Experience in the radical radiotherapy of cancer in the bilharzial bladder: the use of misonidazole

The results of application of a protracted split-course radiotherapy regimen in T3 carcinoma in the bilharzial bladder are presented. A total dose of 70 Gy spread over 61 days was divided into four courses separated by gaps of 1, 2 and 1 week, respectively. Each of the first three sessions comprised eight fractions, 2.5 Gy each, while four such fractions were given during the fourth course. Patients were randomized between radiotherapy alone (32 patients) and radiotherapy plus misonidazole (MIS) (30 patients). The drug was given in a daily oral dose of 0.5 g/m2, 3.5 h prior to each radiation treatment. The treatment was well tolerated and MIS did not augment the radiation reaction. Mild or moderate peripheral neuropathy was experienced by 63% of patients of the group. Age and degree of upper obstructive uropathy were the most important determinants of the risk of neuropathy. The 2-year disease-free actuarial survival rates amounted to 58% and 44% in the MIS and radiotherapy alone groups respectively; the difference is not significant. The results were significantly better in case of transitional cell (67%) than squamous cell cancer (29%) but were independent of the histological grade. A strong correlation was found between the magnitude of tumour volume reduction after 40 Gy and the long-term end results.

The use of misonidazole in association with a three-fractions per day regimen in advanced head and neck epidermoid cancer. A pilot study

Twenty-one patients with Stage III or IV head and neck epidermoid cancer were treated by a three-fractions per day radiotherapy regime plus misonidazole (MIS). An initial course of 45 Gy was used, spread over 12 days and divided into 30 fractions 1.5 Gy each with a 3-hour interval between fractions. A daily MIS dose of 1 g/m2 was given 2 hours prior to the first fraction. A boost dose of 22.5 Gy/5 days was given to 10 patients, 4 weeks after the initial course, using the same fractionation scheme. The local acute and chronic reactions were acceptable. Eight patients suffered mild reversible peripheral neuropathy. The mean MIS blood level corresponded to an enhancement ratio of about 1.45. The 1-year disease-free survival rate was 9/21 and was significantly greater in patients receiving the boost irradiation. The control rate of nodal disease was encouraging. Based on this pilot study, a prospective trial is proposed aiming at testing the usefulness of MIS in MDF regimens in advanced head and neck cancer, either as the sole method of treatment or as a preoperative measure.

Misonidazole in the preoperative and radical radiotherapy of bladder cancer

Measurement of intercapillary distances suggests the presence of significant cell hypoxia in Bilharzial bladder cancer. This tumor seems to be capable of reoxygenation in view of the existence of a correlation between prognosis and immediate tumor shrinkage after irradiation. Two programs are presented: 1) Use of misonidazole with concentrated preoperative irradiation where the reoxygenation properties are not used fully. A prospective randomized study is presented whereby cystectomy alone is compared with cystectomy plus preoperative irradiation (6.5 Gy X 2F/1 week) with or without misonidazole. the drug is given either orally (in two doses 3 g/m2 each given 3.5 hours prior to each fraction; blood levels: 90-110 micrograms/ml) or intravesically. The intravesical administration is designed in the light of penetration studies and seems to have the advantage of the complete lack of systemic drug toxicity. Twenty-eight patients were included in this study and no drug toxicity was recorded. A second preoperative irradiation study is presented whereby cystectomy alone is compared with cystectomy plus preoperative irradiation (4.0 Gy X 5F) with or without misonidazole in individual doses of 2 g/m2. 2) Two radical radiotherapy regimes are presented. One protocol involves a split course (SC) protracted regime making full use of spontaneous reoxygenation. The drug is given in 0.5 g/m2 daily doses (total dose 14 g/m2 spread over 61 days, blood level: 15-20 micrograms/ml). A second protocol involves hyperfractionation stimulating continuous low-dose-rate irradiation. Higher blood levels are attained (60-80 micrograms/ml) after daily doses of 2 g/m2 (total dose: 14 g/m2 spread over 35 days). In a phase II study using SC technic, reversible grade 1 peripheral neuropathy was encountered in 5 of 22 patients. Complete tumor regression 3 months after irradiation was achieved in 18 of 22 patients with 3T tumors. No neuropathy was encountered in four patients subjected to the HF regimen who also showed complete tumor regression.