1031 The role of 18-fluorodeoxyglucose positron emission tomography (PET SCAN) in postradiotherapy nasopharyngeal cancer

212

1. J. Radiation

Oncology

l Biology

l Physics

Volume

45, Number

3 Supplement

1999

Conclusion: Day-of-treatment pattern of contrast enhancement is confirmed in a large series to be a significant prognostic factor for FFP of brain metastases treated with RS. Multivariate analysis verifies that the finding is not just a factor of tumor volume or RS dose. One explanation may be the relative radioresistance of hypoxic cells associated with necrotic regions within heterogeneously or ring enhancing lesions. This finding has implications for the selection of patients for RS and for RS dose prescription, Future investigations may identify ways to improve the response of necrotic lesions, possibly through the use of radiosensitizers, hypoxic cell sensitizers, or strategies to improve tumor oxygenation with or without inhaled carbogen.

1029

A PHASE II TRIAL RADIOSURGERY PRIMARY BRAIN

Wasserman

TH’;

Scott

OF THE FOR THE TUMORS

RADIOSENSITIZER: ETANIDAZOLE (SR-2508) TREATMENT OF RECURRENT PREVIOUSLY OR BRAIN METASTASES (RTOG PROTOCOL

C’, Shaw E3, Drzymala

R’, Cmelak

AJ4; Coleman

N5, Souhami

WITH IRRADIATED #95-02)

L6

Washington University Medical Center, St. Louis, MO, USA’; Radiation Therapy USA”; Wake Forest University, Winston-Salem, NC, lJSA3; Vanderbilt University, Radiotherapy, Boston, MA, USA’; McGill University, Montreal, PQ. Canada6

Oncology Nashville,

Purpose/Objective: radiosurgery (SRS)

with high dose single fraction tumors or brain metastases.

To evaluate the role of hypoxic cell sensitizer (etanidazole) in patients with recurrent previously-irradiated primary brain

Group, Philadelphia, PA, TN, lJSA4; Joint Center for stereotactic

Materials and Methods: The RTOG opened the study in October 1995 and accrued 51 patients in two years. The patient population was recurrent or persistent primary brain tumors or brain metastases, who had received previous external radiation (RT). The study was compared retrospectively to RTOG study #90-95, which was a phase I study of stereotactic radiosurgery alone (SRS) in the same population of patients. The study used a single dose of SR-2508 at 12 gm/m’ which represents a high therapeutic single dose taken from previous experience with intraoperative radiation. The SRS dose varied with the maximum tumor diameter (520 mm, 24 Gy; 21-30 mm, 18 Gy; 31-40 mm, 15 Gy). The SRS doses were prescribed to the tumor margin, as defined by contrast enhancement, at the 50-908 isodose line. A total of 46 patients were evaluable (16 in the 24 Gy group; 18 in the 18 Gy group; and 12 in the 15 Gy group). Results: The study was closed prematurely due to the lack of drug availability. The median survival time for all patients was 11.5 months which compares to 9 months for RTOG protocol #90-05. There are only slight differences in survival time based on the size of the lesion and the SRS dose. Patients with a recurrent primary tumor had a longer median survival time compared to patients with metastases. Forty percent of patients failed within the treated volume equivalent to study #90-05. Conclusion: There appears to be no difference in the failure pattern or overall risk of failure or survival between study #95-02 with etanidazole and study #90-05 without etanidazole in a retrospective comparison. Hypoxic cell sensitizers remain to be established as useful agents, in this setting.

1030

FRACTIONATED

Lederman

GS, Lowry

Staten Island

STEREOTACTIC

J, Wertheim

Universily

Hospital,

RADIOSURGERY

(FSR)

M, Silverman

P, Lombardi

S; Fine M, Raden Staten island,

FOR

ACOUSTIC

NEUROMA

E, Qian G, Pannullo

S, Arbit

(AN) E

NY, USA

Purpose: FSR offers the advantage of divided dose treatment with the precision of stereotactic radiosurgery Gill-Thomas-Cosman relocatable head frame. FSR should result in superior outcome because of radiobiologic surrounding structures while maintaining efficacy of treatment.

for AN using the repair of normal

Materials and Methods: Described are 68 patients (pts) aged 21-88 years (mean 58) with 68 AN ranging in volume from 0.1-32.0 cc (mean 5.0). 47 AN had maximum diameters (3 ems (range 0.2-2.8, mean 1.5) and 22 measured 3 ems or greater (range 3.0-5.0, mean 3.5). 2000 Centigray (cGy) divided in 4 or 5 fractions was delivered utilizing stereotactic radiosurgery technique. Tumors larger than 3 cm have 5 fraction FSR. Results: Clinical follow-up was 14-64 mos (median 32.2). AN (3 ems had clinical follow up of 14-64 mos (median 18 AN (38%%) decreasing in size, 29 (62%) showing cessation of growth. Of 46 with pure tone audiometry, 6 (13%) 34 (74Y0) remained stable and 6 (13%) worsened. One elderly pt with uncontrolled hypertension had transient facial which resolved. Of 58 pts. 38 (66%) had improved balance and 19 (32%) stable. Clinical follow-up for 22 AN 3 ems was 15-62 mos (median 31.4). 59% decreased in size. The remainder showed cessation of growth. Of 11 pts with audiometry 2 (18%) improved, 8 (73%) were stable and 1 (9%) worsened. Of 17 symptomatic pts, 13 (76%) had balance and 3 (18%) were stable and 1 (6%) worsened. No pt had surgery for treatment failure. Conclusion: vast majority treatment.

103

1

32.5) with improved, weakness or greater follow-up improved

FSR is an effective treatment for pts with AN either less than or greater than 3cms in maximum diameter. of pts after FSR maintain hearing, avoid facial or trigeminal neuropathy and remain in remission years

THE ROLE OF 1%FLUORODEOXYGLUCOSE INPOSTRADIOTHERAPYNASOPHARYNGEALCANCER

Al-Amro AS, Saleem King Faisal Specialist

M, Bakheet SM. Al-Rajhi NM, Hospital and Research Center,

Purpose: Postradiotherapy disease may be translated

POSITRON Larsson Riyadh,

EMISSION

TOMOGRAPHY

(PET

The after

SCAN)

S. Powe J Saudi Arabia

nasopharyngeal fibrosis represents a diagnostic dilemma. to better cure rate if thrapy is implemented. Neither clinical

Early detection of persistent exam nor current anatomical

or recurrent studies can

Proceedings

differentiate of recurrent

between benign nasopharyngeal

post therapy cancer.

of the 41st Annual

fibrosis

or recurrence.

This

ASTRO

273

Meeting

study is testing

the value of PET scan in early detection

Materials and Methods: Forty-nine patients (32 male, and 17 female) underwent 2-18 FDG PET scans post radiotherapy treatment for nasopharyngeal cancer. Age range from 13 to 80 years of age (median 46) and their radiotherapy performed 3-217 months prior to the PET scan (median 16 months). We compared the 18.FDG PET scan with the clinical findings, CT scan, Pathological studies and other diagnostic studies. Results: All patients had the diagnosis of squamous cell carcinoma of the nasopharynx confirmed. Radical radiotherapy was given to all patients 3-217 months prior to the PET scan (median 16 months). Clinical staging using UICC system was as follows; 3 had Tl, 9 T2, 21 T3, and 13 T4, 10 NO, 8 Nl, 10 N2, 15 N3, and 1 Nx, and no staging available in 3 patients. Both clinical exam and CT head and neck showed abnormality in the nasopharynx in 34 patients. Among those, 25 patients had asymmetry in the CT scan which is difficult to ensure to be only post therapy fibrosis. Nine patients had positive PET scan in the primary site confirmed pathologically to be recurrent in 4 patients and the rest did not have biopsy due to the presence of concurrent distant disease. Only two of the 25 patients who had asymmetry in the CT scan showed positive PET scan; both patients had pathological confirmation. The 23 patients who had normal PET scan and abnormal CT scan, seven of them had biopsy and were reported to be negative. The rest were followed clinically and none progressed to have recurrent disease. Ten patients had positive nodal disease on PET scan; only only had negative biopsy. Conclusion:

Eighteen

1032

FDG PET scan is a useful

TREATMENT OF MAXILLARY AJCC STAGING SYSTEMS

Le QT’,

Fu K’, Kaplan

Stanford

University

M’,

Medical

Terris Center,

D’, Fee W’, Stanford,

tool in differentiating

SINUS

Goffinet CA,

USA’;

CARCINOMAS:

between

post radiotherapy

A COMPARISON

fibrosis

OF THE

and recurrent

1983 AND

disease.

1997

DR’ University

of California,

San Francisco,

San Francisco,

CA,

USA2

Objectives: carcinoma, tumors

To assess effectiveness of 1997 AJCC staging system in predicting survival and local control in maxillary sinus and to identify important prognostic factors for overall survival, local control, and distant metastasis for these

Methods and Materials: Niney-seven patients with maxillary sinus carcinoma were treated with radiotherapy at SUH and UCSF between 1959-1996. Fifty-eight had squamous cell carcinoma, 4 adenocarcinoma, 16 undifferentiated carcinoma, and 19 adenoid cystic carcinoma. Patients were staged clinically according to the 1983 and the 1997 AJCC staging systems. Tumor staging distribution for both staging systems is shown below. Eleven patients had nodal involvement at diagnosis. Thirty-six patients were treated with definitive radiotherapy alone, and 61 received combination of surgical and radiation treatments. The median follow-up for alive patients was 78 months. Results: The 5 and IO-year acturarial survival for all patients were 34% and 3 1% respectively. The 5-year survival estimates according to the 1983 and the 1997 T-staging system is shown below. The 1997 staging system was significantly better in predicting survival than the 1983 staging system. Important prognostic factors for survival on multivariate analysis included age (favoring younger age, p < O.OOl), 1997 T-stage (favoring T2-3, p = O.OOl), nodal involvement at diagnosis (favoring NO, p = 0.002), treatment modality of the primary site (favoring surgery and radiotherapy, p = 0.009), and gender (favoring female patients, p=O.O4). The overall radiation time was of borderline significance (favoring shorter time, p = 0.06). The actuarial 5-year local control rate was 43 percent. Local control rate by T-stage according to the 1983 and the 1997 staging systems are shown below. The 1997 staging system was superior in predicting local control between T-stages, although the difference was not statistically significant. The only important prognostic factor for local control for all patients on multivariate analysis was local therapy, favoring surgery and radiotherapy over radiotherapy alone (p < 0.001). For patients treated with surgery, pathologic margin status correlated with local control (p=O.O07) and for patients treated with radiation alone, higher tumor dose (p=O.O07) and shorter overall treatment time (p=O.O4) were associated with fewer local relapses. The 5-year estimate of freedom-from-distant metastasis was 66 percent. The 1997 T-stage, N-stage, and nodal relapse were adverse prognostic factors for distant metastasis on multivariate analysis. There were 22 complications in 16 patients, representing a 30% actuarial risk of developing late complications at 10 years. Conclusion: The 1997 AJCC staging system was superior to patient population. Combined surgical and radiation treatment than radiotherapy alone. Other important prognostic factors for overall radiation time was associated with poorer survival and treatment of these tumors in long-term survivors. Improved surrounding normal tissues.

Pts: patients;

OS:

the 1977 in predicting both survival to primary sites yielded higher survival survival were patient age, gender, and local control. Late severe toxicity was radiotherapy techniques shold lead

overall survival, LC: local control; yr: year.

and local control in this and local control rates nodal stage. Prolonoged a significant problem in to decreased injury to