Role of computed tomography imaging in predicting response of nasopharyngeal carcinoma to definitive radiation therapy.

PURPOSE: The purpose of this study was to investigate the role of posttreatment computed tomography (CT) scans in assessing response of nasopharyngeal carcinoma (NPC) to definitive radiotherapy. MATERIAL AND METHODS: Between March 1999 and October 2003, a total of 132 consecutive patients with newly diagnosed NPC were studied. Sixty-one patients with AJCC stage I or II NPC were treated with radiation only; 71 patients with stage III or IV disease but no evidence of distant metastasis were treated with concurrent chemoradiotherapy. All patients received CT scans of the head and neck, nasopharyngoscopy, and biopsies of primary sites at 4 to 6 months after completion of radiotherapy. Clinical response of the primary tumor as determined by comparison of pre- and posttreatment CT scans was correlated to pathology results. RESULTS: The median follow-up time for all patients was 25 months (range, 9-40 months). Radiologic progression was seen in five patients, stable disease in 18 patients, and radiographic partial (rPR) and complete responses (rCR) were seen in 67 and 42 patients, respectively, at 4 to 6 months of follow up. Biopsies of the nasopharynx were positive in six patients. For patients with rCR, two patients (4.8%) had positive biopsies. Four patients with residual disease (rPR, stable, or progressive disease) after treatment had positive biopsies. The positive and negative predictive values, sensitivity, and specificity of CT scans in evaluating the NPC response to radiotherapy were 0.04, 0.95, 0.67, and 0.32, respectively. CONCLUSIONS: Pathologic CR for nasopharyngeal carcinoma is usually evident at 4 to 6 months after definitive radiotherapy; however, there is no correlation between pathologic and radiographic response. Although longer follow up is required to define the relationship between radiographic and pathologic responses with respect to disease control, we find CT scan at 4 to 6 months after radiotherapy to be neither sensitive nor specific in predicting the response of primary NPC to radiotherapy.

Prospective phase II trial of concomitant boost radiotherapy for stage II nasopharyngeal carcinoma: an evaluation of response and toxicity.

INTRODUCTION: Stage II nasopharyngeal carcinoma (NPC) treated with conventionally fractionated radiotherapy results in loco-regional control of around 80%. This report aims to document the outcome of Stage II NPC patients treated with external beam radiotherapy delivered using an accelerated concomitant boost (C-Boost) schedule. METHODS AND MATERIALS: Twenty-five 1997 AJCC Stage II NPC patients were enrolled and analyzed in this preliminary report. The primary tumor and clinically involved nodes received a total dose of 72 Gy in 42 fractions. C-Boost for gross disease consisted of 18 Gy in 12 fractions commencing on day 19 and was delivered at least 6 hours after the first dose. Patients were assessed for response, survival, and toxicity. RESULTS: With a median follow-up of 24 months, only one patient had pathologically confirmed local recurrence, necessitating IMRT. Two developed distant metastases for which they received chemotherapy. One died from systemic disease after refusing treatment for persistent neck lymphadenopathy. Two-year loco-regional control rates, overall survival and disease-free survival rates were 96%, 96%, and 88%, respectively. All patients experienced some degree of acute and/or late toxicity. However, the toxicity profile was comparable to that seen following standard fractionation. Acute or late toxicities directly attributable to C-Boost were not observed. CONCLUSION: This C-Boost radiotherapy regimen administers a substantially higher biologically effective dose compared with conventional radiation schedules. Preliminary locoregional control and survival rates are promising with no significant acute and/or late toxicities.