This study is for patients with locally advanced sinonasal adenoid cystic carcinoma (SNACC), a rare and challenging cancer that tends to invade nerves and the skull base. The research aims to test a new precise treatment strategy. First, all participants will receive three sessions of "interventional chemotherapy" (transarterial chemoembolization) with the drug Epirubicin, which delivers high-dose chemotherapy directly to the tumor to shrink it as much as possible. About 4-6 weeks after the third session, doctors will use MRI scans to evaluate how well the tumor responded. Based on this response, patients will follow one of two personalized treatment paths: those whose tumors did not completely disappear will undergo surgery followed by radiotherapy; those whose tumors show complete disappearance on imaging will receive precise radiotherapy alone, potentially avoiding major surgery. This is a prospective, multicenter study. The main goals are to evaluate the safety and effectiveness of this response-adapted strategy and to see if it can improve outcomes for patients with this difficult-to-treat cancer.

1. Background and Rationale Sinonasal adenoid cystic carcinoma (SNACC) is a rare malignancy with a propensity for perineural invasion and skull base infiltration. Complete surgical resection is challenging and often associated with significant morbidity. While systemic chemotherapy offers limited benefit, our preclinical data from patient-derived tumor organoid drug sensitivity testing identified Epirubicin as the most active agent (sensitivity rate: 87.5%, n=24).Transarterial chemoembolization allows for targeted, high-dose drug delivery to the tumor bed while minimizing systemic exposure, presenting a promising neoadjuvant strategy.

2. Study Objectives

   Primary Objectives: To evaluate the objective response rate (ORR) after three cycles of transarterial Epirubicin chemoinfusion, the 2-year progression-free survival (PFS) of the integrated strategy, and the safety profile of the interventional chemotherapy.

   Secondary Objectives: To assess the complete response (CR) rate post-chemotherapy, the safety of subsequent surgery/radiotherapy, overall survival (OS), and explore biomarkers predictive of response.

3. Study Design This is a prospective, multicenter, single-arm, interventional study. The study employs a response-adapted design.

4. Methodology

   Participants: Approximately 100 patients with histologically confirmed, locally advanced (T3/T4) SNACC will be enrolled across multiple centers in China, including [Fudan University Eye & ENT Hospital].

   Intervention: All participants will receive three cycles of transarterial Epirubicin chemoinfusion (60mg/m² per cycle, q4w). Central imaging review (MRI, RECIST 1.1) will be performed 4-6 weeks after the third cycle.

   Stratified Treatment Pathways:

   Path A (Non-CR): Patients not achieving CR will undergo planned skull base surgery followed by adjuvant radiotherapy.

   Path B (CR): Patients achieving imaging CR will proceed directly to definitive intensity-modulated radiotherapy (IMRT) without surgery.

   Assessments: Efficacy will be assessed via serial contrast-enhanced MRI. Safety will be monitored per CTCAE v5.0, including laboratory tests and cardiac function evaluation (echocardiography).

   Statistical Analysis: The sample size is calculated based on demonstrating superiority in ORR compared to a historical benchmark. PFS and OS will be analyzed using the Kaplan-Meier method. Analysis will follow the intention-to-treat principle.

5. Ethics and Dissemination The study protocol has been approved by the Institutional Review Board of [Fudan University Eye & ENT Hospital] (Approval No: [2025307]). It will be conducted in accordance with the Declaration of Helsinki. Results will be disseminated through peer-reviewed publications and academic conferences.

Inclusion Criteria:

1. Age between 18 and 70 years.
2. Histologically confirmed diagnosis of sinonasal adenoid cystic carcinoma (ACC).
3. Tumor stage T3 or T4 according to the AJCC (American Joint Committee on Cancer) 8th edition staging system. Participants with lymph node metastasis must be amenable to surgical dissection. Those with distant metastasis must have stable disease.
4. Ability to provide a sufficient volume (≥0.5 cm³) of fresh tumor tissue via biopsy or surgery for research purposes, with participant's informed consent.
5. ECOG (Eastern Cooperative Oncology Group) performance status score of 0 to 2.
6. Voluntary participation and provision of written informed consent. Good compliance, able to cooperate with treatment and follow-up.

Exclusion Criteria:

1. Prior treatment with Epirubicin or any other anthracycline-based chemotherapy.
2. Prior radiotherapy to the head and neck region.
3. Administration of any other chemotherapy, targeted therapy, or immunotherapy within 4 weeks prior to study enrollment.
4. Concurrent participation in another interventional drug clinical trial.
5. Inadequate liver, kidney, or bone marrow function that does not meet the requirements for the planned treatment regimen.
6. Contraindications to anthracycline-containing chemotherapy regimens: known allergy to anthracyclines, presence of ≥ Grade 2 peripheral neuropathy, or uncontrolled nausea/vomiting or chronic gastrointestinal diseases.
7. Severe uncontrolled acute infection or decompensated major organ dysfunction.
8. Pregnancy or lactation.

This is an investigator-initiated study conducted in China. Individual participant data (IPD) contains sensitive personal health information and is subject to strict data protection regulations in China (e.g., the Personal Information Protection Law). There is currently no approved data sharing mechanism that fully complies with these regulations while ensuring participant privacy. Therefore, there is no plan to publicly share raw IPD. Aggregate results will be shared through publication in peer-reviewed journals.

This is an open-label study. The assignment to subsequent local therapy is based on objective imaging assessment (RECIST 1.1).