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Role of Computed Tomography Imaging in Predicting Response of Nasopharyngeal Carcinoma to Definitive Radiation Therapy
Author(s) -
Ma Xuejun,
Lu Jiade Jay,
Loh Kwok Seng,
Shakespeare Thomas P.,
Thiagarajan Anu,
Goh Boon Cher,
Tan Kim Siang Luke
Publication year - 2006
Publication title -
the laryngoscope
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.181
H-Index - 148
eISSN - 1531-4995
pISSN - 0023-852X
DOI - 10.1097/01.mlg.0000242046.22134.51
Subject(s) - medicine , nasopharyngeal carcinoma , radiation therapy , stage (stratigraphy) , radiology , chemoradiotherapy , biopsy , carcinoma , radiography , nuclear medicine , paleontology , biology
Abstract 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.