Combined radiotherapy and bleomycin in patients with inoperable head and neck cancer with unfavourable prognostic factors and severe symptoms.

The aim of this study was to assess the feasibility of concurrent split course radiotherapy and low-dose bleomycin in the treatment of unresectable head and neck cancer with unfavourable prognostic factors and severe symptoms. The clinical outcome of the treatment was assessed in terms of local disease control, symptom relief and toxicity. Between 1990 and 1996, 58 patients with squamous cell carcinoma of the head and neck, stage III or IV, were treated by radiotherapy (50 Gy/20 fractions) and simultaneous bleomycin (60 mg/6 fractions). Local control of disease, overall response, symptom relief and acute toxicity were evaluated. The rate of disease local control was 69% with a median response duration of 7 months (range 2-43+). The symptom relief rate was 81%. Mucositis was the prominent toxicity: G3 mucositis was reported in 27 patients. In conclusion, the treatment was feasible. A good palliation of symptoms and a good rate of local response were obtained. Moreover, toxicity was tolerable and the rate of hospitalisation was low.

Paclitaxel as a radiosensitiser: a proposed schedule of administration based on in vitro data and pharmacokinetic calculations.

Paclitaxel is efficacious against many human cancers. Because it blocks cells at the radiosensitive G2-M interface, paclitaxel has been investigated as a radiosensitiser. The results have been equivocal and somewhat contradictory. It is impossible to obtain proper pharmacokinetic calculations, aimed at obtaining maximum cytotoxicity and/or radiosensitisation, without knowing (i) how long the drug must be in contact with the cells, (ii) how long the effect lasts after the drug is removed from the cellular environment, (iii) whether the drug acts as a radiosensitiser even when, like cis-platinum, it is added after the radiation and (iv) what the minimum quantity of drug in the cellular environment is required for both chemotoxicity and radiosensitisation. The present work addresses the above questions. Two radioresistant cell lines of human origin were used, A375 melanoma and S549 lung carcinoma, in a clonogenic assay where only colonies with 50 or more cells were counted. For the irradiation, 6 MV X-rays were used. Any G2-M block was quantified by cell cycle kinetics analysis. From the results, a simulation of pharmacokinetics was conducted to calculate the schedule of administration of paclitaxel most likely to achieve and maintain significant chemotoxocity and radiosensitisation. The minimum concentration of paclitaxel for measurable cytotoxicity was 3 nM for both cell lines, but the drug was more toxic to the A549 cells. The minimum concentration for measurable radiosensitisation was 3 nM for A375 and approximately 0.1 nM for A549, but whereas above 3 nM the radiosensitivity increased in A375, it decreased above 1 nM for A549. A minimum of 18 h incubation with the drug was necessary for measurable effects and the radiosensitising effects were lost soon after its removal. There was no radiosensitisation if paclitaxel was added after the radiation, and, at the minimum effective concentrations, it caused only a minor and transient G2-M block. The pharmacokinetic calculations predict that 15 mg/m2 paclitaxel given as a 1 h infusion 5 days/week for 3 weeks during the radiotherapy should achieve both cytotoxicity and radiosensitisation. The mechanism of radiosensitisation by paclitaxel at the concentrations suggested by our results does not appear to be via a G2-M block and is probably concentration dependent. The results imply that low-dose, daily infusions of paclitaxel for as long as possible during a course of radiotherapy are more likely to result in radiosensitisation and prolonged cytotoxicity than high-dose infusions given once a week.

Variations in tumor levels of cis-platinum through a course of fractionated radiotherapy in patients with non-small cell lung cancer.

AIMS AND BACKGROUND: Radiation has been shown to affect the uptake of micromolecules by the tissues within the radiation fields. We measured tumor drug uptake throughout a course of radiotherapy for stage III non-operable non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: Thirty patients were treated with radiotherapy consisting of 15 fractions of 300 cGy given over 3 weeks. They were divided into groups of 2. At 1.5 hr before a given fraction of radiotherapy, one group was given i.v. a bolus of 6 mg/m2 CDDP (cis-diamminedichloroplatinum). Between 1.5 and 2 hr after radiotherapy, the patients underwent bronchoscopy, during which a biopsy was taken from the tumor mass. A similar procedure was carried out on a different group of 2 patients at each of the 15 radiotherapy fractions. The amount of platinum in the biopsy sample was measured by atomic absorption spectroscopy and expressed as ng platinum/mg tissue. In another 13 patients, a biopsy was taken before beginning the radiotherapy, and they served as controls. RESULTS: The quantity of platinum/g of tissue in the patients was 11 +/- 4.4 ng/mg tissue. During the course of fractionated radiotherapy, the quantity of platinum/g of tumor varied considerably between radiotherapy fractions. Maximum uptake was at fractions 8 and 9 (92 ng platinum/mg tissue) with the minima during the first few fractions and at fractions 10, 11 and 12 (an average 20 ng platinum/mg tissue). CONCLUSIONS: The cyclical variations in the uptake of CDDP by the tumor tissue during the protracted course of fractionated radiotherapy are probably due to the well-known effects of radiation on vascular function and capillary permeability. The results may have implications for future clinical protocols involving chemo- and radiotherapy for the treatment of the disease.