title: Changes in bromodeoxyuridine labeling index during radiation treatment of an experimental tumor.
abstract: Cell proliferation kinetics in a spontaneous mouse fibrosarcoma (FSaII) growing in C3H mice has been studied by in vivo pulse labeling of cells synthesizing DNA with bromodeoxyuridine (BrdUrd). A monoclonal antibody to BrdUrd and flow cytometry were used to quantify these cells. Labeling indices (LI) were measured before and after radiation. Unirradiated 10-mm tumors had a mean LI of 17.5%. After a single dose of 20 Gy there was depression of LI after 1 day followed by a rapid increase to greater than control values after 5 days. Analysis performed after five fractions showed that LI was dependent on the dose per fraction and interval between fractions. After 5 and 7 Gy/fraction LI remained similar to control values during daily fractionation but was significantly depressed after twice daily fractionation. With doses greater than 10 Gy/fraction there was marked depression of LI using both fractionation schedules. These changes in LI correlated well with changes in tumor volume after radiation. Tumors were also biopsied after 5 fractions of a 20-fraction course to see if LI would predict for tumor control. LIs of greater than or equal to 10% were associated with lack of tumor control at 90 days while all controlled tumors had a significant depression of LI. Changes in LI after radiation were a reasonable indication of the amount of repopulation occurring and might be useful in selecting patients for altered fractionation schedules.
authors.affiliation: Edwin L. Steele Laboratory of Radiation Biology, Massachusetts General Hospital, Harvard Medical School, Boston 02114.
authors.forename: J
authors.initials: J
authors.lastname: Ramsay
authors.forename: H D
authors.initials: HD
authors.lastname: Suit
authors.forename: F I
authors.initials: FI
authors.lastname: Preffer
authors.forename: R
authors.initials: R
authors.lastname: Sedlacek
mesh_terms: D000818:Animals; D001973:Bromodeoxyuridine; D002455:Cell Division / Q000528:radiation effects; D005260:Female; D005354:Fibrosarcoma / Q000473:pathology / Q000532:radiotherapy*; D005434:Flow Cytometry; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H
chemical_list: D001973:Bromodeoxyuridine