Influence of treatment-induced changes in tissue absorption on treatment volume during interstitial photodynamic therapy

Interstitial photodynamic therapy on thick skin lesions has been shown to induce changes in tissue light transmission as a direct consequence of variations in total blood volume and oxygen saturation. A finite element method was used in order to simulate the fluence rate distribution and total light dose throughout the target tissue for two cases. The first case constitutes a pre-treatment model where the tissue optical properties are assumed constant during the entire treatment. The second situation takes into account observed changes in tissue light transmission, small deviations in fiber insertion depth and a few cases of almost complete loss of source fiber output power possibly as a result of blood accumulation in front of the fiber tip. The pre- and post-treatment models from six clinical treatments are compared in terms of simulated treatment volumes. We conclude that real-time monitoring of the delivered fluence is necessary in order to ascertain a pre-determined light dose to the target tissue. Finally, we speculate on how to also include the sensitizer fluorescence level and tissue oxygenation in the real-time treatment feedback.     

Conjugated Polymer‐Based Nanoparticles for Cancer Cell‐Targeted and Image‐Guided Photodynamic Therapy

Multifunctional materials with cell imaging and therapeutic functions are anticipated to provide promising agents in cancer treatment. Herein, folic acid modified conjugated polymer nanoparticles (FA‐CPNs) are exploited to target cancer cells and destroy the neighboring cancer cells. Folic acid in FA‐CPNs enables the strong binding with high affinity to folate receptor, a cancer‐cell‐associated protein, to target cancer cells. FA‐CPNs are able to produce cytotoxic reactive oxygen species upon irradiation 600 nm light, and therefore cause the cell death of folate receptor‐overexpressed cancer cells effectively. Therefore, the conjugated polymer‐based nanoparticles provide a multifunctional system for targeting cancer cells and photodynamic therapy.     

肿瘤患者光动力疗法光过敏反应的护理

对128例肿瘤患者行光动力治疗后，5例出现光过敏反应，经及时对症治疗和再次进行避光，7～14d后全部治愈。护理要点包括：健康教育，治疗期间在专用病房避光，在规定的时间外出散步，严格进行光过敏试验，做好出院指导等。     

金丝桃素在肿瘤治疗和诊断中的应用

金丝桃素是从金丝桃属植物中分离得到的一种天然光敏剂。金丝桃素经光激活产生过氧化物可以诱导癌细胞凋亡并抑制其生长,同时其对肿瘤组织具有特异的亲和力(可以优先积聚在肿瘤组织),这种生理活性在光学诊断中已得到广泛应用。本文对金丝桃素基于光学性质的抗肿瘤作用及在光动力学诊断中的应用进行了概述,为充分利用金丝桃素资源,进行金丝桃素衍生物的研究和开发提供依据。     

Long-term survival following endoscopic and surgical treatment of high-grade dysplasia in Barrett's esophagus

BACKGROUND & AIMS: Photodynamic therapy (PDT) for high-grade dysplasia (HGD) in Barrett's esophagus is a Food and Drug Administration-approved alternative to esophagectomy. Critical information regarding overall survival of patients followed up long-term after these therapies is lacking. Our aim was to compare the long-term survival of patients treated with PDT with patients treated with esophagectomy. METHODS: We reviewed records of patients with HGD seen at our institution between 1994 and 2004. PDT was performed 48 hours following the intravenous administration of a photosensitizer using light at 630 nm. Esophagectomy was performed by either transhiatal or transthoracic approaches by experienced surgeons. We excluded all patients with evidence of cancer on biopsy specimens. Vital status and death date information was queried using an institutionally approved Internet research and location service. Statistical analysis was performed using Kaplan-Meier curves and Cox proportional hazards ratios. RESULTS: A total of 199 patients were identified. A total of 129 patients (65%) were treated with PDT and 70 (35%) with esophagectomy. Overall mortality in the PDT group was 9% (11/129) and in the surgery group was 8.5% (6/70) over a median follow-up period of 59 +/- 2.7 months for the PDT group and 61 +/- 5.8 months for the surgery group. Overall survival was similar between the 2 groups (Wilcoxon test = 0.0924; P = .76). Treatment modality was not a significant predictor of mortality on multivariate analysis. CONCLUSIONS: Overall mortality and long-term survival in patients with HGD treated with PDT appears to be comparable to that of patients treated with esophagectomy.     

In Vitro Lethal Effect of Photodynamic Therapy on Human Pancreatic Cancer Cells and Its Major Influencing Factors

OBJECTIVE To investigate the in vitro lethal effect of photodynamic therapy (PDT) using the photosensitizer hematoporphyrin on the human pancreatic cancer cell line Panc-1, the major influencing factors and the mechanisms of treatment. METHODS Three factors-the time needed for photosensitizer and cell incubation, the photosensitizer concentration (PhoC) and the exposure dose (ExpD)-were examined with different levels of these factors. Optical density (OD) was used as a measure of CCK-8 in the experiment, and was converted to the rate of cell survival. The separate effect of each factor on the photodynamic action was studied, and the interactions were investigated. The effects of different incubation times and PhoC levels on the fluorescence intensity (FI) of the intracellular photosensitizer were determined,and the mechanisms of these factors leading to the therapeutic effects of PDT discussed.RESULTS An increase in the photosensitizer and cell incubation time, an increase of PhoC, and enhancement of the ExpD, produced a corresponding decrease in the rate of Panc-1 cell survival after PDT (P , 0.05). PDT achieved its maximum lethal effects 16 h after starting the incubation, with a PhoC of 10 mg/L and an ExpD of 20 J/cm2; at these levels a synergistic interaction between PhoC and the ExpD occurred, decreasing the cell survival rate (P , 0.05). Neither simple administration of photosensitizer without ExpD (0 J/cm2) or illumination in the absence of PhoC (0 mg/L) affected the rate of cell survival (P.0.05). With an increase of PhoC and lengthening of the incubation time, the FI of the intracellular photosensitizer accordingly increased (P.0.05), and attained its maximum value at a PhoC of 10 mg/L and 36 h after the incubation. With an increase of PhoC,the FI of the photosensitizer, hematoporphyrin, in the solution increased progressively at first and then decreased (fluorescence quenching).CONCLUSION PDT with the photosensitizer hematoporphyrin has clear lethal effects on the human pancreatic cancer cell line Panc-1,but the presence of a photosensitizer and laser irradiation by themselves do not have independent lethal effects. The three influencing factors-the time for photosensitizer and cell incubation,PhoC and ExpD-correlate positively with the PDT response,within certain limits. Beyond these limits, the PDT response does not significantly increase. The main mechanism of the PDT response lies in the effect of these factors on the level of the intracellular photosensitizer and the fluorescence quenching of the photosensitizer.A synergistic effect exists between PhoC and ExpD.     

光动力治疗尖锐湿疣疗效及病理学研究

目的探讨δ-氨基酮戊酸光动力疗法（ALA-PDT）治疗尖锐湿疣的有效性及治疗前后的病理学改变。方法选择尖锐湿疣初发患者60例,随机分为3组,分别给予光动力治疗、CO2激光治疗、两者联合治疗,记录复发情况和不良反应。光动力治疗组治疗前后行组织病理检查,比较治疗前后炎症程度。结果治疗后复发率光动力治疗组、CO2激光治疗组、联合治疗组分别为20%、55%、10%,各组比较均有统计学意义（P〈0.05）,联合治疗复发率最低、说明其效果最好,光动力治疗次之,而单纯CO2激光治疗效果欠佳;3组不良反应发生率比较有统计学意义（P〈0.05）,光动力治疗不良反应发生率最低;光动力治疗前后组织病理切片炎症细胞数量间比较有统计学意义（P〈0.05）,治疗后较治疗前炎症反应明显加重。结论δ-氨基酮戊酸光动力疗法治疗尖锐湿疣可明显降低复发率,且安全、耐受性好。