Rx: 45 Gy in 25 fractions to regional lymph nodes, followed by sequential boost (of 1.8 Gy x 3 fractions) to 50.4 Gy in 28 fractions to primary tumor.

Chemotherapy: Capecitabine PO 1500 mg BID concurrently with radiation.

Sim/Planning:

CT simulation with 1.5 mm slices, from carina to iliac crest, with 4D-CT motion management, abdominal compression if motion >5 mm (was not needed in this patient), in Vac-Lok and wing board, both arms up, with IV contrast and oral contrast (30 minutes ahead of time to aid bowel delineation), and NPO at least 3 hours.
Treatment-planning MRI with the sequences T2 fat suppression, T1 pre-contrast, T1 post-contrast arterial phase, T1 post-contrast venous phase, T1 post-contrast delayed phase.

Contours per Bisello Oncol Lett 2019

GTV: primary tumor defined on MRI fused with 4D-CT on each phase of the respiratory cycle.

ITV: union of GTVs across respiratory cycle phases.

CTV_5040: ITV + 1 cm, anatomically adapted.

CTV_4500: CTV_5040 + elective nodes (portal, peri-pancreatic, hepatoduodenal, para-aortic (including covering para-aortic down to the IMA, as defined in the atlas above), anatomically adapted.

This specific patient was treated using proton therapy, so no additional PTVs were generated. If photon therapy is used, 5 mm isometric expansions of the CTVs to PTVs may be considered.

MRI is the imaging modality of choice as it can best visualize the tumor mass, biliary ducts, and blood vessels. Reviewing images with radiology is suggested.
Instead of using the 4D-CT to create the ITV, you can also consider creating the GTV and then measuring the movement of the stent/fiducial to add an ITV margin.
For unresectable cholangiocarcinoma, there is evidence to support treating up to 67.5 Gy in 15 fractions (Hong J Clin Oncol 2016).
- The median dose was only 5800 cGy.
- However, with the direct involvement of bowel, a more conservative approach with conventionally fractionated 50.4 Gy may be preferred.
Evidence shows improved overall survival and local control rates in dose escalated patients (per Tao JCO 2016).
Image alignment to the biliary stent (and occasionally duodenal stent as in this case), often placed to relieve jaundice at presentation, can be extremely helpful for daily patient setup.
Suggested dose constraints:
- Large bowel < 200 cc @ 30 Gy
- Large bowel < 150 cc @ 35 Gy
- Large bowel < 20 cc @ 45 Gy
- Large bowel < 0.03 cc @ 60 Gy
- Small bowel < 200 cc @ 30 Gy
- Small bowel < 150 cc @ 35 Gy
- Small bowel < 20 cc @ 45 Gy
- Small bowel < 0.03 cc @ 55 Gy
- Duodenum < 30 cc @ 45 Gy
- Duodenum < 0.03 cc @ 55 Gy
- Heart V40 < 10%
- Kidney each V15 < 20%
- Kidney each mean < 20 Gy
- Kidneys combined V18 < 10%
- Liver V30 < 30%
- Liver mean < 20 Gy
- Stomach < 75 cc @ 45 Gy
- Stomach < 5 cc @ 50 Gy
- Stomach < 0.03 cc @ 55 Gy
- Spinal cord < 0.03 cc @ 45 Gy
- Skin < 5 cc @ 40 Gy
- Skin < 1 cc @ 60 Gy