Analisys of predictors of chemoradiation (CRT) therapy efficacy on the treatment of locally advanced oropharyngeal carcinoma (LASSCO)
Alcohol consumption and tobacco are widely recognized as risk factors for squamous-cell carcinoma of oropharynx (SCCO). Recently the human papillomavirus (HPV) infection has been recognized as an important cause of SCCO. Staging tumor with TNM/AJCC system is currently the most important tool to access prognosis and guide treatment. Combination of chemotherapy and radiotherapy (CRT) is widely accepted as a treatment option for LASSCO. There is a growing interest in studying the role of HPV infection as a prognostic factor in these tumors.
We aimed to evaluate molecular tumor HPV-related markers p16 and p53 as prognostic factors for patients treated with CRT for stage III/IVa/b LASSCO and its correlation with clinical-pathological factors at diagnosis.
Patients harboring LASSCO treated with CRT at Hospital A.C. Camargo from 1995 to 2010 were retrospectively evaluated. Sociodemographic and clinical information and p16 and p53 immunochemistry were studied as potential prognostic markers.
A total of 75 patients were evaluated. The main sociodemographic characteristics are shown in Table 1.
Forty five percent of patients harboured tumors arising from tongue base, followed by palatin tonsil (40,0%) and soft palate or posterior pharyngeal wall (14,6%). Regional limph node involvement was reported in 61 (81,3%) patients at diagnosis. Most patients (66,7%) were treated with concurrent use of CRT, while 25 (33,3%) patients received induction chemotherapy followed by radiotherapy alone or associated with citotoxic drugs. With a median follow-up of 22,1 months, complete response (CR) was reported in 60 individuals (86,6%). Tumoral recurrency was observed in 18,7% of our patients, often as local or regional disease.
Among patients with stage IV and III SCCO, 83,3% and 100% achieved CR, respectively. No differences in response rate (RR) were reported regarding therapeutic modality. Approximately 70% of the patients were alive after 5 years (Figure 1). We found that primary tumor extension, achievement of CR after CRT, and alcohol and tobacco exposure were predictors of overall survival (OS), as shown in Figures 2-5. No significant differences in OS regarding age range (≤55 or >55y), limph node involvement (presence or absence) or clinical staging (III ou IV) were demonstrated.
Thirty patients had their tumor samples analysed for p53 and p16 HPV related-markers, which were found in 73% and 26% of the samples respectively. However, their presence did not show any statistical relevance regarding RR or OS.
High response rate and five-year overall survival were recorded. Primary tumor extension T4, tobacco and/or alcohol consumption, and failure to achieve complete response after CRT were significantly associated with worse prognosis.