Does your treatment approach for NK/T cell lymphoma of the nasal cavity differ depending on the volume and extent of disease?

There has been a recent (2021), updated review of treatment guidelines published by ILROG which provides very detailed recommendations including some considerations about systemic therapy.

Qi et al., PMID 33581262.

They offer treatment field suggestions based on the anatomic location of the tumor, divided into 3 subgroups: nasal, non-nasal upper aerodigestive tract, and non-upper aerodigestive tract. Borrowing from their contouring section on nasal ENKTCL:

• The (pre-chemotherapy or pre-surgery) GTVs of primary tumor and lymph nodes should be fully covered in the CTV.
• For limited stage-I nasal-ENKTCL (confined to the nasal cavity without primary tumor invasion), the CTV encompasses the high-risk structures based on the frequency of involveme...

"Modern Radiation Therapy for Extranodal Lymphomas: Field and Dose Guidelines From the International Lymphoma Radiation Oncology Group" is a great resource. It can be found here: Yahalom et al., PMID 25863750.

"CTV is determined by the prechemotherapy GTV, but often the entire involved structure is included because of uncertainty about the exact extent of initial involvement. Uninvolved sinuses are not included in the CTV, and neck nodes are treated only if involved.

•PTV margin depends on immobilization, which with optimal fixation is normally 4 to 5 mm."