The purpose of this study is to test the hypothesis that plasma, peripheral blood mononuclear cell and urine levels of Gemcitabine and its metabolites, 30 mins or 2 hours post infusion, predict response to GemX chemoradiation at first check cystoscopy, 3 months from the end of radiotherapy.

Inclusion Criteria:

• histologically confirmed diagnosis of muscle-invasive transitional cell carcinoma.
• suitable for treatment with radical concurrent chemoradiotherapy with GemX.
• Standard radiological assessments with CT or MR for staging.
• ECOG performance status 0-2
• Adequate pre-treatment haematological and biochemical parameters
• Age greater than or equal to 18 years
• No significant co-morbidity thereby excluding patient from having radical treatment.
• No previous treatment for diagnosis of muscle-invasive bladder cancer or other pelvic radiotherapy.
• Women of child bearing age MUST have a negative pregnancy test prior to study entry and be using an adequate contraception method, which must be continued for 3 months after the study, unless child bearing potential has been terminated by surgery/radical radiotherapy
• Patients must have given written informed consent

Exclusion Criteria:

• Patients with a known history of anaphylactic reaction to any other drug.
• Patients must not have a history of other malignant diseases other than adequately treated non-melanotic skin cancer or in-situ carcinoma of the uterine cervix
• Any evidence of severe or uncontrolled systemic diseases which, in the view of the investigator, makes it undesirable for the patient to participate in the trial.
• Evidence of significant clinical disorder or laboratory finding which, in the opinion of the investigator makes it undesirable for the patient to participate in the trial Any other serious uncontrolled medical conditions
• Clinical evidence of metastatic disease to brain
• Any pregnant or lactating woman
• Any patient with a medical or psychiatric condition that impairs their ability to give informed consent