In prostate cancer patients receiving EBRT, when, if ever, do you use MRI to change your seminal vesicle coverage?
For example, in standard high-risk we generally cover proximal 2cm to elective dose, before doing cone down boost to prostate and proximal 1cm.
If a tumor is localized away from the SV, would that affect your CTV?
If MRI shows SV invasion, how does that affect your CTV?
1 Answer
Mednet MemberInvited Expert
Radiation Oncology · AdventHealth Cancer Institute
Answered on
Yes! I routinely get MRI as part of planning. This obviously helps with delineation of median lobe and prostate apex, but can also show involvement of the SV.
I do not reduce elective coverage based on MRI images, because the decision to treat SV is related to risk of microscopic involvement. However, when MRI shows likely involvement, I include that tumor in my prostate CTV. I would also increase my elective dose coverage to the full SV.
When doing so, you need to be cognizant of the rectum, so in cases where anatomy is ideal, you can take this to full dose, but the rectal constraints need to trump coverage of this area that is “probable” but not confirmed disease.
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