International Journal of Radiation Oncology*Biology*Physics
Clinical investigation: cervixMeasurement of tumor volume by PET to evaluate prognosis in patients with advanced cervical cancer treated by radiation therapy☆
Introduction
Positron emission tomography (PET) employing the radiopharmaceutical 18F fluorodeoxyglucose (FDG) is used in staging and follow-up of a wide variety of cancers, including lymphoma, malignant melanoma, and carcinomas of the esophagus, breast, lung, and colon (e.g., Refs. 1, 2, 3). Work from our institution 4, 5 and elsewhere 6, 7, 8 has shown that PET is also valuable in staging patients with cervical carcinoma. FDG-PET readily identifies the primary tumor and accurately assesses spread to lymph nodes and distant metastases.
It is well established that tumor size is an important prognostic factor in patients with cervical carcinoma 9, 10. Although clinical stage also is an important factor, stage does not necessarily correlate with tumor size. The limited reliability of physical examination for estimation of size has led to interest in tumor measurement based on three-dimensional imaging techniques 11, 12, 13, 14, 15. The work presented here is an attempt to increase the already substantial value of PET in patients with advanced cervical cancer by addition of information about the size of the primary tumor. A quantitative technique is described that accurately measures the tumor volume, with the results showing a strong correlation with treatment outcome, especially when combined with detection of lymph node disease.
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Patients and treatment
Fifty-one consecutive patients with newly diagnosed advanced cervical carcinoma whose digital data were available were included in this retrospective study. All patients were to be treated by radiation therapy. The patients underwent PET imaging for clinical indications before treatment between January 1998 and September 1999. They were treated exclusively with irradiation and, in 29 patients, concurrent cisplatin-based chemotherapy (16). The radiation therapy consisted of 6 weeks of external
Results
A typical example of the PET/CT correlation used to validate the PET edge detector is presented in Fig. 1. The slice best demonstrating the maximum dimensions of the primary tumor is shown, along with marks indicating the boundaries of the tumor. To retain maximum spatial resolution, the CT dimensions were measured directly from film and not from the interpolated, digitized images shown in the figure.
The results for a threshold value of 40% are shown in Fig. 2, along with the correlation
Discussion
Failure of initial treatment with radiation therapy is associated with a poor salvage rate and reduced long-term survival in patients with advanced cervical carcinoma. It is critically important that the initial course of therapy be effective, because many studies show that the primary cause of poor long-term survival after definitive radiotherapy is failure to achieve local control (e.g., Refs. 23, 24, 25). Thus, ways are needed to identify patients at high risk who may be candidates for more
Acknowledgements
We are grateful to Katherine Trinkaus, Ph.D., for help with the statistical analysis and to Patsa Hungspreugs and Jason Jacob for their work with data analysis.
References (28)
- et al.
PET and 18F-FDG in oncologyA clinical update
Nucl Med Biol
(1996) - et al.
FDG-PET evaluation of carcinoma of the cervix
Clin Positron Imag
(1999) - et al.
Tumor size, irradiation dose, and long-term outcome of carcinoma of uterine cervix
Int J Radiat Oncol Biol Phys
(1998) - et al.
Usefulness of tumor volumetry by magnetic resonance imaging in assessing response to radiation therapy in carcinoma of the uterine cervix
Int J Radiat Oncol Biol Phys
(1996) - et al.
Tumor size evaluated by pelvic examination compared with 3-D MR quantitative analysis in the prediction of outcome for cervical cancer
Int J Radiat Oncol Biol Phys
(1997) - et al.
Tumor diameter/volume and pelvic node status assessed by magnetic resonance imaging (MRI) for uterine cervical cancer treated with irradiation
Int J Radiat Oncol Biol Phys
(1999) - et al.
Staging, volume estimation, and assessment of nodal status in carcinoma of the cervixComparison of magnetic resonance imaging with surgical findings
Clin Radiol
(1994) - et al.
Tumour oxygenation levels correlate with dynamic contrast-enhanced magnetic resonance imaging parameters in carcinoma of the cervix
Radiother Oncol
(2000) - et al.
Oncological applications of positron emission tomography with fluorine-18 fluorodeoxyglucose
Eur J Nucl Med
(1996) - et al.
A tabulated summary of the FDG PET literature
J Nucl Med
(2001)
Lymph node staging by positron emission tomography in patients with carcinoma of the cervix
J Clin Oncol
Positron emission tomography for evaluating para-aortic nodal metastasis in locally advanced cervical cancer before surgical stagingA surgicopathologic study
J Clin Oncol
Evaluation of FDG-PET in patients with cervical cancer
J Nucl Med
Metastatic lymph nodes in patients with cervical cancerDetection with MR imaging and FDG PET
Radiology
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This project was supported in part by Grant No. R01 CA85797 from the National Institutes of Health. This work is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.