible and their obvious intrinsic weaknesses must be recognised and eventually overcome. Indeed, despite the tremendous advances in radiology and the moderate modern evaluation of malignancy we still do not have an excellent classification system.