Targeted Photodynamic Therapy as Potential Treatment Modality for the Eradication of Colon Cancer

Abstract

Photodynamic therapy (PDT) can be used to treat colorectal cancer (CRC). When a photosensitizer (PS) drug is administered to a patient, it can either passively or actively accumulate within a tumor site and once exposed to a specific wavelength of light, it is excited to produce reactive oxygen species (ROS), resulting in tumor destruction. However, the efficacy of ROS generation for tumor damage is highly dependent on the uptake of the PS in tumor cells. Thus, PS targeted uptake and delivery in CRC tumor cells is a crucial factor in PDT cancer drug absorption studies. Generally, within non-targeted drug delivery mechanisms, only minor amounts of PS passively accumulate in tumor sites and the remainder distributes into healthy tissues, causing unwanted side effects. To improve the efficacy of PDT research is currently focused on the development of specific receptor based photosynthetic nanocarrier platform drugs, which promote the active uptake and absorption of PS drugs in CRC tumor sites only, avoiding unwanted side effects, as well as treatment enhancement. This chapter will focus on current actively targeted PS nanoparticle drug delivery systems, which have been investigated for the PDT treatment of CRC cancer.

Photodynamic diagnosis and photodynamic therapy of colorectal cancer in vitro and in vivo

“…The colon and rectum intestinal wall comprise of many layers made of different tissues that serve several key functions in the gastrointestinal tract. 2,10 CRC arises from benign adenomatous polyps in the colon. 1,2 When polyps become cancerous, they become full-blown tumors on the wall of the colon and later protrude outwards into the intestinal lumen.…”

“…2,10 CRC arises from benign adenomatous polyps in the colon. 1,2 When polyps become cancerous, they become full-blown tumors on the wall of the colon and later protrude outwards into the intestinal lumen. 11,12 These outward protruding tumors can then also spread further into the cardiovascular or lymphatic system, as well as to other tissues or organs of the body, resulting in secondary cancer metastasis.…”

“…11,22 The effectiveness of these treatment modalities is highly dependent on the stages, tumor size and advancement of cancer. 2,23 Furthermore, these treatments can be used in conjunction with other treatment modalities based on the stage at which the patient was diagnosed. 2 However, reports indicate that even though these treatment modalities are developed to circumvent CRC, they still yield harmful effects post-treatment.…”

“…6 Moreover, other side effects such as bowel dysfunction, nausea, bladder dysfunction, fatigue and skin irritations have been reported from CRC patients receiving such treatments. 2…”

“…Colorectal cancer (CRC) frequently emerges from precancerous polyps that are initially conned in the innermost mucosal layers of the colon. 1,2 This devastating disease is recognized amongst the most prevalent malignancies and can be considered as the second leading cause of tumor-associated deaths in women and the third most common in men worldwide. 3 Recent projections have indicated that by 2030, the incidence and mortality rate of CRC will increase by 60% globally.…”