Pain is the predominant subjective symptom experienced during the perioperative period in pediatric patients with solid tumors. Intense pain may impede early postoperative activities and delay the recovery process. Preemptive analgesia，as a component of multimodal analgesia strategies，aims to mitigate pain by administering analgesic interventions prior to the application of a noxious stimulus. This approach seeks to diminish both peripheral and central sensitization to pain，thereby alleviating postoperative pain. Currently，while preoperative acetaminophen is widely used in adult surgeries，research is limited for its use in pediatrics. This study aims to evaluate the impact of preemptive acetaminophen on reducing postoperative pain in children with solid tumors under the mode of ERAS.

Pediatric oncology patients face unique challenges due to their distinct clinical profile. Solid tumors like neuroblastomas, teratomas, and rhabdomyosarcomas often develop in complex areas such as the retroperitoneum, pelvis, or mediastinum, where they grow invasively and can encase major blood vessels. Children typically have larger tumor-to-body size ratios than adults, necessitating more extensive surgeries and resulting in larger wounds from tumor and lymph node removal. Their poor preoperative nutrition and compromised healing abilities, due to both their disease and treatments, lead to slower wound healing and higher risk of complications.

Managing pain in pediatric cancer patients is challenging. Almost all experience pain, with over 70% facing severe pain, making it their most distressing symptom. Young children's limited cognitive abilities often lead to underreported and undertreated pain, especially after surgery. This unrelieved pain can impair breathing, hinder movement, increase infection risk, and worsen wasting. Most concerning are the potential long-term neurological effects, as significant pain in childhood may lead to lasting changes in brain structure and function.

A comprehensive meta-analysis highlights several effective preemptive analgesics, including lornoxicam, pregabalin, ibuprofen, gabapentin, and acetaminophen (APAP). APAP is particularly popular in pediatrics for its safety when properly dosed. It is quickly absorbed in the gut and metabolized in the liver, primarily by cytochrome P450 enzymes, producing a toxic intermediate, NAPQI, which is detoxified by glutathione. APAP's analgesic effects involve peripheral COX inhibition and central modulation of COX, serotonin, L-arginine/NO, endocannabinoid, and redox pathways. Preoperative APAP can prevent pain sensitization by blocking nociceptive signal transmission to the central nervous system.

APAP has proven effective for preemptive analgesia in pediatric surgeries like tonsillectomy and appendectomy, reducing pain and enhancing recovery. However, its role in pediatric oncologic surgery is unstudied, highlighting a need to explore its use in ERAS protocols for pain management in tumor resections. This study seeks to fill that gap, potentially improving perioperative pain care for these patients.

Inclusion Criteria:

• Informed Consent: Written informed consent was obtained from the parents or legal guardians of all pediatric participants.

  • Age Requirement: Patients aged >1 month (infants and children) were eligible for enrollment.

    • Diagnosis & Treatment:

      • Radiologically or pathologically confirmed solid tumors. Ⅱ.Scheduled to undergo tumor resection surgery in the Department of Pediatric Surgical Oncology, Children's Hospital Affiliated to Nanjing Medical University.

Exclusion Criteria:

• Lack of Informed Consent: Parental/guardian informed consent was not obtained. ②Allergy/Intolerance: Known hypersensitivity or contraindication to acetaminophen (paracetamol).

  • Hepatic Impairment:Alanine aminotransferase (ALT) or aspartate aminotransferase (AST) levels >3× the upper limit of normal (ULN).

    • Renal Dysfunction:Serum urea or creatinine levels exceeding the ULN. ⑤Recent Analgesic Use: Administration of any analgesic medication within 12 hours preoperatively.

      • PCA Exclusion: Patients not receiving postoperative intravenous patient-controlled analgesia (PCA).

De-identified individual participant data (including demographic, clinical, and outcome variables) collected during the trial will be made available to qualified researchers.

Data will become accessible:Starting Date: 6 months after study completion；End Date: Minimum 5 years after publication

Access to IPD requires submitting a formal research proposal (including hypothesis/analysis plan, ethical approval proof if applicable, and conflict of interest disclosure) to the investigator's email, along with a signed Data Use Agreement (DUA) prohibiting re-identification, commercial use, and redistribution.