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


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.
Ma
Xuejun
X
Department of Radiation Oncology, Cancer Hospital of Fudan University, Shanghai, China.
Lu
Jiade Jay
JJ
Loh
Kwok Seng
KS
Shakespeare
Thomas P
TP
Thiagarajan
Anu
A
Goh
Boon Cher
BC
Tan
Kim Siang Luke
KS
D000328:Adult; D001706:Biopsy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000532:radiotherapy*; D011379:Prognosis; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome