Brachytherapy combined with photobiomodulation for prevention of radionecrosis during cancer therapy

Abstract

Malignant cancer incidence has increased significantly in recent years due to continuous population growth and aging. The cancer treatment usually consists of individual or combined use of chemotherapy, surgery and radiotherapy depending on the etiology of the tumor. Following radiotherapy (brachytherapy or teletherapy), some severe complications can affect exposed healthy tissues due to unspecific molecular damage caused by ionizing radiation leading to diverse manifestations from erythema to radionecrosis. These complications are most marked in tissues containing cells with intense metabolic and proliferation activity, such as mucosae and skin tissues. Current investigations for cutaneous radionecrosis may provide therapies which revitalize affected tissue and impair the progress of skin deterioration. A promising alternative to treat radionecrosis relies on light-based therapeutic platforms such as photobiomodulation (PBM, formerly known as low-level light therapy or LLLT), However, as it might be deduced, such cell stimulatory effects could present a risk factor on tumors since, in theory, it could lead to increased tumor aggressiveness; although our group has recently reported that tumor cells don't undergo increased proliferation rates as seen in non-tumor cells after in vitro irradiation. Therefore, it is noteworthy to investigate any harmful effects that could potentially emerge from PBM treatments of peritumoral ulcers of experimental animals. We intend to investigate the effect of PBM delivering laser irradiation directly on invasive (LNCaP) and non-invasive (PC-3) mice tumors with or without the iodine-125 seed to compare and complement our preliminary results made in tumor-free mice. In this study, we will treat experimental prostate tumors (LNCaP and PC-3) with 1,16 mCi iodine-125 seeds and use PBM to evaluate tumor and avoid the radionecrosis responses to light-therapy. (AU)