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Hypofractionated preoperative radiotherapy for high risk soft tissue sarcomas in a geriatric patient population

Vlatko Potkrajcic
Vlatko Potkrajcic
, 
Frank Traub
Frank Traub
, 
Barbara Hermes
Barbara Hermes
, 
Marcus Scharpf
Marcus Scharpf
, 
Jonas Kolbenschlag
Jonas Kolbenschlag
, 
Daniel Zips
Daniel Zips
, 
Frank Paulsen
Frank Paulsen
 y 
Franziska Eckert
Franziska Eckert
   | 19 nov 2021
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Article Category: Research Article
Publicado en línea: 19 nov 2021
Páginas: 459 - 466
Recibido: 18 may 2021
Aceptado: 17 ago 2021
DOI: https://doi.org/10.2478/raon-2021-0038
© 2021 Vlatko Potkrajcic, Frank Traub, Barbara Hermes, Marcus Scharpf, Jonas Kolbenschlag, Daniel Zips, Frank Paulsen, Franziska Eckert, published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Figure 1

Example of a radiation plan for a thigh sarcoma. The 3D conventional radiotherapy plan shows a good dose coverage for the target volumes (even for this case of the largest tumour in our series with 17 cm) (A). The dose constraints for bones concerning pathologic fractures described below were kept (B).
Example of a radiation plan for a thigh sarcoma. The 3D conventional radiotherapy plan shows a good dose coverage for the target volumes (even for this case of the largest tumour in our series with 17 cm) (A). The dose constraints for bones concerning pathologic fractures described below were kept (B).

Figure 2

Starting from the equation for equivalent dose 2 Gy (EQD2) for a hypofractionated radiation regimen in 5 fractions, the quadratic equation for the single dose in five fractions corresponding to the known EQD2 was derived. Solving the quadratic equation leads to the dose per fraction for five fractions corresponding to the given EQD2 (assuming a known α/β value for tumour control or side effects in OARs, respectively). Dose per fraction for the constraints for normofractionated radiotherapy was fixed to 2 Gy, although dose per fraction varies with the number of fractions for the same total dose (e.g. 40 Gy circumferential dose would refer to a dose per fraction of 1.6 Gy for 25 fractions in preoperative radiotherapy or 1.2 Gy for postoperative radiotherapy in 33 fractions). As dose constraints for normofractionated radiotherapy normally are not corrected for number of fractions in clinical plan evaluation, they were not corrected to EQD2 for the transfer to the hypofractionated regimen. constrHFX = constraint for hypofractioanted radiotherapy. constrNFX = constraint for normofractioanted radiotherapy.
Starting from the equation for equivalent dose 2 Gy (EQD2) for a hypofractionated radiation regimen in 5 fractions, the quadratic equation for the single dose in five fractions corresponding to the known EQD2 was derived. Solving the quadratic equation leads to the dose per fraction for five fractions corresponding to the given EQD2 (assuming a known α/β value for tumour control or side effects in OARs, respectively). Dose per fraction for the constraints for normofractionated radiotherapy was fixed to 2 Gy, although dose per fraction varies with the number of fractions for the same total dose (e.g. 40 Gy circumferential dose would refer to a dose per fraction of 1.6 Gy for 25 fractions in preoperative radiotherapy or 1.2 Gy for postoperative radiotherapy in 33 fractions). As dose constraints for normofractionated radiotherapy normally are not corrected for number of fractions in clinical plan evaluation, they were not corrected to EQD2 for the transfer to the hypofractionated regimen. constrHFX = constraint for hypofractioanted radiotherapy. constrNFX = constraint for normofractioanted radiotherapy.

Figure 3

Radiation planning parameters were evaluated for seven of nine patients with sarcomas of the lower extremity. For bone constraints concerning pathologic fracture the whole femur or the whole tibia were contoured for thigh and calf sarcomas, respectively. Black bars indicate the median values, red bars indicate the assumed constraints as described in Tbl 2 and in the main text (for bone with α/β = 1.8 Gy, worst case scenario). Gross tumour volume (GTV) coverage was reached in all cases. D98 for clinical target volume (CTV) fell short in one patient with a large calf sarcoma with a CTV reaching the skin in large areas. Re-calculated dose constraints for pathologic fracture were not reached in any case.
Radiation planning parameters were evaluated for seven of nine patients with sarcomas of the lower extremity. For bone constraints concerning pathologic fracture the whole femur or the whole tibia were contoured for thigh and calf sarcomas, respectively. Black bars indicate the median values, red bars indicate the assumed constraints as described in Tbl 2 and in the main text (for bone with α/β = 1.8 Gy, worst case scenario). Gross tumour volume (GTV) coverage was reached in all cases. D98 for clinical target volume (CTV) fell short in one patient with a large calf sarcoma with a CTV reaching the skin in large areas. Re-calculated dose constraints for pathologic fracture were not reached in any case.

Dose constraints

Constraints
Bone α/β = 1.8 Gy α/β = 2.8 Gy
V40 < 64% V23.4 < 64% V24.8 < 64% [18]
Dmean < 37 Gy Dmean < 22.4 Dmean < 23.6 Gy [18]
D2 < 59 Gy D2 < 29.3 Gy D2 < 31.3 Gy [18]
Circumferential < 50 Gy Circumferential < 26.4 Gy Circumferential < 28.3 Gy Institutional standard
Soft tissue α/β = 2.0 Gy
Circumferential < 40 Gy Circumferential < 23.7 Gy Institutional standard

Patient characteristics and postoperative complications

Age at diagnosis Localisation Size [cm] Histology Grading Days to resection Resection status Postoperative complication Follow up
85 forearm 7.5 NOS 2 45 1 hematoma alive, NED
91 lower leg 5.4 NOS no surgery lost to follow up
82 thigh 7.0 myxofibrosarcoma 2–3 25 0 alive, NED
84 forearm 6.0 epitheliod myxofibrosarcoma 3 18 0 alive, NED
91 thigh 5.5 NOS 3 15 2 local and distant recurrence
79 thoracic wall 7.7 liposarcoma 2 29 0 alive, NED
80 gluteus 10.0 NOS 3 30 0 alive, NED
84 thigh 3.7 leiomyosarcoma 3 34 0 alive, NED
83 thigh 10.0 liposarcoma 3 21 1 wound healing complication local and distant recurrence
80 thigh 8.0 NOS 3 31 0 wound healing complication, seroma alive, distant recurrence lower leg, curative treatment
90 thigh 8.5 leiomyosarcoma 2 29 0 wound healing complication alive, NED
85 axilla 9.2 liposarcoma 2 31 1 alive, NED
82 thigh 17.0 liposarcoma 2 23 0 alive, NED
87 thoracic wall 5.0 NOS 3 20 0 alive, NED
82 thoracic wall 9.0 NOS 3 23 0 wound healing complication alive, NED
91 upper arm 5.2 NOS 3 31 0 recurrence distant
81 thigh 8.3 myxoid fibrosarcoma 3 31 0 alive, NED
81 upper arm 8.3 NOS 2 32 0 alive, NED
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Medicine, Clinical Medicine, Internal Medicine, Haematology, Oncology, Radiology
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