ESTRO 2024 - Abstract Book

S4128

Physics - Inter-fraction motion management and offline adaptive radiotherapy

ESTRO 2024

Simultaneous Interstitial Boost technique (SIB) was employed on the basis of PET CT ,MRI based GTV PET received 2.15Gy/ #, the GTV CT received 2Gy/# and the CTV Primary and the Elective Nodal CTV received 1.8Gy/# for 28 # in 5 1/2 wks.

The patients were assessed clinico- radiologically on day 0, 10, 20 and at completion of external beam radiotherapy by comprehensive clinical examination and Interim PET CT scans, and the response was compared and tracked.

PET CT scan and MRI of the pelvis was also done to assess the local disease status before treatment and on follow up. The patients were followed up once at the end of the first month to assess the toxicity and thereafter once in three months for a year.

Apart from the response, acute GI/GU toxicities and QOL were assessed respectively with CTCAE v 5. and EORTC QOL 24 questionnaire weekly and on every follow up.

Results:

PETCT SUV O wk

12 wk post rt

24 wk post tr

36 wk post rt

48 wks post trt

2 wk

4 wk

6 wk

1

15.7

8.4

0

0

0

0

2

18.2

13.5

0

0

0

0

3

18.2

17.5

15.3

9

4.5

4

26

7.5

0

0

0

0

0

5

10.1

7.1

2

0

0

0

0

The median follow up was 8 months and all patients completed 6 month follow up.

The clinical and the metabolic response correlated in all the patients with 2 patients having both clinical and metabolic complete responses by Day 20 & the remaining 4 patients by the end of EBRT. All patients received at least 5 cycles of concurrent chemotherapy.

All patients completed treatment within the scheduled treatment time with minimal toxicities.

Only Grade 0 or 1 Gastrointestinal/ Genitourinary and hematological toxicities were observed in all patients.

All patients had clinical Complete response and 4 out of 5 patients had radiological complete response by the end of EBRT. No treatment interruptions occurred. The On-couch time treatment time was 22 minutes (18- 28 minutes). EORTC QOL 24 Questionnaires showed a median score of 22. (18 - 28).

Conclusion:

Conclusion