The cause, like in many lymphomas, is unclear but it appears to  be related to the Epstein-Barr virus.   

Treatment:

The prognosis of extranodal NK/T-cell lymphoma is variable. Some patients respond well to chemotherapy such as CHOP combined with local radiation, achieving complete remission and others perish with disseminated disease despite aggressive therapy.  Some have suggested use of daunorubicin chemotherapy or integration of L-asparaginase into therapy.  Transplants also appear to have some promise in treatment.

Since this cancer is so rare, your medical team will most likely search the current medical literature such as PubMed for the  latest successful treatment strategies.  Below are two example abstracts on treatments used from the literature:

• Abstract: Early stage nasal NK/T-cell lymphoma: clinical outcome, prognostic factors, and the effect of treatment modality. Cheung MM et al., Int J Radiat Oncol Biol Phys. 2002 Sep 1; 54(1): 182-90
• Abstract: Successful Treatment of Disseminated Nasal NK/T-Cell Lymphoma Using Double Autologous Peripheral Blood Stem Cell Transplantation, Makoto Sasaki et al. International Journal of Hematology Case Report VOL 71-1.P75
• Abstract: Therapeutic outcome of extranodal NK/T-cell lymphoma initially treated with chemotherapy--result of chemotherapy in NK/T-cell lymphoma. Kim BS et al. Acta Oncol. 2003; 42(7): 779-83

Further Reading / In-Depth

Non-Hodgkin's Lymphomas, Peter M. Mauch (Editor), James O. Armitage (Editor), et al., 2004.

• Section IV: Pathology, Biology, Clinical Evaluation, and Treatment Section
  • Chapter 26: Mature Nodal and Extranodal T-Cell and Non-Hodgkin's Cell Lymphomas (including Nasal Natural Killer/T-Cell Lymphoma)

Excellent but Technical: An Illustrated Guide to Skin Lymphomas, Cerroni, Gatter, Kerl, 2nd. Ed, 2005

• Chapter 6: Other Cutaneous Cytotoxic Lymphomas
  • Extranodal NK/T-Cell Lymphoma, Nasal Type pp. 73-75

Web Resources:

• Paper on NK Cell Lymphoma by Kazuo Oghimi, International Journal of Hematology, August 2002

References:

Papers:

• Jaffe ES, Harris NL et al. WHO Classification of tumors, Tumors of Hematopoietic and lymphoid tissues, IARC Press, 2001, Chapter 7, 204-207
• Barnes L, Swerdlow S. Surgical Pathology of the Head and Neck, 2001, Marcel Dekker, Inc. New York, Vol 2, Chapter 18, 1307-1312,
• Greer GP, Kinney MC et al, T cell and NK cell lymphoproliferative disorders, Hematology, American Society of Hematology, 2001
• Yong W, Zheng W et al, Clinical characteristics and treatment of midline nasal and nasal type NK/T-cell lymphoma, Zhonghua Yi Xue Za Zhi 2001 July; 81(13): 773-5
• Cheung MM, Chan JK et al, Primary non-Hodgkin's lymphoma of the nose and nasopharynx: clinical features, tumor immunophenotype, and treatment outcome in 113 patients. J. Clin Oncol 16:70-77.