Effectiveness of fractionated carbon ion treatments in three rat prostate tumors differing in growth rate, differentiation and hypoxia. (May 2021)

• Record Type: Journal Article
• Authors: Glowa, Christin; Peschke, Peter; Brons, Stephan; Debus, Jürgen; Karger, Christian P.
• Is Part Of: Radiotherapy and oncology. Volume 158(2021)
• Page Start: 131
• Page End: 137
• Publication Date: 2021-05
• Subjects: BED50 biological effective dose at 50% tumor control probability -- 12C-ions carbon ions -- CI confidence interval -- DF-plot Douglas-Fowler plot -- LET linear energy transfer -- LQ-model linear-quadratic model -- RBE relative biological effectiveness -- SE standard error -- SOBP Spread-out-Bragg-peak -- TCD50-value dose at 50% tumor control probability -- TD50 tolerance dose at 50% normal tissue complication probability; Carbon ion radiotherapy -- Relative biological effectiveness (RBE) -- Fractionation -- Prostate tumor -- Tumor heterogeneity; Oncology -- Periodicals; Radiotherapy -- Periodicals; Tumors -- Periodicals; Medical Oncology -- Periodicals; Neoplasms -- radiotherapy -- Periodicals; Radiotherapy -- Periodicals; Radiothérapie -- Périodiques; Cancérologie -- Périodiques; Tumeurs -- Périodiques; Electronic journals; 616.9940642
• DOI: 10.1016/j.radonc.2021.01.038
• Languages: English
• ISSNs: 0167-8140

Abstract

Highlights: Carbon ions reduce radiation response heterogeneity in fractionated treatments. Radiation response heterogeneity between and within tumor sublines is reduced. Variation of RBE with fractional dose depends on tumor differentiation. Well-differentiated tumors show the strongest fractionation effect. Results support hypofractionated carbon ion treatments for radioresistant tumors. Abstract: Purpose: To quantify the fractionation dependence of carbon ( 12 C) ions and photons in three rat prostate carcinomas differing in growth rate, differentiation and hypoxia. Material and methods: Three sublines (AT1, HI, H) of syngeneic rat prostate tumors (R3327) were treated with six fractions of either 12 C-ions or 6 MV photons. Dose-response curves were determined for the endpoint local tumor control within 300 days. The doses at 50% control probability ( TCD 50 ) and the relative biological effectiveness (RBE) of 12 C-ions were calculated and compared with the values from single and split dose studies. Results: Experimental findings for the three tumor sublines revealed (i) a comparably increased RBE (2.47–2.67), (ii) a much smaller variation of the radiation response for 12 C-ions ( TCD 50 : 35.8–43.7 Gy) than for photons ( TCD 50 : 91.3–116.6 Gy), (iii) similarly steep (AT1) or steeper (HI, H) dose–response curves for 12 C-ions than for photons, (iv) a larger fractionation effect for photons than for 12 C-ions, and (v) a steeper increase of the RBE with decreasing fractional dose for the well-differentiated H- than for the less-differentiated HI- and AT1-tumors, reflected by (vi) the smallest α / β -value for H-tumors after photon irradiation. Conclusion: 12 C-ions reduce the radiation response heterogeneity between the three tumor sublines as well as within each subline relative to photon treatments, independently of fractionation. The dose dependence of the RBE varies between tumors of different histology. The results support the use of hypofractionated carbon ion treatments in radioresistant tumors.