MIB-1 and involucrin expression in laryngeal squamous carcinoma: the relationship to host and tumour factors and survival.

MIB-1 is an antibody which attaches to the Ki67 antigen expressed by proliferating cells. MIB-1 immunoreactivity may be used to quantify the proliferative component of a tumour. Involucrin is a protein expressed by mature keratinocytes and may be used as a marker of differentiation. 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 the larynx using antibodies to "Ki67' and involucrin. The median potential 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 was 56%. Fifteen patients had no or only slight involucrin staining whereas 34 stained intensely for this protein. Involucrin expression was found to be associated with histological grade with those patients expressing involucrin tending to have well differentiated tumours and those not expressing this parameter tending to have poorly differentiated tumours (P = 0.045). There were no other associations between host and tumour factors and the various biological parameters. Survival analysis demonstrated that patients with an involucrin count above the median 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 poor) involucrin expression had an increased risk of developing a recurrence at the primary site (P < 0.05). Involucrin appears to be a promising marker of tumour differentiation and survival in squamous carcinoma of the larynx.