Discussion
NPC, EBV-DNA-positive, mucositis, tumour, hand and foot syndrome
ADVERSE REACTIONS, HYPERPIGMENTATION, DISEASE, MUCOSITIS, TUMOUR
The PFS of metastatic NPC patients after first-line chemotherapy remains disappointing. The results of the present study suggest that for such patients, S1 MT can improve PFS and OS. Platinum-based chemotherapy is the preferred first-line treatment option for metastatic NPC (Chan et al. Screening high-risk patients who need to continue suppression of their tumour burden will help to increase the effectiveness of MT. In a retrospective study, S-1/capecitabine maintenance therapy only prolonged the OS for locoregionally advanced NPC patients in the high-risk group (Zhu et al. Because there is no consensus on the threshold for EBV-NDA positivity, the specific guidelines for EBV-DNA in MT are different. In a study conducted by Zhou et al. (Although there are few data regarding SAA in metastatic NPC, studies monitoring NPC have shown that SAA tends to increase when NPC progresses, and the decrease in SAA is associated with treatment efficacy (Chen et al. Good tolerability is an important factor for MT because of its long-term nature. As a derivative of 5-FU, S1 can cause adverse reactions that mainly include hyperpigmentation, mucositis, and hand and foot syndrome. The present study and other MT reports showed good tolerability (Zhou et al. However, the present study has several limitations. First, different first-line chemotherapy regimens might have a certain impact on the survival benefits of patients in the later stage. Although all the patients achieved disease control from the first-line chemotherapy, and the regimens were relatively uniform (the GP regimen accounted for more than 50% of cases). Second, quantified EBV-DNA and SAA might more accurately determine the population benefiting from MT. Therefore, further studies with larger sample sizes and stratified analyses will help develop better individualized MT in metastatic NPC patients. Finally, the choice of different 5-FU family drugs requires further study. Additionally, after immunotherapy has become the treatment option for metastatic NPC, PD-1 antibody as a choice strategy between maintenance treatment and oral S1/capecitabine maintenance regimen is also worthy of study.In conclusion, S1 MT can significantly improve the PFS and OS of metastatic NPC patients with a response to first-line treatment and has good tolerability. After first-line treatment, EBV-DNA-positive patients and continuously decreased SAA might benefit more from MT than EBV-DNA-negative patients and those with stable SAA.