TUMOR TYPE IS A DETERMINANT OF SUSCEPTIBILITY TO APOPTOSIS

Little quantitative data exist on the extent of apoptosis (genetically -mediated cell deletion) in different human tumor types. Hematoxylin a nd eosin-stained paraffin sections of 102 malignant tumors (58 types) were evaluated for apoptotic cells and apoptotic bodies, using the 40X objective with a calibrated eye-piece and avoiding necrotic zones. Th e percentage of apoptotic cells and apoptotic bodies in the total numb er of tumor cells examined was designated as the apoptotic index (AI) for each case. There was a wide range in the AI for different tumor ty pes: 45 tumors had ill <1% and 93 had an AI of <7%. In 107 additional tumors (11 types), the AI was determined to be within the same low, in termediate, or high range as the index cases. Apoptotic nuclear materi al was usually more prominent than mitoses. These results suggest that each tumor type has a characteristic AI that reflects innate tumor ce ll susceptibility to undergo apoptosis. Additional data are needed to determine whether significant variations in ill correlate with altered proliferative indices, aberrant oncogene/tumor suppressor gene expres sion, and standard clinicopathologic variables.