NK / T-cell
This is a rare subtype of lymphoma which is very aggressive. It is usually extranodal (not in the lymph nodes) and presents in the nasal, nasopharynx, tonsular regions, though it can present elsewhere. It is most common in Asian populations as well as some Latin American populations. The tumour cells usually show the presence of Epstein Barr Virus.
The following is a quote from the NCI's web site.
Extranodalnatural killer (NK)-/T-cell lymphoma (nasal type) is an aggressive lymphoma marked by extensive necrosis and angioinvasion, most often presenting in extranodal sites, in particular the nasal or paranasal sinus region.[53-56] Other extranodal sites include the palate, trachea, skin, and gastrointestinal tract. Hemophagocytic syndrome may occur; historically, these tumors were considered part of lethal midline granuloma. In most cases, Epstein-Barr virus (EBV) genomes are detectable in the tumor cells and immunophenotyping shows CD56 positivity. Cases with blood and marrow involvement are considered NK-cell leukemia.
Diagnosis and prognosis
As with all other forms of lymphoma a biopsy sample is necessary for a definitive diagnosis. This type of NHL is PET avid so it will show up well on a PET scan, though the PET scan itself cannot make the diagnosis.
There is no established International Prognostic Index for NK/T-cell lymphoma as there is for other types of lymphoma. The Korean Prognostic Index (KPI) has been shown to have prognostic significance. However the IPI for Diffuse Large B-cell lymphoma has been found to be more relevant when using modern therapies. Early stage disease has an excellent prognosis for overall survival. For late stage disease overall survival remains poor.
Traditional treatments for other aggressive types of lymphoma have shown unsatisfactory results in NK/T-cell lymphoma and the overall survival has historically been significantly worse than similarly staged aggressive lymphomas. CHOP which is the mainstay treatment for aggressive lymphomas produces inferior results in NK/T-cell lymphoma.
Recent advances and newer chemotherapy combinations have shown significant improvements. The use of SMILE chemotherapy which contains L-asparaginase in particular has had significantly better results. (1) (2) (3) Similarly treatment with IMEP plus L-asparaginase achieves superior outcomes to treatment with IMEP alone (5)
In addition it has been shown that for higher risk patients, using radiation therapy before chemotherapy achieves superior results to giving radiation after chemotherapy. (4)
- Efficacy of L-asparaginase with methotrexate and dexamethasone (AspaMetDex regimen) in patients with refractory or relapsing extranodal NK/T-cell lymphoma, a phase 2 study