Please assess the completion status of the following clinical trial:

Trial Title: Maintenance Capecitabine Plus Best Supportive Care Versus Best Supportive Care for Metastatic Nasopharyngeal Carcinoma

Study Design Characteristics:
- Allocation: RANDOMIZED
- Intervention Model: PARALLEL
- Observational Model: None
- Primary Purpose: TREATMENT
- Time Perspective: None
- Masking: NONE
- Phase: PHASE3
- Number of Arms: 2.0

Eligibility Criteria:
Inclusion Criteria:~* Firstly diagnosed metastatic nasopharyngeal carcinoma patients~* Disease controlled after 4-6 cycles of palliative chemotherapy with taxol,cisplatin and capecitabine~* Eastern Cooperative Oncology Group (ECOG) 0-2~* Life expectation at least 12 weeks~* No systemic chemotherapy within 6 months, except for induction chemotherapy or concurrent chemotherapy~* With at least one measurable lesion~* Enough blood test~* Signed informed consent~Exclusion Criteria:~* Sever heart disease~* HIV infection~* Sever infection~* Brain metastasis, except received radical therapy 6 months ago and stable in 4 weeks~* Allogeneic organ transplantation~* Malignancy other than nasopharyngeal carcinoma, except:cervical carcinoma in situ, cured basal cell carcinoma,bladder cancer of Ta,Tis or T1, or any cured cancer for at least 3 years~* Pregnancy or breast feeding~* Difficulty in swallowing~* Received other test drugs

- Gender: ALL
- Minimum Age: 18 Years
- Maximum Age: 65 Years
- Healthy Volunteers: f

Study Arms:
- maintenance capecitabine (Type: EXPERIMENTAL): maintenance capecitabine plus best supportive care(BSC)
- best supportive care (Type: OTHER): Best supportive care and following-up every 6-8 weeks

Based on this trial design, predict the completion outcome and termination type (if applicable).