Drug Transporters and Multiple Drug Resistance in Pediatric Solid Tumors.

Solid tumors account for approximately 30% of all childhood cancers. Although chemotherapy has largely contributed to strongly improve the outcome of children with cancer, multidrug resistance (MDR) remains a major mechanism limiting the overall survival of patients. An increased efflux rate of the anti-neoplastic drugs from cancer cells by action of members of the ATP-binding cassette (ABC) transporters is one of the most important mechanisms of MDR. These drug transporters play a pivotal role in preserving the balance between sensitivity and resistance to anti-neoplastic drug in specific tumor cells. The functional activity of ABC transporters have been extensively studied in adults, but barely investigated in pediatric solid malignancies. Here, we provide evidence from the current literature about MDR and ABC transporters in the most common types of pediatric solid tumors, including neuroblastoma, rhabdomyosarcoma, retinoblastoma, hepatoblastoma and Wilms' tumor.