Effect of reoxygenation on hypofractionated radiotherapy of prostate cancer

Kuperman, Vadim; Lubich, Leslie M.

doi:10.1002/mp.14343

Cited by 10 publications

(12 citation statements)

References 50 publications

(101 reference statements)

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“…12 Tumor reoxygenation and heterogeneous radiosensitivities are other potentially influential effects that need dedicated consideration. [26][27][28][29] Another limitation of the presented calculations is that dose distributions encountered in the clinics are heterogeneous, and that no volume effects were considered. Equation 4 allows the computation for cases where isoeffect curves for the tumor can be associated with a certain relative isodose line t, which is not equal to the prescription dose.…”

Section: Discussionmentioning

confidence: 99%

Technical Note: Break‐even dose level for hypofractionated treatment schedules

et al. 2021

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To derive the isodose line R relative to the prescription dose below which irradiated normal tissue (NT) regions benefit from a hypofractionated schedule with an isoeffective dose to the tumor. To apply the formalism to clinical case examples. Methods: From the standard biologically effective dose (BED) equation based on the linear-quadratic (LQ) model, the BED of an NT that receives a relative proportion r of the prescribed dose per fraction for a given α/β-ratio of the tumor, (α/β) T , and NT, (α/β) NT , is derived for different treatment schedules while keeping the BED to the tumor constant. Based on this, the "break-even" isodose line R is then derived. The BED of NT regions that receive doses below R decreases for more hypofractionated treatment schedules, and hence a lower risk for NT injury is predicted in these regions. To assess the impact of a linear behavior of BED for high doses per fraction (>6 Gy), we evaluated BED also using the LQ-linear (LQ-L) model. Results:The formalism provides the equations to derive the BED of an NT as function of dose per fraction for an isoeffective dose to the tumor and the corresponding break-even isodose line R. For generic α/β-ratios of (α/β) T = 10 Gy and (α/β) NT = 3 Gy and homogeneous dose in the target, R is 30%. R is doubling for stereotactic treatments for which tumor control correlates with the maximum dose of 100% instead of the encompassing isodose line of 50%. When using the LQ-L model, the notion of a break-even dose level R remains valid up to about 20 Gy per fraction for generic α/β-ratios and D T = 2(𝛼∕𝛽). Conclusions: The formalism may be used to estimate below which relative isodose line R there will be a differential sparing of NT when increasing hypofractionation. More generally, it allows to assess changes of the therapeutic index for sets of isoeffective treatment schedules at different relative dose levels compared to a reference schedule in a compact manner.

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Section: Discussionmentioning

confidence: 99%

Technical Note: Break‐even dose level for hypofractionated treatment schedules

et al. 2021

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“…Hypoxia plays a crucial role in the tumor response to RT [ 12 ]. Oxygenated tissue is needed for radiation to induce permanent DNA damage, thus maximizing effectiveness.…”

Section: Origins Of Trimodal Therapymentioning

confidence: 99%

The evolution of rectal cancer treatment: the journey to total neoadjuvant therapy and organ preservation

Affleck¹

2022

aog

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There has been a staggering increase in the incidence of rectal cancer, drawing our attention to early detection and optimization of its medical and surgical treatment. With this review we highlight all the major trials that revolutionized rectal cancer management and improved oncologic outcomes. We present the origins of the trimodal therapy and the studies that supported the sequence of treatment. We describe the evolution in surgical management with total mesorectal excision as the standard of care, and we review the most impactful short- vs. long-course long-course radiation therapy trials. Today, the current standard of care for non-metastatic locally advanced rectal cancer includes preoperative chemoradiation with either induction or consolidation chemotherapy, total mesorectal excision and adjuvant therapy. We discuss the advent of the “watch and wait” strategy for patients who have a complete clinical response after total neoadjuvant treatment, as well as possible future directions in the treatment of locoregional disease.

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“…Later Ruggieri 6 and Ruggieri and Nahum 7 extended this approach by including two types of hypoxic cells—acutely and chronically hypoxic—in their Poisson‐based TCP model, with an added term accounting for repopulation. The role of reoxygenation of hypoxic tumor cells in hypofractionated radiotherapy of prostate cancer was also addressed recently by Kuperman and Lubich 8 …”

Section: Introductionmentioning

confidence: 96%

“…The role of reoxygenation of hypoxic tumor cells in hypofractionated radiotherapy of prostate cancer was also addressed recently by Kuperman and Lubich. 8 In 2000, Zaider and Minerbo 9 published a TCP model which accurately describes the processes of cellular birth and death during protracted treatment. The Poisson-based TCP model with added repopulation term was proved 10 to be a good approximation to the exact model of Zaider and Minerbo.…”

Section: Introductionmentioning

confidence: 99%

Theoretical investigation of the impact of different timing schemes in hypofractionated radiotherapy

et al. 2021

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This study compares the effectiveness of three fractionation schemes of equal fraction size, comprising five fractions of SBRT over 5 days, 10 days, or 15 days, respectively. Method: This comparative study is based on two tumor-control-probability (TCP) models that take into account tumor cell re-sensitization and repopulation during treatment; the Zaider-Minerbo-Stavreva (ZMS) and the Ruggieri-Nahum (RN) models. The ZMS model is further modified to include also re-sensitization according to the β mechanism of the linear-quadratic (LQ) model of cell killing. The modified version of the ZMS model is verified through fitting to the experimental data set of Fisher and Moulder. The study applies an idea used in a plan ranking methodology developed for the case when the specific values of the model parameters are not known. Results: The TCPs of the compared regimens are calculated for various values of the model parameters and for two different values of the dose per fraction. The TCPs are presented as 2-D functions of two of the model parameters for each model correspondingly. The differences between the TCPs of each of the prolonged regimens and the TCP of the every week day regimen are also calculated for each model. Conclusions: Both models predict that the prolonged regimens are superior in terms of TCP to the every week-day one for most of the studied cases; however this is shown to exist to a different degree by the two models. It is shown again to a different degree that reversed situations where the every week day schedule is better than the prolonged regimens are also possible. It is concluded that a 30% TCP difference observed in a clinical study in favor of the fifteen-day regimen is theoretically possible. However, the fifteen-day regimen is outperformed in terms of TCP by the every week day regimen in more cases than the regimen lasting ten days. Therefore the choice of a prolongation in time must be made with care.

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Effect of reoxygenation on hypofractionated radiotherapy of prostate cancer

Cited by 10 publications

References 50 publications

Technical Note: Break‐even dose level for hypofractionated treatment schedules

Technical Note: Break‐even dose level for hypofractionated treatment schedules

The evolution of rectal cancer treatment: the journey to total neoadjuvant therapy and organ preservation

Theoretical investigation of the impact of different timing schemes in hypofractionated radiotherapy

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