MIB-1 AND INVOLUCRIN EXPRESSION IN LARYNGEAL SQUAMOUS CARCINOMA - THERELATIONSHIP TO HOST AND TUMOR FACTORS AND SURVIVAL

MIB-1 is an antibody which attaches to the Ki67 antigen expressed by p roliferating cells. MIB-1 immunoreactivity may be used to quantify the proliferative component of a tumour. Involucrin is a protein expresse d by mature keratinocytes and may be used as a marker of differentiati on. The present paper studies the expression of these two markers in a group of patients with squamous carcinoma of the larynx. Tumour cell kinetics were studied in 49 patients with squamous cell carcinoma of t he larynx using antibodies to 'Ki67' and involucrin. The median potent ial follow-up for the group was 8.1 years with a minimum follow-up of 5 years. The median MIB-1 index was 32%. The median involucrin index w as 56%. Fifteen patients had no or only slight involucrin staining whe reas 34 stained intensely for this protein. Involucrin expression was found to be associated with histological grade with those patients exp ressing involucrin tending to have well differentiated tumours and tho se not expressing this parameter tending to have poorly differentiated tumours (P = 0.045). There were no other associations between host an d tumour factors and the various biological parameters. Survival analy sis demonstrated that patients with an involucrin count above the medi an value had a better 5-year survival than those below the median (89% and 56% respectively) (P < 0.05). In addition, patients with no (or p oor) involucrin expression had an increased risk of developing a recur rence at the primary site (P < 0.05). Involucrin appears to be a promi sing marker of tumour differentiation and survival in squamous carcino ma of the larynx.