74 yo F with Stage IE NK/T Cell Lymphoma with involvement of the nasal cavity and paranasal sinuses presenting for radiation following 2 cycles of p-GEMOX/pembrolizumab, with planned adjuvant chemo following RT.

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Technique: VMAT based planning with daily IGRT using CBCT.

Dose: 50.4 Gy in 28 fractions.

Simulation:

  • Supine, arms down, with custom thermoplastic head and shoulder mask and custom head cushion.
  • H&N CT with IVC fused with pre-chemo PET/CT.

 

Case contributed by UCSD

Contours based on the 2021 ILROG Risk-Adapted Guidelines for NK/T-Cell Lymphoma (Qi IJROBP 2021).

GTV: The sum of involvement on clinical exam, endoscopy and imaging (CT, PET/CT) before treatment.

  • In this patient that included the anterior nasal cavity, septum, L medial maxillary sinus and anterior L nares

CTV: GTV + 5 mm + entirety of involved structures + high risk structures. Prophylactic nodal irradiation is not necessary for Stage I and IE NKTCL.

  • Primary nasal cavity NKTCL CTV includes entire nasal cavity, ipsilateral maxillary wall, anterior ethmoid sinuses, hard palate, posterior nasal aperture.
  • Entire L maxillary sinus and L facial subcutaneous tissue covered in our patient due to involvement (Stage IE).
  • Entire nasopharynx not routninely covered unless there is extension to posterior nasal apterture or nasopharynx invasion.

PTV: CTV + 3 mm, cropped off skin except in areas of CTV extention to or within 3mm of skin.

  • The Ann Arbor staging system remains the most important prognostic factor in NKTCL.
  • The ES-NRI can aid with stratification in early stage disease to assess who can benefit from chemotherapy or be treated with RT alone.
  • Our patient had three risk factors on ES-NRI (age > 60, elevated LDH, primary tumor invasion).
  • Treating to a dose of at least 50 Gy is appropriate for patients who achieve a CR after initial chemotherapy, <50 Gy can have failure rates as high as 35.5%.
  • A boost of 5-10 Gy is recommended for residual disease.
  • If using concurrent chemotherapy a dose of 45 Gy can be used.