Computed tomography in the management of nasopharyngeal carcinoma

Locally advanced nasopharyngeal carcinoma: computed tomography findings, clinical evaluation, and treatment outcome

PURPOSE

We present our experience with computed tomography (CT) for delineating the extent of bone erosion in nasopharyngeal carcinoma (NPC) and propose that a new subdivision of Stage T4 disease be added to the staging criteria for cases of minimal bone disease, defined as erosion of the base of the sphenoid or the pterygoid without cranial nerve (CN) involvement.

METHODS AND MATERIALS

We retrospectively reviewed the clinical findings, radiological findings, and treatment outcome in 64 patients with Stage T4 NPC, diagnosed according to the American Joint Committee on Cancer 4th edition criteria. The median follow-up was 34 months (range, 3-118 months). Statistical analyses were performed using the chi-square test, the Kaplan-Meier method, and the log-rank test.

RESULTS

Local control was achieved in 19 (46%) of 41 patients with CN deficits and 18 (78%) of 23 patients without CN deficits (p = 0.01). Overall 5-year survival with and without CN deficits was 25% and 58%, respectively (p = 0.01). When the 16 patients with minimal bone disease were compared to the remaining 48 patients, there were significant differences in local control rates (87% vs. 48%, p = 0. 006) and 5-year survival rates (68% vs. 28%, p = 0.008).

CONCLUSION

Among patients with Stage T4 NPC, a subgroup of patients with only minimal bone disease may have a more favorable prognosis, which may have a considerable bearing on our approach to this patient group.

MRI of nasopharyngeal carcinoma with emphasis on relationship to radiotherapy

MRI has been used increasingly in the evaluation of nasopharyngeal carcinoma (NPC) because of its good tissue contrast and multiplanar capacity. Although there are some controversies in assessing skull base invasion and cervical metastatic adenopathy, recent reports demonstrate that MRI is currently better than or as good as CT in defining the extent of NPC. During follow-up of patients with NPC after radiotherapy, MRI is also more effective than CT in demonstrating tumor recurrence and in detecting postradiation complications. However, the difficulty of using MRI to detect early mucosal recurrence and to differentiate postradiation tissue changes from local tumor recurrence should be recognized. This paper reviews the literature regarding MRI of NPC related to radiotherapy, with special emphasis on treatment planning, recurrence assessment, and complication detection.

Magnetic resonance imaging and computed tomography features of nasopharyngeal carcinoma with maxillary sinus involvement

Anterior spread of nasopharyngeal carcinoma (NPC) may infiltrate the maxillary sinus. In a prospective study of 114 patients comparing magnetic resonance imaging (MRI) and computed tomography (CT) in the staging of NPC, 10 (9%) patients were noted to have tumour infiltration of the maxillary sinuses. All of the patients except one had associated infiltration of the sphenoidal sinuses indicating advanced local spread. Computed tomography was excellent in outlining the extent of bony erosion and associated soft tissue mass within the antra. T1-weighted images could not demonstrate bony erosions directly although soft tissue extension into the sinuses could be clearly visualized. Both CT and MRI showed good demarcation between tumour and mucosal thickening within the maxillary sinus. Although MRI demonstrated soft tissue involvement more elegantly than CT, it did not appear to offer significantly more information that may affect clinical management.

CT-based radiotherapy treatment planning for cancer of the nasopharynx

We analysed 32 cases of nasopharyngeal carcinoma (NPC) treated with radiotherapy trying to define the role of CT scan during radiotherapy planning, as well as radiation treatment and the follow-up of the patients. CT scan was found to help 15 cases with low-parapharyngeal involvement and/or bone erosion. Persistent abnormal CT findings at 2 mo after the end of radiation treatment were related to a 30% local recurrence rate. This rate went up to 100% in case of skull-base destruction.

Comparison of plain radiographs and computed tomographic scanning in nasopharyngeal carcinoma

Plain radiographs, computed tomographic (CT) scans and clinical records of 100 patients with nasopharyngeal carcinoma were studied. CT scans and plain radiographs provided similar information in 46 patients. There were 54 cases in which the two techniques disagreed. In 45 cases CT demonstrated abnormalities not seen in plain radiographs and in nine cases plain radiographs demonstrated abnormalities not seen with CT scanning. Based on the total information gained from clinical examination, the imaging investigations, biopsies, and subsequent clinical course and investigations it appeared that none of the abnormalities predicted by plain radiographs alone could be substantiated. Conversely the CT abnormalities could be supported as being correct. We conclude that CT alone is the undoubted investigation of choice where this is available. Plain films provide less information, are unreliable and, where CT is available, superfluous.

MRI differentiation of recurrent nasopharyngeal carcinoma from postradiation fibrosis

A prospective study was performed to determine the usefulness of magnetic imaging (MRI) in differentiating local recurrence versus post-irradiation fibrosis in 72 patients after radiotherapy of nasopharyngeal carcinoma (NPC). All patients had a soft-tissue mass in the nasopharynx demonstrated by computed tomography. A total of 29 patients had tumor recurrence; 40 patients had only radiation fibrosis; 1 patient had postradiation edema and 2 patients had inflammatory changes. Based on the differences in signal intensity on T2-weighted images, MRI may be promising as a noninvasive method for differentiating radiation fibrosis from local recurrent NPC. However, the signal intensity pattern of the tumor is not specific and may be seen in radiation edema and infection.

Computed tomography in nasopharyngeal carcinoma: Part II: Impact on survival

Two hundred and seventeen consecutive patients affected by nasopharyngeal carcinoma (NPC) were treated with radiotherapy alone, with curative intent, from 1970 to 1985 at the Radiotherapy Unit of the University and Hospital of Florence. A group (A) of 111 patients staged with conventional clinical and radiological method was compared to a second group (B) of 106 patients who underwent CT staging before treatment. Group B showed better 5-year NED survival and local control; only the differences in local control were significant (p less than 0.01). As to primary control statistically significant differences were observed in T2 and T4 cases. We feel that CT could have contributed to the improvement, probably through a more reliable display of the primary extent and a more adequately planned radiotherapeutic treatment. With CT staging we could not increase our skills in prognostically separating stages according to UICC criteria (1978); in Group B only T2 patients presented significant differences in primary control when compared to T3 and T4 patients. However, a multivariate analysis of prognostic factors showed that nodal involvement, primarily, and histology, secondarily, were the most important factors; T stage showed a minor influence on prognosis.

Bone scintigraphy in nasopharyngeal carcinoma

One hundred and forty-three patients (Group 1) with histologically proven nasopharyngeal-carcinoma (NPC) had bone scintigraphy with 99Tcm methylenediphosphonate (MDP) or dihydroxypropanediphosphonate (DPD) within 2 months of the initial diagnosis. A further 162 patients (Group 2) had bone scans during the course of follow-up if there were symptoms of bone pain or evidence of metastases at other sites. Twenty-three per cent (33/143) of the newly diagnosed NPC patients (Group 1) had evidence of bone metastases. Of these 143 patients, 101 were T0-T2, 16 were T3 and 25 were T4. Thirty-six patients had no neck nodes (NO), 44 were N1, 25 N2 and 38 N3. Of the 162 patients in Group 2, 96 (59%) had a positive bone scan. The commonest sites for bony metastases from NPC were the spine, ribs, pelvis and lower limbs in order of frequency. There is a highly significant association with the nodal stage but no association with the UICC T staging which is not adequate in nasopharyngeal carcinoma. In our part of the world, bone metastases from NPC are a common cause of an abnormal bone scan.