PROLIFERATIVE POTENTIAL AND PROGNOSTIC EVALUATION OF LOW-GRADE ASTROCYTOMAS

Despite their histological similarity, low-grade astrocytomas vary wid ely in their clinical behavior. To elucidate this variable behavior, w e measured the proliferative potential of 69 primary and 18 recurrent low-grade astrocytomas and correlated the results with the clinical ch aracteristics and outcome. Each patient received an intravenous infusi on of bromodeoxyuridine (BUdR); BUdR-labeled nuclei in excised tumor s pecimens were identified by immunoperoxidase staining. The BUdR labeli ng index (LI), or S-phase fraction, ranged from < 1 to 9.3%; the LI wa s < 1% in 64 (74%) patients and greater than or equal to 1% in 23 pati ents (26%). The LI did not appear to be associated with age, sex, tumo r location, or whether the tumor was primary or recurrent. A Cox propo rtional-hazards analysis of the influence of the LI and other variable s (age, sex, tumor location, extent of surgery, primary versus recurre nt tumor) on survival showed that the LI and extent of surgery (total resection, subtotal resection, biopsy) were significant in predicting both survival and progression-free survival for all patients and for p atients with primary tumors. The LI was also significant in predicting progression-free survival for patients with recurrent tumors. The cor relation between the BUdR LI and both survival and time to recurrence suggests that the outcome of low-grade astrocytomas varies according t o the proliferative potential. The growth rate of these histologically similar tumors should be assessed individually in order to select spe cific treatment.