What is your radiotherapy plan for stage IVA (cT4) cervical SCC with the tumor completely obliterating the bladder trigone?

I would follow the same schedule.

After concurrent chemo RT, I would use HDR brachy with a hybrid applicator to achieve a D90 of 85 Gy or above to the HR-CTV and avoid any hotspot in the bladder wall.

Part of the bladder wall in the trigone area receives a therapeutic dose.

If the cervical tumor is completely invading the trigone (including ureteric and urethral orifices) and is still persisting in this situation after external pelvic RT, I generally don't perform brachytherapy.

I will then administer an adapted MR-based hypofractionated boost to GTV alone to approxima...

I strive to offer brachytherapy in all potentially curative cervical cases. As Dr. @Dr. First Last describes, I plan for a brachytherapy with a hybrid interstitial applicator with a D90 to CTVHr over 80 Gy. But 2 issues have forced me to offer an SBRT boost instead:

1. Tumor response leading to a larg...

I would likely opt to maximize external radiation therapy, including a generous portion of the bladder for subclinical spread (57+ Gy), and then proceed to multi-fraction image-guided brachytherapy.