[Benign diseases in radiotherapy: a practice survey in Belgium. Peer review of radiotherapy in Belgium]. / Affections bénignes et radiothérapie: une enquête de la pratique en Belgique. Peer review de radiothérapie de Belgique.

In 1996 and 2000, a survey of radiation practice in Belgium was performed by sending a questionnaire to the different centers asking their opinion and number of patients treated. There was a great similarity between the two surveys both for indications and total number of patients irradiated. For the most common indications (prevention of cheloids, heterotopic bone formation, hyperthyroidy ophthalmopathy), there was a trend to use similar radiation technique following recent publications. In contrast, if the number of cases of macular degeneration is declining, the prevention of vessels restenosis is becoming more and more an indication.

Discrepancy between cytotoxicity and DNA interstrand crosslinking of carboplatin and cisplatin in vivo.

We used the method of alkaline elution to compare quantitatively the DNA lesions produced by cisplatin and carboplatin in the AKR leukemia in vivo. These data were compared with cytotoxicity of each drug in the same animal model and in a solid tumor murine model (colon 26). DNA-protein and DNA-DNA interstrand crosslinks were formed in similar proportions by both drugs when peak values of crosslinking were compared. No clear difference in the rate of formation of both types of crosslinks could be observed between these drugs. On a molar basis a 3- to 4-fold more carboplatin had to be given to obtain equivalent frequencies of both types of crosslinks. In contrast, to obtain equitoxicity in the same animal tumor model, 13 fold higher doses of carboplatin had to be given. This difference in cytotoxicity between both drugs is comparable to the difference measured in colon 26 in vivo (16 fold). Both values are in the range of literature data (10-25 fold) dealing with the relative potency of cisplatin and carboplatin in murine tumor models.

In vivo DNA cross-linking by cyclophosphamide: comparison of human chronic lymphatic leukemia cells with mouse L1210 leukemia and normal bone marrow cells.

Alkaline elution was done on a variety of cells following cyclophosphamide (CY) treatment in vivo. Cells used were L1210 leukemia, normal mouse bone marrow, and peripheral blood cells obtained from a patient with chronic lymphatic leukemia (CLL). Endpoints used were determination of single strand breaks, DNA-DNA interstrand and DNA-protein cross-links. After treatment of mice with CY (4 mg/mouse), low levels of single strand breaks were observed in both L1210 leukemia and CDF1 normal bone marrow. When a patient with CLL was treated with CY (750 mg/m2), no evidence of single strand breaks could be demonstrated. Maximum levels of DNA-DNA interstrand cross-links were observed in mice 2 h after injection of CY for the L1210 leukemia cells [175 +/- 25 rad-equivalents (req)] and at 4 h for the CDF1 normal bone marrow cells (47 +/- 9 req). In human CLL, maximum levels were observed 12 h after injection of CY. Peak levels of DNA-DNA interstrand cross-links were approximately 4-fold lower in CDF1 normal bone marrow cells than in L1210 leukemia. The frequencies measured in human CLL cells were relatively low at any timepoint (mean at 12 h = 36 req). Maximum levels of DNA-protein cross-links were observed 4 h after injection of CY (4 mg/mouse) for both L1210 leukemia [123 req (mean)] and normal bone marrow cells [50 req (mean)]. DNA-protein cross-links were measurable in CLL at timepoints later than 4 h after the start of injection of CY. In order to obtain equitoxicity between L1210 leukemia and CDF1 normal bone marrow cells, about 18-fold higher doses of CY had to be given than in the case of the normal bone marrow cells. In contrast, only 4-fold higher doses had to be given to the normal bone marrow to obtain equivalent peak levels of DNA-DNA interstrand cross-links.

Influence of WR2721 on DNA cross-linking by nitrogen mustard in normal mouse bone marrow and leukemia cells in vivo.

In previous studies we showed that WR2721 enhanced nitrogen mustard (HN2) cytotoxicity to AKR mouse leukemia. Simultaneously, it protected normal bone marrow from drug cytotoxicity. In this study, the method of alkaline elution was used to measure the modifications of HN2 induced DNA damage in the same animal model. In leukemia cells, no significant differences in DNA-DNA interstrand cross-links were observed between mice treated with WR2721 and HN2 and mice treated with HN2 alone. In normal bone marrow, DNA-DNA cross-linking was decreased by about 50% in mice treated by WR2721 and HN2. The difference was significant (P = 0.01). In leukemia, half-time of repair was 73 min for HN2 and 83 for WR2721 and HN2 treated mice, while in normal bone marrow, respectively, 73 and 64 min were calculated. WR2721 modulation significantly decreases DNA-protein cross-links in leukemia cells (P less than 0.05). This decrease was observed for early as well as for late DNA-protein cross-links. In normal bone marrow cells, only early DNA-protein cross-links were decreased. The meaning of this observation is unclear.

Long-term results of low dose total body irradiation for advanced non-Hodgkin lymphoma.

Sixty-eight patients received fractionated low dose total body irradiation (LTBI) as treatment for non-Hodgkin lymphoma (NHL) at the Rotterdamsch Radio-Therapeutisch Instituut (RRTI) in the period 1973-1979. Ninety percent (61/68) of these patients had advanced disease (Stage III + IV). According to current malignancy grade classifications, 34 patients had low grade NHL, 10 intermediate, and 19 high grade. In 5 cases no exact grading was possible. LTBI was given 3 times a week, midline dose 0.1 Gy, using 6 or 25 MeV photons to a mean total dose of 1.78 Gy. Initial response rate for low, intermediate, and high grade NHL was resp. 84, 42, and 40%. The main prognostic factor for survival and recurrence-free survival (RFS) was malignancy grade. Probability of uncorrected survival at 10 years for low, intermediate, and high grade was resp. 34, 0 and 0%. Probability of RFS at 10 years was resp. 19, 0, and 0%. Neither stage nor sex had any influence on survival. Age was reversely correlated with survival, but was not correlated with RFS. Influence of prior therapy (18 patients) on survival and RFS was separately analyzed. Neither survival nor RFS of unfavorable histologic type NHL (high and intermediate grade) was influenced. On the other hand patients with a favorable histologic type NHL (low grade) had a significantly (p less than 0.05) better RFS if they received LTBI as initial treatment, but survival was not significantly influenced. RFS at 5 and 10 years of patients who received LTBI as first treatment was respectively 32% and 27%. No treatment related complications were noted. Subsequent chemotherapy in case of relapse was not hampered by previous LTBI. The high response rate and extended RFS, without maintenance therapy, makes LTBI a preferable first line treatment for patients with advanced stage low grade NHL.

Pharmacokinetics of mitoxantrone in humans following single-agent infusion or intra-arterial injection therapy or combined-agent infusion therapy.

This study describes the pharmacokinetics of mitoxantrone determined by a sensitive and specific HPLC-method. The time-concentration curves of i.v.-treated patients (15 mg/m2 over 30 min) correspond to a three-compartment model with a T1/2 alpha of 12 min, a T1/2 beta of 93 min, and a slow elimination phase of 36 h. The central compartment volume was 26.22 and the distribution volume, 1381.9. The mean urinary excretion was 4.9% of the total dose. The pharmacokinetic parameters were also defined in five patients who were treated with combination chemotherapy (mitoxantrone 12 mg/m2, methotrexate 30 mg/m2 and vincristine 2 mg). These results were not different from those with the single-drug treatment, except for the volume of the central compartment, which was significantly decreased. The peak levels after hepatic arterial infusion of mitoxantrone were three times lower than those after the identical dose given i.v. to the same patient. Pleural fluid sampling showed a six-fold increase compared with the plasma level (12 ng/ml versus 2 ng/ml). A multiple linear regression analysis of the data revealed correlations between the pharmacokinetic results and some of the baseline parameters. It is possible to predict changes in the kinetic behaviour of mitoxantrone on the basis of these relations but on the other hand toxicity is less predictable from the baseline parameters or from the pharmacokinetic results.