Page 27 - ITPS-8-2

INNOSC Theranostics and
Pharmacological Sciences The biochemical and biophysical guide for photodynamic therapy

is more effective when combined with other therapies, PDT is especially useful in the treatment of Barrett’s
such as photothermal therapy, which generates additional esophagus, a condition in which the epithelial cells in the
oxidative stress. The effectiveness of PDT in alleviating lower esophagus are affected, often as a result of chronic
tumor burden in patients with unresectable localized reflux of gastric contents into the esophagus. This condition
PCa has been demonstrated in several clinical trials, causes damage to the esophageal epithelial cells, leading
with relatively few complications. Despite promising pre- them to resemble those of the stomach, a process known as
clinical data showing enhanced efficacy of NP-based PSs metaplasia. While most cases of Barrett’s esophagus do not
compared to conventional PSs, their clinical application progress to cancer, individuals with this condition have an
in the treatment of PCa remains challenging. This increased risk of developing esophageal cancer. Treatment
limitation is due to the ongoing refinement of these typically involves controlling acid reflux symptoms and
compounds’ functionalities and the lack of research on monitoring the esophagus for signs of malignant changes.
clinically relevant models. PDT was the first approved as However, when cancerous transformations occur in
an endoscopic procedure for esophageal cancer in both the Barrett’s esophagus, PDT is considered. PDT can be used
United States and Japan. Initially, it was used as a palliative to eliminate cancerous or altered cells, but treatment must
local treatment for patients with obstructed esophageal be tailored to the individual case by a physician specialized
cancer. PDT is also indicated as eradication therapy for in this type of therapy. The suitability of PDT for treating
dysplastic Barrett’s esophagus, a precursor to esophageal Barrett’s esophagus depends on various factors, including
adenocarcinoma, and is supported by level 1 evidence. In the severity of the changes and the patient’s overall health.
Japan, PDT has been approved as a curative treatment for One study examined the effects of Photofrin in
superficial esophageal cancer lesions that are difficult to 77 patients with unresectable, obstructive esophageal
manage with endoscopic resection. In addition, PDT using 12
second-generation PSs has been approved for treating early cancer. Patients were initially administered Photofrin
at a dose of 1.5 – 2.0 mg/kg, followed by endoscopic
local recurrence following radiotherapy, a condition that treatment with 630 nm light 48 h later. The most common
is challenging to treat using other methods. PDT has also complications following PDT were minor, including
been evaluated in other gastrointestinal cancers, including
gastric cancer, cholangiocarcinoma, and PCa. 11 esophageal stenosis, esophagitis, pleural effusion, and
sunburn. Twenty-nine patients required more than one
5.2. Treatment of esophageal cancer using PDT cycle of PDT, and an additional seven patients required the
implantation of an expandable metal stent due to recurrent
Esophageal cancer is associated with a very poor prognosis, dysphagia. The study concluded that PDT is a safe and
with a 5-year survival rate of only 12.5%. The standard effective treatment for alleviating obstruction and bleeding
treatment for this cancer has traditionally been the in esophageal cancer.
resection of part of the esophagus; however, due to the high
morbidity associated with surgery, less invasive methods In the subsequent study, patients with advanced
such as endoscopic mucosal resection (EMR), coagulation, esophageal cancer were randomized to receive either PDT
and PDT are increasingly used. In PDT, the light source using sodium porfimer and an argon laser dye, or laser
required for this method is provided by diffusers, which are therapy using a neodymium-doped yttrium aluminum
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cylindrical and highly flexible. These diffusers are positioned garnet (Nd: YAG) laser. A total of 236 patients were
near the tumor site using an endoscope. To protect healthy randomized, and 218 were treated at 24 sites. Dysphagia
esophageal tissue, a balloon is inflated next to the diffuser. improved equally in both groups, with nine complete
Initial studies focused on using PDT as a palliative treatment tumor responses occurring after PDT and two after
for obstructive tumors, although it has also proven effective Nd: YAG therapy. Better outcomes were observed in
for treating superficial lesions. The type of PS used is a key patients whose tumors were located in the upper and lower
factor determining the treatment’s effectiveness. When thirds of the esophagus, as well as in patients with longer
sodium porfimer was used, the complete response rate was tumors or those who had previously undergone treatment.
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87%, and similar results were achieved with mTHPBC. Compared to the Nd: YAG, PDT patients experienced
Despite the high efficacy of PDT in treating esophageal more mild-to-moderate complications, including sunburn.
cancer, the method is not without undesirable side effects. In addition, treatment discontinuation occurred in only
The most frequently recorded symptoms included transient 3% of patients after PDT, compared to 19% after Nd: YAG,
skin photosensitivity, fistula stenosis, and perforation, primarily due to side effects. PDT with sodium porfimer
particularly when red light was used. However, when green demonstrated overall equivalent efficacy in alleviating
light was employed, these side effects were not observed, dysphagia in esophageal cancer compared to Nd: YAG
and the effectiveness of the therapy remained unchanged. laser thermal ablation, with an objective tumor response

Volume 8 Issue 2 (2025) 21 doi: 10.36922/itps.4559