Approved treatment — PDT: talaporfin in Japan (early lung cancer 2004, salvage treatment for esophageal cancer 2015) and 7 conditions approved by the U.S. FDA / Photoimmunotherapy: head and neck cancer in Japan (conditional early approval, insurance coverage 2021) Sources: U.S. National Cancer Institute, J Clin Med 2021, Oncotarget 2017, Cancers 2025, In Vivo 2026
The difference between photodynamic therapy and photoimmunotherapy lies in how the light-sensitive drug reaches cancer cells and how it destroys them once light is applied. Photodynamic therapy (PDT) uses a drug called a photosensitizer that produces reactive oxygen when exposed to light, while photoimmunotherapy uses an antibody that binds to a cancer-cell protein, linked to a light-sensitive dye. Both treatments are approved in Japan and covered by public insurance: PDT is used for esophageal cancer, early lung cancer and brain tumors, and photoimmunotherapy for head and neck cancer that is difficult to remove surgically.
What do the two treatments have in common?
In both treatments, a drug and light work together. A light-sensitive drug is first injected or applied, time is allowed for it to collect in the tumor, and then light such as a laser is aimed at the tumor. The drug does almost nothing on its own; the reaction happens only where light reaches, so the treated area can be kept narrow.
The U.S. National Cancer Institute (NCI) explains that light penetrates about 1 cm into tissue. Both treatments therefore suit tumors near the skin surface or in places such as the esophagus and airways, where light can be delivered through an endoscope. For deeper tumors, thin optical fibers can be placed inside the tumor to deliver light from within.
PDT vs photoimmunotherapy at a glance
| Feature | Photodynamic therapy (PDT) | Photoimmunotherapy |
|---|---|---|
| Drug structure | Photosensitizer alone (porfimer, talaporfin, aminolevulinic acid, etc.) | Cetuximab sarotalocan: the antibody cetuximab linked to the light-sensitive dye IR700 |
| How it finds cancer cells | The drug stays longer in cancer cells than in normal cells | The antibody binds directly to the EGFR protein on cancer cells |
| Light wavelength | Porfimer 630 nm, talaporfin 664 nm | 690 nm red laser |
| When light is applied | 24–72 hours later depending on the drug (NCI); 4 hours later in the talaporfin lung cancer trial | 20–28 hours after the infusion |
| How cells are destroyed | Reactive oxygen damages cancer cells and tumor blood vessels | The dye changes shape and damages the cell membrane; water flows in and the cell swells and bursts |
| Light avoidance period | About 6 weeks for porfimer; 2 weeks in the talaporfin esophageal trial | Direct sunlight for 4 weeks, or until a light test shows no reaction |
| Approved uses in Japan | Early lung cancer, esophageal cancer remaining or recurring after chemoradiotherapy, primary malignant brain tumors | Unresectable locally advanced or recurrent head and neck cancer |
Sources: U.S. National Cancer Institute / Yano T et al., J Clin Med 2021 / Okamoto I et al., Cancers 2025 / Yamakura T et al., In Vivo 2026. Light avoidance periods vary by drug and by hospital instructions.
How does PDT destroy cancer cells?
The drug used in PDT is called a photosensitizer. It spreads through the body, clears relatively quickly from normal cells and stays longer in cancer cells. When light of the right wavelength is applied, the drug reacts with oxygen to form reactive oxygen, which destroys the cancer cells. According to the NCI, PDT can also damage the blood vessels that feed the tumor and help the immune system attack cancer cells.
The U.S. FDA has approved PDT for 7 conditions: esophageal cancer, non-small cell lung cancer, basal cell skin cancer, stage 0 squamous cell skin cancer and advanced cutaneous T-cell lymphoma, together with the precancerous conditions actinic keratosis and Barrett esophagus. It is also used to relieve symptoms when cancer blocks the esophagus or airways.
In Japan, talaporfin (brand name Laserphyrin) is widely used. It was developed to clear from the body faster than the older drug porfimer, shortening the light avoidance period. Japan approved it for early lung cancer in 2004 and, in 2015, became the first country to approve it as salvage treatment for esophageal cancer remaining or recurring after chemoradiotherapy. Its use during brain tumor surgery is covered in Glioblastoma photodynamic therapy.
How does photoimmunotherapy destroy cancer cells?
A photoimmunotherapy drug combines a target-seeking antibody and a light-sensitive dye in a single molecule. Cetuximab sarotalocan (brand name Akalux), approved in Japan, links the antibody cetuximab, which binds to the EGFR protein abundant on head and neck cancer cells, to a dye called IR700. A dose of 640 mg per square meter of body surface area is infused into a vein over at least 2 hours, and a 690 nm red laser is applied 20–28 hours later.
When the dye absorbs light it changes shape and stresses the cancer cell membrane. Once the membrane is damaged, water flows into the cell, which swells and bursts. Because it targets the cancer cells the drug is bound to, it helps limit damage to surrounding normal tissue, which sets it apart from PDT. The approval history in Japan and real-world results are described in Head and neck cancer photoimmunotherapy results.
What results have patients achieved?
Studies of patients in Japan have reported good results for both treatments. Because the cancers and patient conditions differ, the figures are not compared directly.
| Treatment | Study | Patients | Reported results |
|---|---|---|---|
| Talaporfin PDT | Japanese multicenter phase 2 (Yano 2017) | 26 patients with esophageal cancer remaining or recurring locally after chemoradiotherapy or radiotherapy | Local complete response 88.5% (23 patients), no grade 3 or higher non-hematologic toxicity, no skin photosensitivity reactions |
| Talaporfin PDT | Japanese phase 2 (summarized in Yano 2021 review) | Early lung cancer | Complete response in 84.6% of evaluated lesions |
| Photoimmunotherapy | Real-world care at 3 Japanese departments (Okamoto 2025) | 40 patients with head and neck cancer difficult to treat surgically, 80 treatments in total | Response rate 75.0%, disease control 95.0%, median overall survival 26.9 months |
Sources: Yano T et al., Oncotarget 2017;8:22135–22144 / Yano T et al., J Clin Med 2021;10(13):2785 / Okamoto I et al., Cancers 2025;17(16):2671.
Kyoto University announced that the esophageal phase 2 trial achieved a high complete response rate without serious side effects. This gave patients for whom surgery after chemoradiotherapy is difficult an option that can be delivered through an endoscope. Photoimmunotherapy is likewise becoming established as a new local treatment for head and neck cancer patients who have already had surgery and radiotherapy.
How do light avoidance and side effects differ?
PDT: Because the drug briefly remains in the skin and eyes, patients avoid sunlight and bright indoor light for a period after treatment. The NCI states that this is about 6 weeks for porfimer. The American Cancer Society (ACS) notes that sunscreen cannot prevent this reaction, so long sleeves, gloves, hats and curtains are used to block light. With talaporfin the period is shorter: in the esophageal phase 2 trial, 2 weeks of light shielding led to no skin side effects, and in lung cancer studies photosensitivity resolved within 2 weeks in 84.8% of patients. Pain or swelling at the treated site and, depending on the site, cough or difficulty swallowing can occur, and most improve after treatment.
Photoimmunotherapy: According to a 2026 report by Japanese clinicians, patients avoid direct sunlight for 4 weeks after the infusion, or until a light test shows no skin reaction (usually after day 7), and long sleeves and gloves are recommended. No photosensitivity reactions occurred in the 16 treatments in that study, and the researchers concluded that photosensitivity is less frequent and milder than with conventional PDT. Side effects to watch for are pain at the treated site (92.5%, grade 3 in 12.5%) and laryngeal edema, a swelling inside the throat (42.5%). Japanese hospitals therefore prepare to secure the airway before treatment and monitor patients closely.
What decides which treatment fits?
Rather than replacing each other, the two treatments are approved for different cancers and sites. Your medical team will consider:
- Cancer type and location: whether it can be reached by endoscope, as in the esophagus or airways, or by surface light or optical fibers, as in the head and neck
- Tumor depth and size: whether light can reach the whole tumor
- Previous treatment: whether surgery or radiotherapy has already been given and is hard to repeat
- Approval scope: whether the treatment is approved in Japan for that cancer or given in a clinical trial
Some self-pay clinics in Japan advertise treatments under the name "photoimmunotherapy" that use different drugs. Even with the same name, the drug and approval status may differ, so also read Same "photoimmunotherapy" name, different treatments. Public information on photoimmunotherapy in Japan is collected in Photoimmunotherapy information.
Questions for your doctor
- Is PDT or photoimmunotherapy an approved treatment for my cancer type and location?
- Can light reach the whole tumor? Will surface illumination or optical fibers be used?
- How long must I avoid light after treatment, and what should I do at home?
- How long is the hospital stay, and how many times can the treatment be repeated?
Frequently asked questions
Are photodynamic therapy and photoimmunotherapy the same treatment?
No. Both use a drug and light, but in PDT the photosensitizer creates reactive oxygen that damages cancer cells and tumor blood vessels, while in photoimmunotherapy a dye linked to an antibody directly damages the cancer cell membrane. The drugs, light wavelengths and approved cancers are different.
How long do I need to avoid sunlight after treatment?
It depends on the drug. Porfimer PDT requires about 6 weeks, and talaporfin studies used 2 weeks of light shielding. After photoimmunotherapy, patients avoid direct sunlight for 4 weeks or until a light test shows no reaction. Follow the exact period given by your medical team.
Which cancers is photodynamic therapy used for?
In the U.S. it is approved for 7 conditions, including esophageal cancer, non-small cell lung cancer and basal cell skin cancer. In Japan, talaporfin is used for early lung cancer, esophageal cancer remaining or recurring after chemoradiotherapy, and primary malignant brain tumors.
Can photoimmunotherapy be used for cancers other than head and neck cancer?
The approved use in Japan is unresectable locally advanced or recurrent head and neck cancer. Research in other cancers is ongoing, so if you are interested, ask your medical team whether there is a clinical trial you could join.
Related: Head and neck cancer photoimmunotherapy results · FDA approves PDT for basal cell carcinoma · Glioblastoma photodynamic therapy · Photoimmunotherapy information
Sources
- National Cancer Institute — Photodynamic Therapy to Treat Cancer
cancer.gov
Checked: 2026-10-23 - American Cancer Society — Photodynamic Therapy
cancer.org
Checked: 2026-10-23 - Yano T, Minamide T, Takashima K 외. Clinical Practice of Photodynamic Therapy Using Talaporfin Sodium for Esophageal Cancer. J Clin Med 2021;10(13):2785
doi.org/10.3390/jcm10132785
Checked: 2026-10-23 - Yano T 외. A multicenter phase II study of salvage photodynamic therapy using talaporfin sodium (ME2906) and a diode laser (PNL6405EPG) for local failure after chemoradiotherapy or radiotherapy for esophageal cancer. Oncotarget 2017;8:22135–22144
doi.org/10.18632/oncotarget.14029
Checked: 2026-10-23 - Kyoto University — Japan approves photodynamic therapy for esophageal cancer after chemoradiotherapy (2015-06-30)
kyoto-u.ac.jp
Checked: 2026-10-23 - Okamoto I, Hasegawa O, Kushihashi Y 외. Real-World Effectiveness and Safety of Photoimmunotherapy for Head and Neck Cancer: A Multicenter Retrospective Study. Cancers 2025;17(16):2671
doi.org/10.3390/cancers17162671
Checked: 2026-10-23 - Yamakura T, Okamoto I, Okada T 외. Utility of a Simplified Irradiator for Photosensitivity Testing in Head and Neck Photoimmunotherapy. In Vivo 2026;40(4):2354
iv.iiarjournals.org
Checked: 2026-10-23
Written by the FTH editorial team. Sources checked 2026-10-23 · Medical review: not applicable
This article is general information based on public sources and does not replace diagnosis or treatment. Please discuss treatment decisions with your medical team.
