ESTRO 2021 Abstract Book

S1229

ESTRO 2021

CASE

1

2

3

4

5

6

7

8

9

AGE

85

50

29

70

58

58

70

50

55

SEX

F

M

F

F

M

F

M

M

M

HISTOLOGY

B1

B1

B1

B1/2

B1

B2

B1

B1

B2/3

MASAOKA STAGE

IVB

IVA

IIB

IIIB

III

IVA

IVA

IIIA

IVA

NEOADJ CT (Etoposide, Cisplatin, Epirubicin)

-

x4

x4

x3

-

x6

-

x3

x3

SURGERY (month/year)

11/ 2014

11/ 2010

05/ 2015

07/ 2017

08/ 2013

07/ 2012

09/ 1998

01/ 2018

03/ 2016

ADJ

RT

50.4/ 28

50.4/ 28

54/2 7

50/2 5

25/5

54/2 7

50/2 5

-

50/2 5

(Gy/fr)

PREVIOUS THERAPY FOR RELAPSE

Yes

No

No

Yes

Yes

Yes

Yes

Yes

Yes

Results The majority of the lesions were located in the pleura (75%), the remaining in the lungs (12.5%) or extrathoracic sites (12.5%). The mean PTV volume and diameter were respectively 26.3 cc and 3.12 cm. The SBRT treatment was delivered in 5 fractions in all cases; the mean dose was 33.75 Gy (range 30-40), and mean BED 10Gy was 58.5 Gy (range 48-72). The median follow up was 12 months (4-27). No relapse in the RT field was recorded. Three of the nine patients developed secondary pleural lesions, two of whom underwent a second SBRT session. The treatments were well tolerated, there were no acute or late toxicities due to SBRT. At the present day the local control of the treated lesions is 100%; in particular at 3 months 31,25% patients achieved a complete response (CR), 62,5% a partial response (PR), while in 6,25% of the cases the disease remained stable; at 6 months, CR and PR were reached in a rate of 56.25% and 43.75%, respectively. After 12 months, CR was recorded for 89% of the patients.

Conclusion Based on our data, SBRT might be a valid approach for recurrent thymoma due to its intrinsic radiosensitivity, overall safety, excellent local disease control and viability for multiple lesions simultaneously. Further studies need to be conducted to establish the role of SBRT for oligorecurrent thymomas.

PO-1501 A Promo from PROMO prospective registry (Pencil beam scanning Proton therapy for Moving