TUNEL - an efficient prognosis predictor of salivary malignancies

Abstract

Biological markers are necessary for predicting prognosis of salivary malignancies and better understanding the pathogenesis of salivary cancer. We analysed terminal deoxynucleotidyl transferase (TdT)-mediated biotinylated deoxyuridine-triphosphate (dUTP)-biotin nick-end labelling (TUNEL), p53 and Ki67 expression in 66 patients with malignant salivary tumours by immonohistochemistry, and correlated the data with survival, disease-free survival, tumour grade, stage, and local and distant metastasis. TUNEL efficiently predicted poor prognosis in salivary malignancies. The 5-year (5Y) survival probability dropped significantly with the level of TUNEL staining (from 83% in negatively stained tumours to 57 and 24% in TUNEL positively stained levels 1 and 2, respectively), (P=0.042). Extensive Ki67 staining (in addition to TUNEL) reduced the 5Y-survival rate even further and addition of positively stained p53 dropped the 5Y-survival rate to 0. The correlation rates between TUNEL and Ki67 was 58% (P=0.0001), and between TUNEL and p53 it was 50% (P=0.035). Concurrently, TUNEL correlated with metastasis, extracapsular spread, grade and stage. The correlation between TUNEL, p53 and Ki67 staining and survival probabilities, and the pathological grade, stage and metastasis spread of salivary malignancies makes this a highly effective tool in patient follow-up and prognosis.

Figure 1

Survival probability curves of salivary-gland tumour patients according to TUNEL immunostaining levels. Kaplan–Meier analysis (age-adjusted) showed poor survival in patients with positive TUNEL expression. Follow-up of 120 months showed 24% survival of TUNEL – level 2-positive patients compared with 66% survival of patients with no detectable TUNEL expression. (P=0.042).

Figure 2

DFS probability curves of salivary-gland tumour patients according to TUNEL expression levels. Kaplan–Meier analysis (age-adjusted) showed significantly poorer DFS in patients with positive TUNEL staining than those with negative (0) TUNEL expression. Follow-up of 120 months (10 years) showed 23% survival of level 2-positive TUNEL-staining patients, compared with 78% survival of patients with negative staining (P=0.05).

Figure 3

Immunohistochemical staining of TUNEL in patients with salivary malignant tumours. Formalin-fixed, paraffin-embedded  mm sections of salivary gland tumours were subjected to immunostaining of TUNEL. Representative photomicrographs of negative (A) acinic cell carcinoma and positive (B) mucoepidermoid TUNEL staining are presented.