A clinical trial of 24 people with recurrent superficial bladder cancer has shown that a combination therapy using sequential
mitomycin C and 5-aminolaevulinic acid (ALA) is safe, well tolerated and effective. Further follow up and study is needed to investigate if the low
recurrence rates are sustained but this combined therapy should be valuable for superficial bladder cancer, particularly carcinoma in situ. Previous PDT studies in the bladder used porphyrin mixtures, which tended to cause prolonged skin hypersensitivity and detrusor damage. ALA, a precursor of the photosensitizer protoporphyrin IX offers a potentially less toxic option.
In this trial, mitomycin C instillation for one hour was followed by ALA at concentrations of 6%, 8% or 10%; the light dose, at a wavelength of 635nm was increased from zero to 25 J/cm2. No significant side effects were noted. Some minor problems, such as urgency, frequency and suprapubic discomfort after urination were experienced but the analgesic requirements after therapy were minimal. All patients were tumour free for 4 months after treatment. Cumulative tumour
recurrences occurred; 2 at 8 months, 6 at 9 months, 9 at 18 months and 11 at 24 months.
The recurrence rates were low; 11 recurrences in the 2 year period following therapy compared to 29 in this group in the 18 months before enrolment. It was also encouraging that in two patients with CIS, there was only one recurrence in the two years of follow up. In both cases the disease was difficult to control before PDT with many recurrences despite active therapy with BCG immunotherapy. Future studies will focus on 40 mg mitomycin C givenfor one hour, direct bladder infusion of 6% ALA for 4 hours, following by light at 25 J/cm2 to the urothelium.