Hodgkinson Natasha, Kruger Cherie A, Abrahamse Heidi
Laser Research Centre, Faculty of Health Sciences, University of Johannesburg, Doornfontein, South Africa.
Tumour Biol. 2017 Oct;39(10):1010428317734691. doi: 10.1177/1010428317734691.
Colorectal cancer is commonly treated by tumour resection, as chemotherapy and radiation have proven to be less effective, especially if the tumour has metastasized. Resistance to therapies occurs in almost all patients with colorectal cancer, especially in those with metastatic tumours. Cancer stem cells have the ability to self-renew, and their slow rate of cycling enhances resistance to treatment and increases the likelihood of tumour recurrence. Most metastatic tumours are unable to be surgically removed, thus creating a need for treatment modalities that target cancers directly and destroy cancer stem cells. Photodynamic therapy involves a photosensitizer that when exposed to a light source of a particular wavelength becomes excited and produces a form of oxygen that kills cancer cells. Photodynamic therapy is currently being investigated as a treatment modality for colorectal cancer, and new studies are exploring enhancing photodynamic therapy efficacy with the aid of drug carriers and immune conjugates. These modifications could prove effective in targeting cancer stem cells that are thought to be resistant to photodynamic therapy. In order for photodynamic therapy to be an effective treatment in colorectal cancer, it requires treatment of both primary tumours and the metastatic secondary disease that is caused by colon cancer stem cells. This review focuses on current photodynamic therapy treatments available for colorectal cancer and highlights proposed actively targeted photosynthetic drug uptake mechanisms specifically mediated towards colon cancer stem cells, as well as identify the gaps in research which need to be investigated in order to develop a combinative targeted photodynamic therapy regime that can effectively control colorectal cancer primary and metastatic tumour growth by eliminating colon cancer stem cells.
结直肠癌通常通过肿瘤切除术进行治疗，因为化疗和放疗已被证明效果较差，尤其是当肿瘤发生转移时。几乎所有结直肠癌患者都会出现对治疗的耐药性，尤其是那些患有转移性肿瘤的患者。癌症干细胞具有自我更新的能力，其缓慢的循环速度增强了对治疗的耐药性，并增加了肿瘤复发的可能性。大多数转移性肿瘤无法通过手术切除，因此需要直接针对癌症并破坏癌症干细胞的治疗方式。光动力疗法涉及一种光敏剂，当暴露于特定波长的光源时，它会被激发并产生一种杀死癌细胞的氧形式。目前正在研究将光动力疗法作为结直肠癌的一种治疗方式，并且新的研究正在探索借助药物载体和免疫偶联物来提高光动力疗法的疗效。这些改进可能被证明对靶向被认为对光动力疗法耐药的癌症干细胞有效。为了使光动力疗法成为结直肠癌的有效治疗方法，它需要同时治疗原发性肿瘤和由结肠癌干细胞引起的转移性继发性疾病。本综述重点介绍了目前可用于结直肠癌的光动力疗法治疗方法，强调了针对结肠癌干细胞提出的主动靶向光合药物摄取机制，并确定了研究中的空白，这些空白需要进行研究，以便开发一种联合靶向光动力疗法方案，通过消除结肠癌干细胞来有效控制结直肠癌原发性和转移性肿瘤的生长。
