The tumor core boost study: A feasibility study of radical dose escalation to the central part of large tumors with an integrated boost in the palliative treatment setting

Olaf Wittenstein; Fabian Krause; Mirko Fischer; Justus Domschikowski; Mirko Nitsche; Christoph Henkenberens; Daniel Habermehl; Juergen Dunst

doi:10.1007/s00066-022-01976-5

The tumor core boost study: A feasibility study of radical dose escalation to the central part of large tumors with an integrated boost in the palliative treatment setting

Strahlenther Onkol. 2023 Mar;199(3):258-267. doi: 10.1007/s00066-022-01976-5. Epub 2022 Jul 20.

Authors

Olaf Wittenstein¹, Fabian Krause², Mirko Fischer³, Justus Domschikowski², Mirko Nitsche⁴, Christoph Henkenberens³, Daniel Habermehl⁵, Juergen Dunst²

Affiliations

¹ Department of Radiation Oncology, Universitätsklinikum Schleswig-Holstein Campus Kiel, Arnold-Heller-Straße 3, Haus L, 24105, Kiel, Germany. olaf.wittenstein@uksh.de.
² Department of Radiation Oncology, Universitätsklinikum Schleswig-Holstein Campus Kiel, Arnold-Heller-Straße 3, Haus L, 24105, Kiel, Germany.
³ Department of Radiotherapy and Special Oncology, Medical School Hannover, Hannover, Germany.
⁴ Center for Radiotherapy and Radio-oncology Bremen and Westerstede, 28239, Bremen, Germany.
⁵ Radprax MVZ, Leimbacher Str. 51a, 42281, Wuppertal, Germany.

Abstract

Purpose: For patients with large tumors palliative radiotherapy often is the only local treatment option. To prevent toxicity the administered doses are low. Dose escalation to the tumor could be an option to better smyptom control and prolong local control rates. In this prospective study we used a very pragmatic approach with a simultaneously integrated boost (SIB) to an almost geometrically defined tumor core to achieve this. The primary endpoint was to demonstrate feasibility.

Method: Patients with solid tumors > 4 cm in diameter of different histologies were eligible in this single arm, prospective, multi-institutional clinical feasibility trial with two treatment concepts: 5 × 5 Gy with an integrated boost to the tumor core of 5 × 10 Gy or 10 × 3 Gy with a boost of 10 × 6 Gy. The objective of dose escalation in this study was to deliver a minimum dose of 150% of the prescribed dose to the gross tumor volume (GTV) tumor core and to reach a maximum of at least 200% in the tumor core.

Results: In all, 21 patients at three study sites were recruited between January 2019 and November 2020 and were almost evenly spread (9 to 12) between the two concepts. The treated planning target volumes (PTV) averaged 389.42 cm³ (range 49.4-1179.6 cm³). The corresponding core volumes were 72.85 cm³ on average (range 4.21-338.3 cm³). Dose escalation to the tumor core with mean doses of 167.7-207.7% related to the nonboost prescribed isodose led to PTV mean doses of 120.5-163.3%. Treatment delivery and short-term follow-up was successful in all patients.

Conclusions: Palliative radiotherapy with SIB to the tumor core seems to be a feasible and well-tolerated treatment concept for large tumors. The applied high doses of up to 50 Gy in 5 fractions (or 60 Gy in 10 fractions) did not cause unexpected side effects in the 42 day follow-up period. Further research is needed for more information on efficacy and long-term toxicity.

Keywords: Bulky tumor; Hypofractionation; Inhomogenous dose distribution; Palliative radiotherapy; Proof of concept; SBRT.

Publication types

Clinical Trial

MeSH terms

Feasibility Studies
Humans
Neoplasms* / radiotherapy
Palliative Care
Prospective Studies
Radiotherapy Dosage
Radiotherapy Planning, Computer-Assisted
Radiotherapy, Intensity-Modulated*