Slow recruitment

• Assess responses, progression free survival (PFS) and overall survival (OS) of the combination of GIFOX-B chemotherapy with intensity-modulated radiation therapy (IMRT) in Stage IB or bulky disease - II and without IMRT in Stage III - IV.
• Assess the toxicity and maximum tolerated dose of bortezomib administered in combination with GIFOX chemotherapy.

Inclusion Criteria

1. Extranodal NK/T-cell lymphomas
2. Confirmed pathological diagnosis by the Department of Pathology SGH/NUH/TTSH.
3. Age more than or equals to 21 years.
4. Stages IB or bulky disease, II - IV
5. ECOG performance 0-2
6. Laboratory tests: ANC more than or equals to 1000/mm3, platelet more than or equals to 75,000/mm3. Creatinine less than or equals to 2x ULN or creatinine clearance more than or equals to 50 ml/min; AST and ALT less than or equals to 3x ULN. Total bilirubin < 1.5x ULN except < 3x ULN in patients with Gilbert's (as defined as > 80% unconjugated hyperbilirubinemia without other known cause); unless impairment is due to organ involvement by lymphoma.
7. Ability to understand and willingness to sign a written informed consent document.

Exclusion Criteria

1. Had prior systemic chemotherapy. Patients may be entered if they have had prior limited-field radiotherapy or a short course of glucocorticoids or single agent chemotherapy for an urgent local problem at diagnosis (e.g. epidural cord compression, superior vena caval syndrome).
2. History of peripheral neuropathy
3. HIV positive
4. Presence of CNS disease
5. Hypersensitivity to bortezomib, boron, or mannitol
6. Contraindication to any cytotoxic drug contained in the chemotherapy regimen.
7. Female subject of child-bearing potential not willing to use an acceptable method of birth control (i.e. a hormonal contraceptive, intra-uterine device, diaphragm with spermicide, condom with spermicide, or abstinence) for the duration of the study and one year beyond treatment completion.
8. Female subject pregnant or breast-feeding. Confirmation that the subject is not pregnant must be established by a negative serum β-human chorionic gonadotrophin (β-hCG) pregnancy test result obtained during screening. Pregnancy testing is not required for women without child-bearing potential.
9. Invasive or active malignancy in past 2 years.
10. Serious concomitant medical illnesses that would jeopardize the patient's ability to receive the regimen with reasonable safety.