CELL-KINETICS AND THE IN-VIVO VS IN-VITRO RESPONSE OF HUMAN TUMORS TOCHEMOTHERAPY DRUGS - A COMMENTARY

The response of tumors to chemotherapy is complex. Of the many factors that affect the in vivo response to drugs, cell proliferation kinetic s and intrinsic chemosensitivity play important roles. The response of primary tumor cells to drugs in vitro is likewise complex. Data from this laboratory shows that quiescent reproductive cells from fresh tum ors are recruited into the cell cycle within the first four days of cu lture. As quiescent cells are inherently chemoresistant, their recruit ment into the cell cycle during incubation artifactually increases dru g sensitivity and complicates the interpretation of sensitivity or res istance. It is suggested that the limited positive predictive accuracy and the poor impact on survival of chemosensitivity assays may be imp roved by considering cell proliferation kinetics in the interpretation of in vitro chemosensitivity measurements.