Predictive value of the flow cytometric PCNA assay (proliferating cell nuclear antigen) in head and neck tumors after accelerated-hyperfractionated radiochemotherapy

Purpose: Proliferation of tumor cells during radiotherapy may limit tumor control, especially in rapidly proliferating tumors such as head and neck carcinomas. We present a flow cytometric method for detection of PCNA in solid head and neck tumors and how these data correlate with outcome. Methods and Materials: Pretherapeutic biopsies of 20 inoperable patients with Stage IV squamous cell carcinoma were examined. Biparametric flow cytometry was done after anti-PCNA (PC10) and propidium iodine staining were performed. PCNA index (percentage PCNA positive cells), DNA index, and S phase fraction (SPF, euploid tumors only) were determined. The therapy consisted of an accelerated-hyperfractionated radiochemotherapy (66 Gy/5 weeks, concomitant boost of 1.6Gy/day in weeks 4 + 5, Carboplatin 5 x 70 mg/m(2) in weeks 1;5). The median follow-up time was 30 months. Results: Fourteen patients suffered from disease progession and 12 died. Median actuarial, cause-specific survival, and disease-free survival (DFS) times were 17 and 9 months, respectively. PCNA indices ranged from 4 to 70% (median 9%); there were 7 aneuploid and 13 euploid tumors. SPF ranged from 4 to 14.5% (median 10.5%). Neither SPF nor ploidy had a significant influence on outcome. Patients were divided according to PCNA index in higher (n = 10) and lower (it = 10) than the median. Survival and DFS were 13 and 6 months for the group >9% and 20 and 15 months for the group