The objective of the present clinical trial is to assess the efficacy of photodynamic therapy (PDT) employing hematoporphyrin injection in the management of recurrent or residual superficial esophageal carcinoma. The principal objective is to determine the capability of this therapeutic modality to elicit a complete response in the patient cohort under investigation.

The central research question that this study seeks to address is as follows:

What is the rate of complete response at day 28 following treatment with photodynamic therapy utilizing hematoporphyrin injection in patients suffering from recurrent or residual superficial esophageal cancer? This study is designed as a single-arm trial, devoid of a control or comparison group.

Eligible participants will meet the following criteria:

They will be adult patients, aged between 18 and 80 years, who have experienced recurrence or retention of superficial esophageal cancer subsequent to prior therapeutic interventions.

They will receive an intravenous administration of hematoporphyrin injection at a dosage of 3mg/kg over a duration of 60 minutes.

They will undergo irradiation with a 630nm laser, which will be administered 48-72 hours post-infusion.

Their response to treatment will be evaluated at day 28 post-therapy, with assessments encompassing complete response, progression-free survival, overall survival, swallowing functionality, quality of life, and the incidence of adverse events throughout the duration of the study

Inclusion Criteria:

• 1. Age between 18 and 80 years (inclusive of both 18 and 80 years), with no restrictions on gender.

  2.Patients with esophageal squamous cell carcinoma who have undergone prior treatment, including radiotherapy, chemotherapy, immunotherapy, or surgical intervention (esophagectomy or endoscopic esophageal cancer surgery), with pathological confirmation of recurrence or residual disease (at least of high-grade intraepithelial neoplasia or above).

  3.Patients with superficial esophageal cancer, where the primary lesion is located in the mucosal or submucosal layer, and the muscular layer is still intact, as indicated by ultrasound endoscopy and related examinations.

  4.Subjects capable of tolerating general anesthesia. 5.Absence of severe hematological, coagulation, cardiac, pulmonary, hepatic, renal, or immunological abnormalities.

  6.Voluntary consent to participate in the clinical trial after being fully informed about the purpose, process, potential risks, and benefits of the trial, including the subject's obligations.

Exclusion Criteria:

1. Known allergy to the study medication or related drugs.
2. Patients who have not recovered from the toxicities associated with prior radiotherapy or chemotherapy treatments.
3. Previous treatment with other photosensitizers that was ineffective, or subjects who have received a photosensitizer treatment within 12 months prior to enrollment.
4. Use of other photosensitizing medications within 4 weeks prior to administration, such as tetracycline antibiotics, sulfonamides, and phenothiazines.
5. Neutrophil count <1.5×10^9 /L, platelet count <100×10^9 /L, or hemoglobin <100 g/L.
6. Serum creatinine ≥3 times the upper limit of normal or creatinine clearance <60 ml/min/1.73m^2; ALT or AST >3 times the upper limit of normal; or in the case of liver metastasis, ALT or AST >5 times the upper limit of normal; serum bilirubin >3 times the upper limit of normal.
7. Presence of severe comorbid conditions, including serious heart disease, cerebrovascular disease, uncontrolled diabetes, and uncontrolled hypertension.
8. HIV, HCV, syphilis infection, or positive for both hepatitis B surface antigen and e antigen.
9. Active esophageal inflammation (especially visible active ulcers, hyperemia, necrosis, etc. under endoscopy) or clinically significant active infection symptoms.
10. Pregnant or lactating women, and sexually active subjects of childbearing potential (including males) who refuse to use appropriate contraceptive measures during the study.
11. Active bleeding or bleeding diathesis (abnormal coagulation mechanism).
12. Severe physical or mental illness that may affect treatment, assessment, or compliance with the study protocol.
13. Concurrent second primary tumor undergoing treatment.
14. Single lesion greater than 5cm in length.