How do you approach treatment planning for preoperative radiation therapy in gastric cancer?

If considering that it is not gastroesophageal junction, what margin do you place on the clipped GTV to formulate CTV? Is there any role for SIB to PET-avid lymph nodes? Do you do 4DCT, treat patient NPO? Any details on how preoperative chemoradiation is done would be appreciated. There do not seem to be any publicly available radiation therapy planning guidelines from TOPGEAR or CRITICS-II.

1 Answer

Mednet MemberInvited Expert

Radiation Oncology · University of Texas MD Anderson Cancer Center

Answered on

At MD Anderson, we treat nearly all gastric patients using a neoadjuvant strategy. I've outlined our approach below:

For simulation- NPO 3 hours, 4DCT

For target delineation-

iGTV (from PET, endoscopy report, etc).

Mucosal margin expansion = 3cm along the mucosal axis (sup, inf and into the uninvolved stomach but confined to mucosa). This comes from the mucosal margin the surgeons will be looking to achieve during surgery (>4cm). The 3cm mucosal margin + CTV ends up being 4cm.

Elective nodal volume = the nodes covered depends on tumor location. We generally use the same elective nodal coverage as post op. There are guidelines in the NCCN radiation details section that specify. Wo et al (https://www.practicalradonc.org/article/S1879-8500(12)...

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