Extranodal NK/T-Cell Lymphoma, Nasal Type (ENKL)

Epidemiology

Sex: M>F
Median Age of Onset: 50’s
Race: occur mostly in non-Caucasians
Presentation: 70-80% of cases present with limited stage (stage I or II) disease

Probable Derivation from Stage 4 NK Cells in Secondary Lymphoid Tissue
- This is distinct from Aggressive NK Cell Leukemia (ANKL) (see NK Cell Leukemia), which is believed to be derived from stage 5 NK cells in peripheral blood
- These two diseases share poor responsiveness to chemotherapy and a poor prognosis
Expression of the MDR1 Gene Product, P-Glycoprotein, on Tumor Cell Surface: P-glycoprotein actively exports many anti-tumor drugs out of the tumor cell (vincristine and doxorubicin are exported, but methotrexate and L-asparaginase are not)
- Confers resistance to typical antracycline-containing lymphoma regimens

Nasal Area: nasal origin ENKL accounts for 82% of all cases (however, nasal origin represents only 66% of stage IV cases)
Mouth/Upper Airway
- Epipharynx
- Palate
Skin: occasional origin
Soft Tissue
GI Tract
Hepatic: occasional origin
Splenic: occasional origin
Testes
Bone Marrow
- Hemophagocytic Syndrome (see Hemophagocytic Syndrome)

Poor Chemoresponsivness: 18% complete response rate
Localized ENKL
- Concurrent Chemoradiotherapy
Advanced ENKL
- Less Than or Equal to 65 y/o with Sufficient Organ Function: SMILE (Steroids + Methorexate + Ifosfamide + L-Asparaginase + Etoposide)
- Over 65 y/o or Mild Organ Damage: Dose-Reduced SMILE Regimen (66-75% Dose)
- Severe Organ Dysfunction: L-Asparaginase + Dexamethasone, Then SMILE
Relapsed/Refractory ENKL:
- Less Than or Equal to 65 y/o with Sufficient Organ Function: SMILE
- Over 65 y/o or Mild Organ Damage: Dose-Reduced SMILE Regimen (66-75% Dose)

Treatment of Advanced Extranodal NK/T-Cell Lymphoma, Nasal Type and Aggressive NK Cell Leukemia. Int J Hematol 2010; 92: 697-701 [MEDLINE]