Cancer Therapies

Prostate cancer: using fluorescents to target disease

Prostate cancer is the most common type of cancer in males, and second highest cause of cancer deaths. Patients with low-risk prostate cancer can survive for a long time, but advanced stages of prostate cancer are associated with rapid deterioration, risk for recurrence, and metastasis to distant organs. These cancers carry a poor prognosis and often result in death. Therefore it is vital to identify even small cancers before they become aggressive so as to treat them early and appropriately. Current imaging technologies are not sensitive enough to detect small tumors or early spread.

Dyes, which are luminescent nanoparticles, have been used as contrast agents in imaging studies. Conventional dyes do not display powerful imaging to confirm the site of abnormal tissues. Further, these dyes may also be harmful to the human body. In contrast, fluorescent cyanine dyes have been successfully used as contrast agents in imaging. Indocyanine green has been safely used in ophthalmology imaging for years. Recent research has indicated that near-infrared fluorescence (NIRF) imaging is an attractive novel method in the detection of prostate cancer. In this method, special cyanine dyes are used as ideal NIRF probes which can detect prostate cancer and its spread. The nature of the dyes is such that they are taken up and accumulate only in tumor tissues and are recognized by producing strong NIRF signals while normal tissues are left unaltered. It has been established that near infrared light radiation has the ability to penetrate up to 10 cm deep in certain tissues. On imaging, the dyes exhibit superior optical characteristics and rapidly detect and diagnose prostate cancer in real-time. The dyes are compatible with human tissues and produce little or any side-effects. This imaging technique involves NIRF probes with an emission wavelength in the near-infrared region; similar to the contrast agents that have been used widely in positron emission tomography (PET scans).

NIRF dye-mediated imaging has been validated in different experimental settings, in vivo and in vitro prostate cancer studies. This method has proven to be reliable as a non-invasive method not only for the diagnosis providing details of the tumor, but also in the assessment of tumor progression and guiding therapy. However, for specific anatomical details concurrent imaging modalities such as MRI, CT, and PET may be utilized. Additionally, the dye can be injected prior to surgery and the affected lymph nodes are lit up, sparing normal lymph nodes. This is of great assistance to the surgeon to not only tackle the tumor, but also the affected nodes. This type of intraoperative use of the fluorescent dye has taken the use of fluorescent dyes in prostate cancer to the next level.

In conclusion, fluorescent dyes are invaluable in the management of prostate cancer. NIRF dye-mediated imaging is a feasible and practicable method for prostate cancer detection, and further research may offer an insight for this method to be routinely used in clinical settings. This type of cell imaging by using fluorescent dyes for prostate cancer diagnosis is simple, cost-effective, and utilizes relatively sensitive techniques.