For gyn cancers receiving chemoradiation, how high can you boost grossly positive nodes with SIB if not near bowel?

SIBs of 55-57.5 Gy in 25 fractions are frequently mentioned with bowel volume constraints at this dose, but assuming there is no bowel nearby (e.g., boosting an external iliac node), should you push this higher? For instance, 65 Gy in 25 fractions would have an EQD2 near 70 at an alpha/beta of 10 compared to 56 Gy2 for 55/25.

EQ2 calculation doesn’t take time factor into account and also contributions from brachytherapy for pelvic nodes.

I typically will give a simultaneous integrated boost (SIB) of 60 Gy in 30 fractions to the pelvic and para-aortic nodal CTV, which is the PET positive GTV plus a 3 mm margin. If possible I will boost the GTV of larger gross nodes (>1 cm) to 66 Gy (2.2 Gy/fx) with no margin, if constraints can be...

Answer from: Radiation Oncologist at Academic Institution