PET Image-Guided Radiotherapy Evaluated for Positive Paraaortic Lymph Nodes in Cervical Cancer

The purpose of a new study was to evaluate the feasibility and toxicity of positron emission tomography (PET) image-guided radiation therapy (IMRT) of 18F-fluorodeoxyglucose (FDG) PET-positive pelvic and paraaortic lymph nodes to 60 Gy in patients with carcinoma of the cervix.

Patients with cervical cancer may have paraaortic node metastasis, which occurs in 5-30% of patients depending on the clinical stage of their disease. Survival in patients with paraaortic lymph node metastases is poor regardless of presenting clinical stage of their disease, with an overall two-year survival of approximately 25%.

PET imaging with FDG has been found to have high sensitivity and specificity in the detection of pelvic and paraaortic lymph node metastases and has been shown to significantly impact prognosis. Typical radiation doses to the paraaortic lymph nodes are about 45-50 Gy. Dose escalation beyond 45 Gy has been limited because of increased toxicity with increased dose and increased volume of irradiated small bowel. The researchers theorized that dose escalation to the paraaortic lymph nodes could be performed with acceptable toxicity and that it might improve survival.

In this prospective phase II study, 24 patients received PET-guided IMRT to deliver 60 Gy to the PET positive pelvic and paraaortic lymph nodes. Patients received external irradiation to the pelvis and paraaortic region, intracavitary brachytherapy, and concurrent chemotherapy with weekly cisplatin.

The results of this study suggest that PET image-guided IMRT to 60 Gy to pelvic and paraaortic lymph nodes with concurrent chemotherapy resulted in the elimination of nodal disease in most patients (89%), but survival is poor (23% at three years) due to the development of distant metastatic disease. The acute grades III and IV toxicities were 58% and 33%, respectively. One patient died from complications of therapy.

Dr. Grigsby Perry and colleagues from the Mallinckrodt Institute of Radiology (St. Louis, MO, USA) presented their study's findings at ESTRO (European Society for Therapeutic Radiology and Oncology) 27, September 2008, held in Gothenburg [Göteborg], Sweden.

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Mallinckrodt Institute of Radiology