PURPOSE: To quantify the oral mucosal cell density and proliferation rate during conventional radiotherapy of head-and-neck tumors and to compare these parameters with clinical scoring of oral mucositis. MATERIALS AND METHODS: Between 1996 and 1999, 22 patients were included in this study. Mucosal biopsies were taken before or during the radiotherapy course (5 x 2 Gy/wk). Biopsies were incubated in vitro with tritiated thymidine immediately after excision to label DNA-synthesizing cells. RESULTS: Epithelial cell density followed a biphasic radiation response. A steep decrease to about 50% of the preirradiation value (1000 cells/mm epithelium) during Week 1 was followed by a more gradual loss to about 400 cells at the end of treatment. The initial phase was based on the depression of proliferation, with 5-10 labeled cells/mm at the end of Week 1 vs. 60 labeled cells/mm in controls. Subsequently, proliferation was partially restituted at 20 labeled cells/mm. A significant difference in cell numbers was seen between Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer Grade 0 (approximately 850 cell/mm) and Grade 2 (325/mm) or Grade 3 (370/mm). No significant differences were observed between reaction grades 1, 2, and 3. CONCLUSION: Conventionally fractionated radiotherapy induces a rapid suppression in cell production in Week 1, which results in a prompt reduction in cell numbers. Subsequently, a partial restoration of proliferation significantly reduces the rate of cell loss. These processes clearly precede the clinical response. Regeneration, defined as restoration of cellularity, is already under way when the maximal clinical response is observed. Clinical reaction grading corresponds poorly to cellular density measures during conventional fractionation.
PURPOSE: To quantify the oral mucosal cell density and proliferation rate during conventional radiotherapy of head-and-neck tumors and to compare these parameters with clinical scoring of oral mucositis. MATERIALS AND METHODS: Between 1996 and 1999, 22 patients were included in this study. Mucosal biopsies were taken before or during the radiotherapy course (5 x 2 Gy/wk). Biopsies were incubated in vitro with tritiated thymidine immediately after excision to label DNA-synthesizing cells. RESULTS: Epithelial cell density followed a biphasic radiation response. A steep decrease to about 50% of the preirradiation value (1000 cells/mm epithelium) during Week 1 was followed by a more gradual loss to about 400 cells at the end of treatment. The initial phase was based on the depression of proliferation, with 5-10 labeled cells/mm at the end of Week 1 vs. 60 labeled cells/mm in controls. Subsequently, proliferation was partially restituted at 20 labeled cells/mm. A significant difference in cell numbers was seen between Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer Grade 0 (approximately 850 cell/mm) and Grade 2 (325/mm) or Grade 3 (370/mm). No significant differences were observed between reaction grades 1, 2, and 3. CONCLUSION: Conventionally fractionated radiotherapy induces a rapid suppression in cell production in Week 1, which results in a prompt reduction in cell numbers. Subsequently, a partial restoration of proliferation significantly reduces the rate of cell loss. These processes clearly precede the clinical response. Regeneration, defined as restoration of cellularity, is already under way when the maximal clinical response is observed. Clinical reaction grading corresponds poorly to cellular density measures during conventional fractionation.
Authors: Tine De Ryck; Annouchka Van Impe; Barbara W Vanhoecke; Arne Heyerick; Luc Vakaet; Wilfried De Neve; Doreen Müller; Margret Schmidt; Wolfgang Dörr; Marc E Bracke Journal: Strahlenther Onkol Date: 2014-11-29 Impact factor: 3.621
Authors: Andrea Hille; Susanne Grüger; Hans Christiansen; Hendrik A Wolff; Beate Volkmer; Jörg Lehmann; Wolfgang Dörr; Margret Rave-Fränk Journal: Radiat Environ Biophys Date: 2010-03-07 Impact factor: 1.925