Positron emission tomography with L-methyl-11C-methionine in the monitoring of therapy response in muscle-invasive transitional cell carcinoma of the urinary bladder

• OBJECTIVE: To investigate whether positron emission tomography (PET) with L-methyl-11C-methionine as a tracer could be used for diagnostic purposes and for evaluation of therapy in patients with varying stages of urinary bladder cancer treated with chemotherapy. PATIENTS AND METHODS: PET was employed in 44 separate examinations involving 29 patients (24 men and five women with a median age of 68 years [mean 66, range 47-78]) with localized or metastatic transitional cell carcinoma of the urinary bladder. In four patients PET examinations were performed prior to the commencement of chemotherapy, and after one course and after three courses. RESULTS: The diagnostic accuracy of PET was poor. The technique did not monitor the therapeutic effect of neoadjuvant chemotherapy, producing results that correlated with therapy outcome. PET identified those patients who responded less successfully to therapy. CONCLUSION: PET with L-methyl-11C-methionine demonstrates alterations in tumour metabolism long before visible changes appear on computed tomography or magnetic resonance imaging. Further work is required to develop more specific tracers.

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