Management of tumor volume changes during preoperative radiotherapy for extremity soft tissue sarcoma: a new strategy of adaptive radiotherapy

Characteristics:	n (%)
Sex
Male	12 (71)
Female	5 (29.4)
Age at initial diagnosis, years
Median (range)	69 (43–90)
Dimension, cm (diagnostic MRI)
Median (range)	12.8 (6–30)
Pathology
Undifferentiated pleomorphic sarcoma (UPS)	8 (47)
Myxoid liposarcoma (MLS)	6 (35)
Dedifferentiated liposarcoma (DLS)	2 (12)
Pleomorphic rhabdomyosarcoma (PRS)	1 (6)
Grade
1	6 (35)
2	7 (41)
3	4 (24)
RT schedule (total dose, dose fraction)
50.4 Gy, 1.8Gy	5 (29)
50 Gy, 2Gy	10 (59)
45 Gy, 3 Gy	1 (6)
70 Gy, 2 Gy*	1 (6)
GTV on CTs1 (ml)
Median (range)	381 (84–2908)
PTV on CTs1 (ml)
Median (range)	1373 (587–5793)
D95%PTV on CTs1 (%)
Median (range)	97.1 (96–99.1)
Interval between CTs1 and MVCT 1 (days)
Median (range)	13 (9–17)
Neoadjuvant CT**
No CT	10 (59)
Adriamycin ifosfamide ((doxorubicin 20 mg/m² and ifosfamide 2500 mg/m² day 1, 2 and 3 for 4 cycles (21-day cycle))	6 (35)
Adriamycin (doxorubicin 75 mg/m² day 1 for 4 cycles (21-day cycle))	1 (6)

CTs1 = CT simulation scan; D95%PTV = dose received by 95% of the PTV volume; MRI = Magnetic Resonance Imaging; MVCT1 = first fraction of RT

GTV = gross tumor volume; MVCT = megavoltage computed tomography;PTV = planned target volume; RT = radiotherapy

* Patient initially scheduled to have preoperative 50 Gy in 25 fractions but deemed inoperable, leading to a modification of the prescription.

** 6 patients received 3 cycles, 1 patient had 4 cycles

TABLE 2.

Gross tumor volume (GTV) and planned target volume (PTV) volumes variations, the largest GTV and D95% PTV changes during the course of treatment

	Pathology	Vol GTV CTs1 (ml)	Vol PTV CTs1 (ml)	Vol GTV last MVCT	Vol PTV last MVCT	Largest GTV vol change % (week)	Largest D95%PTV change % (week)
	UPS	674	1373	560	1150	+36.4 (2)	−12 (2)*
	PRS	239	1037	238	966	+33.7 (2)	−3.1 (1)
	UPS	381	1432	486	1706	+32.3 (5)	−20.1 (6)*
	UPS	2546	5292	3243	6263	+27.4 (6)	+ 1 (4)
	DLS	2908	5793	3444	6628	+18.9 (4)	−4.6 (3)
	UPS	1356	3534	1319	3446	+11 (1)	−2.1 (1)
	UPS	234	999	246	1086	+7.9 (2)	−14.1 (4)*
	UPS	140	587	144	598	−7.2 (5)	−3.4 (2)
	UPS	826	2073	781	2031	−9.2 (1)	−7.6 (4)
DLS	531	1679	461	1509	−13.2 (6)	−1.3 (3)
MLS	258	952	184	805	−28.9 (6)	−1.3 (2)
MLS	415	1514	233	1098	−43.8 (6)	+ 1.6 (6)
MLS	192	816	104	630	−46.2 (6)	−2 (6)
MLS	228	629	122	398	−46.4 (6)	+0.4 (4)
MLS	1062	3084	568	2158	−46.5 (6)	+ 1.14 (5)
UPS	208	961	96	602	−52 (6)	−0.9 (1)
MLS	84	606	44	548	−52 (5)	−7 (3)

[i] DLS = dedifferentiated liposarcoma; MLS = myxoid liposarcoma; PRS = pleomorphic rhabdomyosarcoma; UPS = undifferentiated pleomorphic sarcoma

[ii] Re-planned patients are shown in gray, patients with PTV under-coverage are marked with a star (*)

Percentage of maximal GTV changes during treatment: patients with significant gross tumor volume (GTV) increase **(A)**, patients with significant GTV decrease **(B)***. Day 0 corresponds to CTs1. Each color represents a different histology subtype; replanned patients appear as dotted line.
DLS = dedifferentiated liposarcomas; MLS = myxoid liposarcomas; PRS = pleomorphic rhabdomyosarcoma; UPS = undifferentiated pleomorphic sarcomas
* Only the largest variation is shown for patients who presented with both an increase and a decrease in tumor size during the course of treatment.

TABLE 3.

Correlations between GTV volume variations and dosimetric and clinical characteristics

		Maximal GTV change
		Decrease (n=10)	Increase (n=7)
GTV largest axial axis*	Decrease	7 (70%)	0
GTV largest axial axis*	Stable	3 (30%)	3 (43%)
Increase	0	4 (57%)
GTV largest sagittal axis*	Decrease	8 (80%)	0
GTV largest sagittal axis*	Stable	2 (20%)	3 (43%)
Increase	0	4 (57%)
Estimated GTV volume	Decrease	9 (90%)	0
Estimated GTV volume	Stable	1 (10%)	0
Increase	0	7 (100%)
PTV volume	Decrease	8 (80%)	0
PTV volume	Stable	2 (20%)	0
Increase	0	7 (100%)
D95% PTV	Decrease	0	3 (43%)
Stable	10 (100%)	4 (57%)
Surgical complications**	Yes	3 (33%)	4 (80%)
No	6 (67%)	1 (20%)
Histology subtypes	UPS	3 (30%)	5 (71%)
Histology subtypes	DLS	1 (10%)	1 (14%)
MLS	6 (60%)	0
PRS	0	1 (14%)
Histology grade	1	6 (60%)	0
Histology grade	2	2 (20%)	5 (71%)
3	2 (20%)	2 (29%)
Neoadjuvant CT	Yes	3 (30%)	4 (57%)
Neoadjuvant CT	No	7(70%)	3 (43%)

* Axial and sagittal linear tumor dimensions were recovered from the same slice for each MVCT, the slice that contained the largest tumor axial and sagittal axis on the CTs1.

** Data available for 14 patients: one patient had not been operated; the two others had not been operated when the analysis was performed.

GTV = gross tumor volume; MVCT = megavoltage computed tomography; PTV = planned target volume

TABLE 4.

Dosimetric and clinical data of patients with significant reductions in PTV coverage

Dosimetric data at first MVCT showing a variation of volume					Concomitant volume changes			Clinical dimension change*	D95% PTV on last MVCT
D95% PTV on CTs1	Fraction n°	Variation of D95 coverage (%)	New D95% PTV	D95% GTV	GTV (%)	PTV (%)	Estimated GTV(%)	Clinical dimension change*	D95% PTV on last MVCT
99%*	6*	−11.8*	87.22%*	72.96%*	+36.4*	+22.8*	+27.6*	+ 1.3 cm (ax)*	98.71%*
96.1%	6	−10.4	86.49%	98.03%	+10.7	+6.2	+12.2	+ 1 cm (sag)	77.07%
98.2%	1	−5.9	92.39%	98.91%	+2.8	+3.3	+2	No	94.29%

Significant reductions in coverage are indicated in bold. The patient who had a plan adaptation is marked with a star (*).

* The “clinical dimension change” corresponds to the largest visible variation, all slices combined.

GTV = gross tumor volume; MVCT = megavoltage computed tomography; PTV = planned target volume

TABLE 5.

Dosimetric and clinical data of patients with a plan adaptation

Dosimetric data just before plan adaptation					Evolution of D95%PTV
Clinical Reason*	Fr n°	% GTV vol change	%PTV vol change	OAR constraints	At CTs1	Before re-planning	At CTs2
Ax. increase (+ 1.3 cm)	13	+ 33	+ 22	Better	99.1%	88%	97.5%
Ax. increase (+ 0.9 cm)	4*	+ 9	+ 9	Better	98.1%	93.5%	96%
Sag. increase (+ 1.2 cm)	1	+ 23	+ 10	Better	96.8%	93.7%	95.9%
Sag. increase (+ 1 cm)	11	+ 17	+ 12	NA	96.9%	97.6%	97.6%
Ax. decrease (− 1.8 cm)	13	− 36	− 21	Bone Dm + 1.8%	96.9%	97.2%	98.7%
Sag. decrease (− 2 cm)	17	− 28	− 17	Bone Dm + 1%	96.4%	97.5%	96.5%
Weight loss	21**	− 13	− 10	Bone Dm + 30.7%	96.4%	97.1%	96.9%

Ax = axial; Bone Dm = average dose to the bone; CTs1 = CT computed tomography simulation scan; CTs2 = new Fr n° = fraction number; GTV = gross tumor volume; NA = result not available; OAR = organ at risk; PTV = planned target volume; Sag = sagittal

* The “clinical reason” data of axial and sagittal linear tumor dimensions of patients who had a plan adaptation corresponds to the largest visible variation, all slices combined.

Articles in this issue

DOI: https://doi.org/10.2478/raon-2023-0056 | Journal eISSN: 1581-3207 | Journal ISSN: 1318-2099

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Language: English

Page range: 507 - 515

Submitted on: Apr 13, 2023

Accepted on: Sep 25, 2023

Published on: Nov 30, 2023

Published by: Association of Radiology and Oncology

In partnership with: Paradigm Publishing Services

Publication frequency: 4 issues per year

Keywords:

soft tissue sarcoma,

preoperative radiotherapy,

adaptive radiotherapy,

image guided radiotherapy,

Related subjects:

© 2023 Marion Geneau De Lamarliere, Amélie Lusque, Justine Attal Khalifa, Vincent Esteyrie, Christine Chevreau, Thibaud Valentin, Dimitri Gangloff, Thomas Meresse, Louis Courtot, Philippe Rochaix, Bérénice Boulet, Eliane Graulieres, Anne Ducassou, published by Association of Radiology and Oncology
This work is licensed under the Creative Commons Attribution 4.0 License.

Volume 57 (2023): Issue 4 (December 2023)

Management of tumor volume changes during preoperative radiotherapy for extremity soft tissue sarcoma: a new strategy of adaptive radiotherapy

Figures & Tables

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FIGURE 1.

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TABLE 4.

TABLE 5.

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