Initially Accelerated Fractionation of the R1H Tumor of the Rat Increases Local Tumor Control and Might Reduce Impact of Overall Treatment Time

Raabe, Annette; Petersen, Cordula; Krüll, Andreas

doi:10.1007/s00066-007-1654-9

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“…The results agree with the general front loading principle discussed in our previous publications (Sachs et al 1996, Fakir et al 2013 and corroborated by other investigators (Hanin and Zaider 2014). The principle is also consistent with animal experiments, in which accelerated radiation therapy produced higher tumor control when given at the beginning of the treatment (Beck-Bornholdt et al 1991, Raabe et al 2007. Although front boosting was the most biologically effective, spreading the boost over the first five weeks (I2 in figure 1) may be as effective except for fast growing tumors.…”

Section: Discussionsupporting

confidence: 91%

Hypo-fractionated boost in locally advanced non-small cell lung cancer: temporal distribution of boost fractions

2018

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To propose new schemas for radiation boosting of primary tumors, in locally advanced non-small cell lung cancers (NSCLC), in conjunction with standard chemoradiotherapy. To investigate the effect of temporal distributions of the boost fractions on tumor control. NSCLC cases, previously treated with 60 Gy in 30 fractions, were retrospectively planned by adding a radiation boost (25 Gy in 5 fractions) to the primary tumor. Several integrated and sequential boosting schedules were considered. Biological doses were calculated for targets and organs at risk (OAR). Tumor control probabilities (TCP) were calculated using an empirical model and a stochastic model that accounts more systematically for tumor growth kinetics and cell kill. For heterogeneous patient populations, the TCPs for different boost schedules ranged from 82% to 84% and from 73% to 74% for integrated and sequential boosting respectively. For individual tumors with specific growth parameters, the TCP varied by up to 19% between the different schedules. The TCP for sequential boosting was expected to be up to 67% lower than front integrated boosting. The gap in TCP between schedules was higher for tumors with higher clonogenic cell numbers, lower radio-sensitivity, shorter doubling times and lower cell loss. The proposed boosting schemas are dosimetrically feasible and biologically effective. We suggest that the boosts are most effective when given during the first week of treatment and least effective when given sequentially after the end of treatment. The effect of boost scheduling and the effectiveness of front boosting are expected to be most significant for tumors with high clonogenic cell numbers, fast growing rates, low cell loss and low radio-sensitivity. Ultimately, animal studies and clinical trials, guided by biology modeling as presented in the present work, will be needed to verify the effectiveness of fine tuning temporal distributions of radiotherapy fractions.

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Section: Discussionsupporting

confidence: 91%

Hypo-fractionated boost in locally advanced non-small cell lung cancer: temporal distribution of boost fractions

2018

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Initially Accelerated Fractionation of the R1H Tumor of the Rat Increases Local Tumor Control and Might Reduce Impact of Overall Treatment Time

Abstract: The results indicate that initially accelerated irradiation not only improves local tumor control but also minimizes the negative effect of treatment time prolongation. This might be due to changes in tumor cell repopulation kinetics.

Cited by 1 publication

References 20 publications

Hypo-fractionated boost in locally advanced non-small cell lung cancer: temporal distribution of boost fractions

Hypo-fractionated boost in locally advanced non-small cell lung cancer: temporal distribution of boost fractions

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