Rituximab Plus Chemotherapy in Recurrent/Metastatic Head and Neck Squamous Cell Carcinoma

Inclusion Criteria: 1. Histologically confirmed squamous cell carcinoma of head and neck. 2. Locoregional recurrence and/or metastases after primary curative local treatment and unsuitable for further radiotherapy and surgery; or primary distant metastases at diagnosis. 3. Measurable disease. Defined as presence of at least one lesion as being ≥10 mm in at least one dimension measured with conventional computed tomography (CT) or ≥10 mm in at least one dimension measured with spiral CT scan or magnetic resonance imaging (MRI) 4. Eastern Cooperative Oncology Group performance status ≤2; 5. Age between 20 and 65 years; and life expectancy of at least 12 weeks. 6. Prior treatments with radiation therapy for palliative management of non-target lesion metastatic disease is permitted provided that at least 2 weeks have relapsed since the last fraction of radiation therapy, disease progression has been documented and all treatment related adverse events are ≦ grade 1 at the time of registration. 7. Negative pregnancy test, Fertile patients must use effective contraception 8. No history of allergic reactions attributed to Rituximab/cisplatin/gemcitabine 9. Patient consent must be obtained Exclusion Criteria: 1. Presence of central nervous system (CNS) metastases; 2. Presence of other malignancy with the exception of curatively treated non-melanoma skin cancer or cervical carcinoma in situ prior to entry into the study 3. Presence of bone-only metastasis 4. The organ function measured within 14 days prior to study entry as defined below: White blood cell (WBC) less than 2,000/mm3, absolute neutrophil count (ANC) less than 1,500/mm3, or platelets less than 100,000/mm3; serum bilirubin greater than 1.5 times the upper limit of normal range (ULN); alanine aminotransferase (ALT) or aspartate aminotransferase (AST) greater than 2.5 times the ULN if no demonstrable liver metastases, or greater than 5 times the ULN in the presence of liver metastases; creatinine clearance ≤60 ml/min (based upon urine collection); 5. Concomitant illness including uncontrolled infection or other active, uncontrolled disease such as congestive heart failure, angina pectoris, respiratory insufficiency, and arrhythmia. 6. Documented hypersensitivity to platinum compounds or compounds of similar chemical or biologic composition 7. Pregnant or lactating women. 8. Under rituximab treatment or have ever received rituximab within six months. 9. Ongoing other concurrent investigational agents or anticancer therapy