PET Scans For Decision-Making In Metastatic Renal Cell Carcinoma: A Single-Institution Evaluation

UroToday.com- While PET scans with flourodeoxyglucose have been embraced as a staging tool in a wide variety of oncologic subspecialties, the role of PET scanning in directing the therapy of patients with metastatic renal cell carcinoma (mRCC) remains unclear. Here, Dilhuydy and colleagues examine their limited experience with this imaging modality in directing therapy for patients with mRCC.

The authors examined the results of 26 PET scans in 24 patients that were treated with systemic therapy (immunotherapy or medroxyprogesterone acetate) for mRCC. The median interval from end of systemic therapy to PET scanning was 4.8 months. Of these 24 patients, 18 had measurable disease on conventional (computed tomography) imaging, 5 had a complete response to therapy, and 1 had a complete response and was awaiting a heart/lung transplant.

The authors asked whether or not PET scanning might provide additional information regarding the status of disease that might somehow alter the direction of therapy. Median follow-up on all patients was 24 months (range 6-34 months). In three patients with what was thought to be limited metastatic disease, where surgical extirpation was planned, PET scanning demonstrated more widespread disease, and patients were referred for additional systemic therapy rather than surgery.

In two patients thought to have a complete response based on conventional imaging (and therefore were to be surveilled for evidence of recurrence), PET scanning demonstrated persistent disease in the thorax and mediastinum, and the therapeutic plan in each patient was changed to surgical extirpation, where the presence of persistent disease was confirmed on pathologic examination of the resected specimens.

Therefore, the therapeutic plan was changed in 5 (20.8%) of patients based on the results of the PET scan. The authors noted that the sensitivity of PET scanning (relative to conventional imaging) was 75% and the positive predictive value was 92.3% in their study.

PET scanning may have a limited role in the evaluation and management of patients with mRCC. The authors advocate the use of this imaging modality in patients with limited metastatic burden being considered for surgical intervention, to rule out the presence of more widespread metastases, as well as in the clinical scenario of a complete response to systemic therapy, to rule out the presence of residual viable disease that might warrant additional therapy.

Dilhuydy MS, Durieux A, Pariente A, de Clermont H, Pasticier G, Monteil J, Ravaud A.
Oncology 70(5): 339-344, 2006.

Reviewed by UroToday.com Medical Editor Christopher G. Wood, MD, FACS

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