Photodynamic therapy (PDT) for the treatment of malignant tumors is a new technology for cancer treatment that has emerged in the past 30 years. PDT has unique and irreplaceable advantages over other traditional treatments for tumors and has good synergy with surgery, radiotherapy and chemotherapy. Since June 2002, our department has treated 36 cases of malignant tumors by inter-tissue irradiation with PHOTOFRIN/DIOMED 630 PDT system, and achieved good efficacy, which is reported as follows. 1. Data and methods 1.1 Patients 36 cases of malignant tumors were admitted to our hospital, 25 were male and 11 were female, aged 26-74 years old, with an average of 52.4 years old, including 7 cases of tongue cancer, 12 cases of oropharyngeal and nasopharyngeal cancer, 1 case of basal cell carcinoma of the upper lip, 7 cases of liver cancer, 1 case of kidney cancer, 3 cases of breast cancer, and 5 cases of lung cancer. All cases were diagnosed by pathological examination without serious heart, lung and liver function damage and bleeding tendency. 1.2 Apparatus and equipment The photosensitizer was PHOTOFRIN produced by AXCAN Pharmaceuticals, Canada, and the laser machine was a 630 PDT special machine produced by DIOMED, UK. 1.3 Treatment method The dose of PHOTOFRIN was administered at 2mg/kg body weight, and the drug was diluted to 2.5mg/ml with 5% glucose injection and injected slowly by vein. Forty-eight hours after drug administration, the lesion area was irradiated with 630 nm laser. For surface irradiation of exposed lesions, microlens fiber was selected with an irradiation dose of 200J/cm2~300J/cm2; for intertissue irradiation of larger and thicker lesions, columnar fiber (diffuse end length 25-40mm) was selected with an irradiation dose of 300J/cm~360J/cm, and the spacing between adjacent irradiation points was 1.5-2cm. To prevent local edema caused by the treatment from affecting breathing, preoperative tracheotomy is performed. The treatment of liver and lung lesions was performed under ultrasound and CT guidance. Postoperative vital signs were observed, anti-infection treatment was routinely administered, and necrotic tissue was regularly removed. To prevent skin phototoxic side effects, direct sunlight exposure was avoided for one month after surgery. 1.4 Efficacy observation According to the recent efficacy criteria established by the 1984 National Hematoporphyrin-Laser Conference, complete remission (CR): the tumor disappears completely and lasts for more than 1 month; significant remission (SR): the product of the maximum diameter of the tumor and its vertical or tumor height is reduced by more than 50% and lasts for more than 1 month; minor remission (MR): the above mentioned tumor is reduced by more than 50% and lasts for more than 1 month. minor remission (MR): the product of the above-mentioned remission is less than 50% and lasts for more than 1 month; no remission (NR): the tumor does not shrink or increase. 2. Results 1.1 Efficacy: The necrotic tissues could be partially peeled off on the second day after treatment, and the necrotic tissues were still peeled off at the latest three weeks after illumination, and there was no local bleeding when the necrotic tissues were peeled off or peeled off. 2 cases of CR and 20 cases of SR were found in 36 cases, and the effective rate (CR+SR) was 66.1%. 1.2 Toxic side effects: 1.2.1 Local edema: severe edema occurred at the treatment site in all cases, and edema at the treatment site of head and neck tumor appeared as early as 1 hour after the start of photoluminescence and as late as 24 hours after photoluminescence. In the case of gastric cancer patients, local edema was seen to be serious when they were re-illuminated 48 hours after illumination. 1.2.2 Skin phototoxic side effects: 3 cases showed skin erythema 2 to 3 weeks after treatment, and the symptoms were relieved after antihistamine treatment and strict light avoidance for one week. 1.2.3 Local pain: 27 cases showed local pain at the treatment site, and most of them were completely relieved within 3 to 7 days after symptomatic treatment. 3. Discussion PDT therapy is to use a certain period of time after the body ingests photosensitizer, when the photosensitizer forms a relatively high concentration in the tumor, to irradiate the tumor with certain wavelength of light, to stimulate the oxygen molecules to produce highly oxidizing active singlet oxygen and free radicals to destroy the tumor cells, causing tumor tissue necrosis, and then achieve the purpose of tumor treatment, and the damage to the tumor trophoblastic vessels is especially obvious [1]. PDT is particularly suitable for patients who cannot tolerate surgery and radiotherapy, those whose tumor growth sites are special and difficult to perform extended tumor resection, those who remain or recur after other treatments, and those who refuse surgery because of possible disfigurement. PDT is especially suitable for patients who cannot tolerate surgery and radiotherapy, those who are difficult to perform extended tumor resection after other treatments, and those who refuse surgery because of possible disfigurement; its scope of application is wide. Currently, authorities in Europe and the United States have only approved the application of this therapy to the treatment of intraluminal tumors such as esophagus, bronchus, and bladder [2], while in China, it has been reported that the application of this therapy has been extended to solid tumors in the liver, lung (peripheral lung cancer or metastases), brain, and breast using interstitial irradiation [3]. It has been more than 100 years since the first human discovery of photochemotherapy response, yet it was not until the invention of laser technology in the 1960s that PDT could be truly used clinically. With the continuous improvement of laser and fiber optic technology, with the cooperation of today’s advanced imaging equipment, it is possible to deliver the required wavelength of light to almost any part of the body. In contrast, the development of photosensitizers has encountered many problems, mainly: (1) poor selective absorption by tumor tissues, and the relatively high concentration in the tumor is only caused by the difference in excretion rate of photosensitizers from tumor tissues and normal tissues. (2) Long retention time in vivo, and patients need to be protected from light for a long time after treatment. Although PHOTOFRIN is still not a good solution to these two major problems, it has been greatly improved over other photosensitizers used in early clinical practice. It is a photosensitizer approved by the FDA for clinical use, and its efficacy on intratumoral tumors has been reported in foreign literature [4], but there is no report on the treatment of malignant tumors by intertissue irradiation. We performed 36 cases of malignant tumors using PHOTOFRIN/DIOMED 630 PDT and achieved satisfactory results. The recent side effects mainly include edema at the treatment site, skin phototoxic side effects and local pain in individual cases. The preliminary results indicate that inter-tissue irradiation with PHOTOFRIN/DIOMED 630 PDT for the treatment of malignant tumors has precise local efficacy and mild toxic side effects, and is worth promoting.