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Radiotherapy Alone for Nasal Natural-Killer/T-Cell Lymphoma

Department of Radiation Oncology, Tata Memorial Hospital, Mumbai, India

To the Editor:

We read with interest the recent article by Li et al¹ and would like to make the following observations.

This excellently written article addresses the role of primary radiotherapy (RT) for the treatment of nasal natural-killer/T-cell lymphomas. Most previous studies in literature have combined B cell and T-cell lymphomas of this region, whereas many others have reported on lymphomas of the nose and nasal cavity together with those of the nasopharynx, resulting in a heterogeneous patient population.^2-5 The authors of this article have addressed this distinct clinical entity alone and have brought forward many interesting results regarding the prognostic factors and treatment. They have found a significantly higher complete response (CR) rate for primary RT (83% v 20%; P = .0001) as compared with primary chemotherapy (CT) as initial therapy; however, the CR rate after completion of therapy did not differ significantly between the RT alone or the combined-modality therapy (CMT) arms. The RT-alone group appears to have the highest CR rate (97%), followed by the RT + CT group (88%) and the CT + RT group (81%). Furthermore, there is no difference in the progression-free survival (PFS) rates between the RT alone and CMT groups (61% for both). Considering the extremely high CR rate and equivalent PFS with RT alone, it would appear reasonable to recommend this treatment modality for patients with localized disease and to reserve adjuvant chemotherapy for patients with more widespread disease. However, the authors have not mentioned whether the radiotherapy dose used in the RT-alone arm varied from that used in the CMT arm, or commented on the optimum RT dose to be used. A relatively wide range of RT doses have been used in this study (40 to 65 Gy), and it would be interesting to note whether there exists a dose-response relationship for this particularly aggressive lymphoma. The possibility that patients in the CMT arm received a lower dose, nearer to 40 Gy, and those treated with RT alone received higher doses, around 60 Gy, cannot be excluded. This may provide an alternate explanation for the apparently equivalent PFS between the RT alone and CMT groups, and also the exceptionally high CR rate in the RT alone group. The demonstration of a higher CR rate with increasing RT dose would also be an important clinical finding and should probably be addressed in future studies and analysis.

Furthermore, there is some evidence in literature that the aggressive nature and nonresponsiveness of natural killer/T-cell and T-cell lymphomas to therapy could be attributed to CD-56 expression and frequent expression of multidrug resistance (P-glycoprotein–positive) phenotype.^6,7 The authors of the present study have mentioned that immunohistochemical studies were performed on a number of markers. It would be interesting to know whether the expression of any of these markers had an impact on response to treatment or prognosis.

Authors' Disclosures of Potential Conflicts of Interest

The authors indicated no potential conflicts of interest.

REFERENCES

1. Li YX, Yao B, Jin J, et al: Radiotherapy as primary treatment for stage IE and IIE nasal natural killer/T-cell lymphoma. J Clin Oncol 24:181-189, 2006[Abstract/Free Full Text]

2. Cheung MM, Chan JK, Lau WH, 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, 1998[Abstract/Free Full Text]

3. Liang R, Todd D, Chan TK, et al: Treatment outcome and prognostic factors for primary nasal lymphoma. J Clin Oncol 13:666-670, 1995[Abstract/Free Full Text]

4. Ye YL, Zhou MH, Lu XY, et al: Nasopharyngeal and nasal malignant lymphoma: A clinicopathological study of 54 cases. Histopathology 20:511-516, 1992[Medline]

5. Yamanaka N, Harabuchi Y, Sambe S, et al: Non-Hodgkin's lymphoma of Waldeyer's ring and nasal cavity: Clinical and immunological aspects. Cancer 56:768-776, 1985[CrossRef][Medline]

6. Yamaguchi M, Kita K, Miwa H, et al: Frequent expression of P-glycoprotein/MDR1 by nasal T-cell lymphoma cells. Cancer 76:2351-1256, 1995[CrossRef][Medline]

7. Fukuda J, Yoshihara T, Arai Y, et al: Nasal NK-cell lymphoma [Japanese]. Rinsho Ketsueki 35:588-592, 1994

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• In Reply:
  Ye-Xiong Li, Bo Yao, and Jing Jin
  JCO 2006 24: 2685-2686 [Full Text]

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