VARIATIONS IN TUMOR LEVELS OF CISPLATINUM THROUGH A COURSE OF FRACTIONATED RADIOTHERAPY IN PATIENTS WITH NONSMALL 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 no n-operable non-small-cell lung cancer (NSCLC). Patients and Methods: T hirty patients were treated with radiotherapy consisting of 15 fractio ns 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 iv a bolus of 6 mg/m(2) 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 procedu re was carried out on a different group of 2 patients at each of the 1 5 radiotherapy fractions, The amount of platinum in the biopsy sample was measured by atomic absorption spectroscopy and expressed as ng pla tinum/mg tissue, In another 13 patients, a biopsy was taken before beg inning the radiotherapy, and they served as controls, Results: The qua ntity of platinum/g of tissue in the patients was 11 +/- 4.4 ng/mg tis sue, During the course of fractionated radiotherapy, the quantity of p latinum/g of tumor varied considerably between radiotherapy fractions. Maximum uptake was at fractions 8 and 9 (92 ng platinum/mg tissue) wi th the minima during the first few fractions and at fractions 10, 11 a nd 12 (an average 20 ng platinum/mg tissue), Conclusions: The cyclical variations in the uptake of CDDP by the tumor tissue during the protr acted course of fractionated radiotherapy are probably due to the well -known effects of radiation on vascular function and capillary permeab ility:The results may have implications for future clinical protocols involving chemo-and radiotherapy for the treatment of the disease.