ABSTRACT

IV . Factors Influencing the Effects of Drug-Radiation Interactions ................... 16 A . Tumor and Normal Tissue Type .......................................... 16

............................................................................... References 18

I. INTRODUCTION The combined modality approach to cancer treatment is now recognized as offering the

best chances of increasing overall survival figures for many of the common "solid" tumors including those of the breast,' ovary,* and head and neck.3 Indeed, successful use of chemotherapy in conjunction with surgery andtor radiotherapy already has resulted in significantly enhanced cure rates for certain pediatric tu rnor~ ,~ testicular teratoma~,~ and small-cell lung ~ a n c e r ; ~ however, with this gradual overturning of the traditional approach, which had relegated chemotherapy to a palliative role, the optimal way of integrating chemotherapy with local therapies remains largely to be determined. In particular, the most appropriate sequencing of chemotherapy and radiation therapy is still a matter of investigation. Chemotherapy may be used initially to induce tumor regression so that smaller fields of irradiation are then possible. Chemotherapy, applied during radiation, may "sensitize" cells to radiation while also sterilizing distant subclinical disease. Chemotherapy after radiotherapy may control subclinical disease while permitting maximum initial radiotherapy to be applied with less host toxicity.