Metronomic chemotherapy for pediatric refractory solid tumors: A retrospective single-center study

Background: Metronomic chemotherapy (MC) is based on chronic administration of chemotherapeutic agents at minimally toxic doses without prolonged drug-free breaks. MC has a multitargeted action of tumor angiogenesis inhibition and anticancer immune response stimulation and may also directly affect tumor cells to induce tumor dormancy. At our institute, MC has been introduced to treat patients with refractory/relapsed pediatric tumors. Methods: We retrospectively analyzed the data of pediatric patients with relapsed/refractory solid tumors who received treatment, including low-dose continuous administration of anti-cancer drugs. Results: Of the 18 patients, the disease statuses at the initiation of MC were complete remission ( n = 2), partial remission/stable disease ( n = 5), and progressive disease ( n = 11). The overall survival rate was 61% at 12 months and 34% at 24 months, and the progression-free survival rate was 21% at 12 and 24 months. Eleven of 18 patients, with tumor stabilization or maintained remission/stable disease, showed certain advantages in terms of overall survival rate. Even if limited to progressive disease, the survival time of responders was prolonged compared to non-responders (median 19.4 months vs. 4.7 months, P = 0.012). Conclusion: Approximately half of the patients demonstrated temporal tumor stabilization and improved survival time, although most patients had progressive disease, and MC was administered as palliative therapy. Large-scale studies on pediatric MC are rare; however, previous reports and the present study support the conclusion that MC has the potential to play an important role in pediatric cancer treatment during the advanced stage, both in terms of prolonging life and maintaining quality of life.