Hematologic complications of cancer chemotherapy.

Abstract

HE POSSIBILITY of cure or prolonged remission for many hematologic and solid neoplasms has increased greatly owing mainly to new and improved chemotherapeutic agents and various combination programs for these agents. Since most agents are not tumor specific, normal cells that are in active division and replication can be severely affected by these drugs. The organ most consistently and frequently affected by cancer chemotherapeutic agents is the bone marrow.’ In many situations, the suppression of the stem cells in the marrow or the interference with the active proliferation of a particular cell line is predictable, depending on the chemotherapeutic agent being utilized. It is such depression that guides the physician in determining the dosage and mode of administration of a particular agent or combination of agents. The bone marrow is the organ that contains the precursor populations (stem cells) for all major blood components, namely, erythrocytes, leukocytes, and platelets. In regard to the depression of bone marrow elements by chemotherapeutic agents, the kinetics of the particular cell line affected by a given drug determine the severity of the depression of that cell line.2,3 For example, the depression of red cells, giving rise to anemia, occurs much slower, regardless of the agent involved, than drug induced neutropenia because of the tremendous difference in the half-lives of these two cell lines, When one compares the half-life of the red cell (approximately 120 days) with the half-life of platelets (5 to 7 days) and with the half-life of granulocytes (6 hr), it becomes obvious why the latter two are more frequently involved in earlier suppression by chemotherapy. If a particular agent predominantly affects the stem cells rather than cells in cell cycle, then all cell lines will be suppressed. Very few classes of cancer chemotherapeutic agents, however, selectively depress the stem cell.’ Examples of these agents are the general group of nitrosoureas (carmustine or lomustine). Other classes of agents, namely, the cell-cycle agents that are not specifically phase-selective (such as the anthracyclines and certain alkylators; i.e., busulfan),