What is the earliest non-invasive malignant lesion of the larynx?

Accessible online at: www.karger.com/journals/orl Cancer of the larynx constitutes 1–2% of all malignancies diagnosed annually worldwide and represents the most common head and neck malignancy in the United States, as recently reported by the National Cancer Data Base [1]. Survival in patients with laryngeal cancer is dependent on the stage and site of tumour and its phenotype. It is obviously difficult, or even impossible, to control faradvanced laryngeal cancer, and it is therefore essential to concentrate on the initial steps in tumour development in order to facilitate early detection and timely implementation of suitable therapy [2]. Neoplastic development in laryngeal epithelium, as with many other epithelial cancers, is a multistep process driven by accumulating multiple and specific genetic alterations, involving oncogenes and tumour suppressor genes [3, 4]. The first morphologically unequivocal recognizable step is represented by intraepithelial abnormalities, such as dysplasia and carcinoma in situ. However, adjacent apparently normal squamous epithelium may already harbour the initial genetic abnormalities leading to malignant transformation. Early detection appears to be the best and only chance to improve the therapeutic results of laryngeal cancer. Therefore, it is necessary to recognize the initial intraepithelial neoplastic lesions. What is the earliest non-invasive malignant lesion of the larynx? To answer this question, it may be best to begin by explaining what early cancer is. In our practice, we use the term ‘early cancer’ to mean a very precisely defined entity, namely, a minimally invasive pathologic and biologic entity which does not invade muscular or cartilaginous structures, but which nevertheless possesses a (small but real) potential for metastasizing. Of necessity, then, such an ‘early’ cancer is confined to the lamina propria and, as noted above, can be no more than a minimally invasive lesion [5]. In terms of the surface area of mucosa it may involve in a given patient, however, early cancer of the larynx may be a surprisingly extensive lesion, giving rise on occasion to a so-called ‘carpet’ or ‘superficial extending’carcinoma. The critical distinction which we would advocate, however, calls for restriction of the use of the diagnostic term ‘early cancer’ to lesions in this ‘middle ground’: lesions which extend further than a purely intraepithelial proliferation (which, by definition, would be delimited by a basement membrane), yet less extensive than those proliferations which reach into adjacent skeletal muscle or cartilage. As such, we do not believe that early cancers are either in situ or T2/T3 lesions [5].