Treatment of bladder carcinoma with irradiation combined with misonidazole

A feasibility study of partially accelerated radiotherapy for invasive bladder cancer

Thirty-nine patients with histologically confirmed invasive bladder carcinoma (T2-3, N0, M0) were treated with a partially accelerated radiotherapy scheme. After 40 Gy/4 weeks of conventional fractionation we have accelerated the treatment in the last week giving two daily fractions of 2 Gy each, 4-6 h apart in the bladder only. Although the follow-up of some of the patients is not very long our results indicate that this relatively short radiotherapeutic scheme is feasible, convenient and probably safe for patients living in remote areas.

A prospective randomised trial of radiation with or without oral and intravesical misonidazole for bladder cancer

Patients with T2 grade 3 and T3 bladder cancer were randomised to be treated with radiation alone (NO MISO) or with radiation and misonidazole (PLUS MISO). Patients in both groups initially received 40 Gy in 2 Gy fractions (5/week). Patients in the NO MISO arm received a further 20 Gy in 2 Gy fractions (5/week). Patients in the PLUS MISO arm received a further 12 Gy in 6 Gy fractions (1/week). MISO was administered orally (3.0 g m-2) and intravesically (1.0 g in 35 ml of solvent) 4 h and 2 h respectively prior to each fraction of 6 Gy. Fifty-eight patients were randomized of whom 53 are evaluable. There is a minimum follow-up of 5 years in the surviving patients. In the NO MISO and PLUS MISO arms, the complete response rate at cystoscopy at 6 months was 63% and 69%, the 5-year survival rate was 41% and 48% and the 5-year local control rate with bladder preservation was 46% and 36% respectively (censored for death from metastases while locally clear). These differences are not statistically significant. Two patients had grade 3 RTOG late bowel complications. Both patients were in the PLUS MISO arm, had undergone salvage cystectomy and subsequently required colostomies for bowel obstruction for a 5-year late complication rate (RTOG grade 3) of 9%. In addition, two patients in the PLUS MISO arm developed wound sepsis post cystectomy. We were not able to demonstrate improved results from the use of oral and intravesical MISO in this study. The number of patients entered are relatively low and large differences would have been required to be detected with a power of 0.80. The use of an unconventional radiation fractionation schedule may have resulted in increased bowel morbidity in patients in the PLUS MISO arm who subsequently underwent cystectomy.

Radical radiation and oral and intra-vesical misonidazole for bladder cancer

Patients with T2 grade 3 and T3 bladder cancer were entered into studies to evaluate the efficacy of 40 Gy in 2 Gy fractions (5/week) to the whole pelvis followed by 12 Gy in 6 Gy fractions (1/week) to a coned down volume plus oral and intravesical misonidazole (MISO). In a pilot study of 22 patients the complete response rate at cystoscopy at 6 months was 73% and the 5-year survival rate (life-table) with and without bladder preservation was 48% and 54% respectively. The 5-year bowel major complication rate (life-table method) was 8%. These results are statistically significantly improved over that seen in a series of historical controls. A prospective randomized trial has been completed comparing the above regimen with 40 Gy to the whole pelvis followed by 20 Gy to the coned down volume in 2 Gy fractions (5/week). Fifty-eight patients were entered and 53 are evaluable. The complete response rate at cystoscopy at 6 months is 69% (18/26) in the patients treated with MISO and 63% (17/27) in those treated without MISO. As this is an important prognostic indicator, it is unlikely that there will be an advantage in either group and this is supported by the initial follow-up data. The complete response rate at cystoscopy at 6 months is higher in both arms of this study than in the historical series.

Chemical sensitizers for hypoxic cells: a decade of experience in clinical radiotherapy

The clinical work with chemical agents to restore the radiosensitivity of hypoxic cells began in 1973 with metronidazole, misonidazole was first given in 1974. The results so far recorded of the clinical trials with misonidazole have been generally disappointing. Only in 5 of 32 studies analyzed have significant benefits been shown to suggest real advantage with the use of misonidazole. Hypoxic cells must exist in all human tumours presenting for treatment and it is, however, probable that the oxygen effect is an important one at all dose fractionation regimes employed in radiotherapy but, after conventional fractionated radiotherapy, hypoxia may be a reason for failure in only a proportion of cases. The most important factor underlying the failure of misonidazole to achieve useful advantage is undoubtedly the low radiosensitizing concentrations achievable with the permitted dose of this neurotoxic drug. New drugs are under development and some have different dose-limiting toxicity. Those showing promise at this time are the Stanford compound, SR-2508, which is being extensively studied in the United States and the Roche compound, Ro 03-8799, which is being studied in the United Kingdom. It is possible that the greatest sensitization with the greatest tolerance will be achieved by a combination of drugs.