18F PET

Renal cell carcinoma (RCC) is diagnosed in over 6000 patients and accounts for approximately 2% of malignant disease annually in the UK. Many patients initially present with advanced or unresectable disease and up to 30% of patients treated by nephrectomy with curative intent for localised disease will relapse. The mainstay of curative treatment for renal cell carcinoma is surgery; nephrectomy has also been shown to be of palliative benefit in metastatic disease for fit patients with a symptomatic primary lesion or who used to proceed to immunotherapy in the era before tyrosine kinase inhibitors. Surgical resection of solitary bone metastasis is an important consideration to maintain quality of life for selected patients.

The current techniques used for detecting bone metastases in advanced renal cell carcinoma have low sensitivity. A very high sensitivity is required in two groups of patients: those that are thought to have no metastases and will undergo curative resection and those that have a solitary bone metastasis that will undergo resection of both the primary and the solitary metastasis. In both these groups, knowledge of a second metastasis will alter patient management. We propose that an imaging test with a very high sensitivity for bone metastases will have a clinical role in these patients.

There is evidence from other groups of patients with skeletal metastases that Na₁₈F-PET-CT has a higher sensitivity for detecting bone metastases than _99mTc-MDP bone scintigraphy. This has not been explored in patients with renal cell carcinoma and this pilot trial will address this question. Furthermore, Na₁₈F-PETCT takes a shorter amount of time than conventional scintigraphy, provides an equivalent dose to the patient, and may help to overcome the current supply problems that are being encountered with 99mTc-based agents. Although it is more expensive than a bone scintigram, the cost could be counterbalanced by reducing unnecessary surgery although this would require a formal cost-benefit analysis.

Patients will be recruited from the renal oncology clinic as well as at Multidisciplinary Team meetings (MDTs). This is a single centre feasibility trial that will recruit 10 patients in the first instance with known or suspected metastatic renal cell carcinoma i.e. M1 disease. Patients with known bone metastases will have been detected with _99mTc-MDP bone scintigraphy or CT (which are routine investigations for patients with RCC) or another imaging investigation e.g. plain film or MRI. For the purposes of this trial, bone metastases may be suspected if there is bone pain, a bone mass or neurological symptoms felt to be due to bone metastases. All patients will be aware that they have or are suspected to have, bone metastases.

The total duration of the trial is 3 years. This includes a 2 year recruitment period and a 1 year follow-up period. Subjects will be on the trial for a maximum of 2 months; however information about their disease progression will be collected for up to 1 year after they complete the trial. The primary objective is to determine if ₁₈F-labelled sodium fluoride Na1₈FPET-CT is more sensitive at detecting bone metastases in renal cell carcinoma than conventional techniques i.e. bone scintigraphy (including SPECT of the lower abdomen/pelvis) and computed tomography (CT). Number, site, and extent of metastases will be evaluated.

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