# Combining waterlase ablation and submucosal ALA injection to enhance photodynamic therapy in early-stage oral squamous cell carcinoma: a three-patient case series

## TL;DR

This study explores a new non-surgical treatment for early-stage oral cancer using laser ablation and ALA-PDT to improve effectiveness while preserving normal tissue.

## Contribution

The novel approach combines Waterlase ablation with submucosal ALA injection to enhance ALA-PDT for early-stage oral cancer.

## Key findings

- Three patients with early-stage OSCC showed no tumor recurrence after 6 months of follow-up.
- The method preserved normal tissue and physiological functions, improving quality of life.
- Waterlase ablation helped overcome limitations of ALA-PDT by improving photosensitizer penetration.

## Abstract

Oral squamous cell carcinoma (OSCC), a common type of oral cancer, has traditionally relied on surgery or radiotherapy as the main treatment. However, these treatments often put patients at risk of deformity and speech dysfunction due to the special anatomical location of the tongue. Local 5-aminolevulinic acid photodynamic therapy (ALA-PDT) is an effective and non-invasive in situ treatment method that can treat tumors while preserving normal tissue morphology and structure. Nevertheless, the curative effect of ALA-PDT is constrained by the permeability of the photosensitizer and the penetration depth of the therapeutic laser source. This study reports three cases of early-stage well-differentiated OSCC that were managed with a nonsurgical approach. In an attempt to enhance the therapeutic effectiveness of ALA-PDT, we employed Waterlase technology to perform abrasion on the lesioned area, with the dual goals of eliminating local hyperplasia and white lesions and facilitating deeper penetration of the laser light source. Immediately following this, these patients underwent local puncture-like injections of 20% ALA. By means of this procedure, the interference caused by the epithelium on the penetration of ALA could be directly avoided. Upon completion of a 2 h incubation period, PDT was initiated at a dose of 119.4 J/cm². Before and after treatment, we evaluated the treatment effect by artificial intelligence (AI)-assisted deoxyribo nucleic acid (DNA) aneuploidy cytology by image cytometry (DNA-ICM). After 6 months of follow-up observation, these patients showed no signs of tumor recurrence. This preliminary case series suggests that Waterlase ablation-assisted submucosal ALA-PDT may provide a potential treatment alternative for early-stage OSCC. Notably, it particularly shines in the aspects of maintaining the patient’s normal physiological functions and elevating the quality of life.

All patients provided linguistically appropriate written informed consent after receiving detailed information about ALA-PDT’s therapeutic mechanisms, recurrence risks, and alternative therapies.