title: Effect of preirradiation of transplantation site on growth characteristics and hypoxic fractions in human colon tumor xenografts.
abstract: The volumetric growth curves and hypoxic fractions of seven different human colon tumor lines (clone A, clone D, WiDR, SW480, SW620, DLD-2, and HCT-8) xenografted into the flank regions of either unirradiated nude mice or mice that had received 17.5 Gy of 250-kVp X-rays 1 day prior to implantation were biomathematically analyzed using the Verhulstian equation. Significant variation was found among tumors with respect to both initial growth rates (r, days-1) and theoretical final volumes (carrying capacities, K, mm3). In radiation-damaged normal tissue, tumors grew relatively well for about the first 2 wk postimplantation, attaining volumes of about 70 to 155 mm3. Then, tumor growth rates altered. This effect varied from relatively minor effects on growth rate (tumors of clones A and D) to inhibition of growth, with actual decreases in tumor volume (e.g., WiDr, SW480, SW620, HCT-8, and DLD-2). After this short-term transience in growth kinetics, neoplasms began to steadily regrow at about 3 wk postimplantation, albeit at a slower rate than that seen in controls. Tumor bed effect values were calculated using the ratio of times at which control tumors and tumors growing in the radiation-injured tissue reached a volume of 7.5% of the K values derived from the respective control growth curves. Values for clone D, clone A, and WiDR, SW480, SW620, DLD-2, and HCT-8 tumors were, respectively, 1.89, 2.41, 3.48, 3.62, 2.82, 3.66, and 3.65, indicating that tumor bed effect responses varied by almost 100%, even for cancers of the same neoplastic class. Also, the hypoxic fractions of all tumors growing in radiation-damaged sites were increased as compared with levels in controls.
authors.affiliation: Department of Radiation Medicine, Brown University School of Medicine, Providence, Rhode Island 02912.
authors.forename: J T
authors.initials: JT
authors.lastname: Leith
authors.forename: G
authors.initials: G
authors.lastname: Padfield
authors.forename: L
authors.initials: L
authors.lastname: Quaranto
authors.forename: S
authors.initials: S
authors.lastname: Michelson
mesh_terms: D000818:Animals; D002452:Cell Count; D002455:Cell Division; D015687:Cell Hypoxia; D003110:Colonic Neoplasms / Q000473:pathology*; D006801:Humans; D008297:Male; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D011829:Radiation Dosage; D011830:Radiation Effects; D014407:Tumor Cells, Cultured