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Laser Technology in Cancer Treatment
- Nov 07, 2018 -

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Cancer can someday be overcome. On this road, laser technology has been highly anticipated and has made some progress in recent years.

In the current mainstream cancer treatment methods, chemotherapy, radiotherapy, and surgery are not only expensive, but also cause deterioration of immune system function, and are not suitable for cancer patients. Therefore, more treatments will gradually be developed. At present, laser technology mainly includes three aspects in cancer treatment: imaging diagnosis, adjuvant therapy, and direct therapy. The OFweek laser network will review the progress of laser technology in cancer research from these three aspects.


Imaging Diagnosis

The imaging diagnosis of laser on cancer can accurately lock cancer cells and provide an effective reference for subsequent treatment options.

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Quantum cascade lasers reduce analysis time

Infrared imaging is a reliable method of organizing cells. The currently used method is the Fourier Transform Infrared Spectroscopy (FTIR) microscopy technique, but the time required for this technique analysis is too long, hindering the use of infrared imaging in the clinical environment.

In May of this year, a research team from Ruhr University (RUB) in Bochum, Germany, deployed an infrared microscope with a quantum cascade laser (QCL) to replace FT technology with QCL technology. By using QCL to simplify measurement setup, the team reduced the time required for analysis from one day to a few minutes. Coupled with bioinformatic image analysis, QCL-based infrared microscopy can perform label-free cancer tissue classification and can be fully automated.


Compared to FTIR microscopes, QCL-based infrared microscopes allow the use of a single frequency. Therefore, an overview image of the target area can be obtained in a very short measurement time, which can then be analyzed in detail. The team used QCL-based infrared imaging to analyze 110 cell tissue samples taken from colorectal cancer patients. The results of this unlabeled method showed 96% sensitivity and 100% specificity compared to histopathology, which is considered the gold standard in routine clinical diagnosis.


Terahertz spectrum: new progress in cancer diagnosis and treatment

Terahertz (THz) is located between the microwave and infrared regions of the electromagnetic spectrum, with a frequency range of 0.3 to 3x1012 Hz, providing a unique perspective for the internal access of biological cells and provides a non-ionizing method of cancer imaging. With the introduction of laboratory terahertz sources and sensitive detectors, terahertz technology will have a major impact on clinical applications.

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The "Towards the THz Imaging of Cancer" conference, held in August this year, brought together researchers, clinicians and industry insiders to explore how to turn terahertz imaging into an effective clinical tool.


At the conference, Norbert Klein of Imperial College London said that the measurements in the terahertz and microwave bands are sensitive to the water content of the cells and can be quickly obtained without labeling. Emma Pickwell-MacPherson of Warwick University is working on terahertz imaging in vivo. She said that terahertz imaging can be used to detect differences in tissue water content between diabetics and controls. Imaging monitoring of fine tissue changes in scar healing can also be performed. In addition, terahertz technology can detect differences between normal and cancerous tissues. However, in vivo detection is challenging due to the need to control a large number of variables.

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▲Professor Peter Weightman of the University of Liverpool

In the panel discussion, speakers explored the future potential of terahertz imaging. They believe that in order to apply terahertz technology to the healthcare industry, it is necessary to compete with existing technologies on practical issues, such as cancer management. Anything that can detect early diseases is very important. It may also be a rapid assessment of lymph nodes during surgery. Perhaps terahertz can even treat cancer, selectively heat the light and destroy cancer cells. Peter Weightman, a professor of physics at the University of Liverpool, points out that it is not difficult to distinguish between cancer and non-cancer. Histology can do this. What is more challenging is to determine if the tissue will develop cancer and whether the lesion will worsen.


Adjuvant therapy

Adjuvant therapy refers to laser technology as a means of assistance, combined with other drugs or medical technology to treat cancer cells, such as laser minimally invasive, photodynamic therapy.


Laser minimally invasive technique

In May of this year, the research team at Purdue University in the United States developed a minimally invasive technique that would help doctors better detect and treat cancer cells, tissues and tumors without affecting nearby healthy cells. This method, known as PLASMA, combines cold atmospheric pressure plasma (CAP) with electroporation and/or photoperiod to destroy cancer cells without damaging nearby healthy cells.

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CAP is an almost room temperature ionized gas that introduces reactive oxygen or nitrogen into cancer cells, tissues or tumors. The cell membrane is then cut using an electric field or laser to facilitate entry of the above reactive oxygen or nitrogen species. Once the amount of active substance reaches a critical level, it causes apoptosis (death) in cancer cells. Healthy cells in the vicinity are either unaffected or have minimal impact and are easily restored to normal levels. This method has been shown to be effective in several types of cancer cells and cancer cell lines in the laboratory, including breast cancer, oral cancer/cervical cancer, and prostate cancer.


Prasoon Diwakar, one of the PLASMAT developers, said: "Compared to other treatments, the combination of these three techniques has improved the effectiveness of cancer cells by 70% to 90%." In addition, PLASMA is not in the process of treatment. Chemicals are introduced into the body and are less expensive than chemotherapy or radiation therapy. This technology is more mobile than traditional cancer treatments because the required equipment size is small and readily available in most medical settings.


Photodynamic therapy

Photodynamic Therapy (PDT) is a new method for the treatment of tumor diseases with photosensitizing drugs and laser activation. It is a photochemical reaction accompanied by biological effects involving aerobic molecules. Compared with traditional tumor therapy, PDT has the advantage of being able to perform precise and effective treatment without trauma and with few side effects.

In August of this year, a group of researchers at the Korea Institute of Science and Technology developed a near-infrared photodynamic therapy that effectively compensated for the shortcomings of current PDT technology. They developed a photosensitizer called Mitochon-targeted Photodynamic Therapy (MitDt) that maximizes the PDT effect while reducing unwanted side effects. Because mitochondria play an important role in metabolism and have a high transmembrane potential, mitochondria are used as a target to maximize the action of photosensitizers.


According to the research team's research, when the mitochondria are irradiated by laser, reactive oxygen species (ROS) are produced and the mitochondrial membrane potential is immediately lost, which in turn triggers apoptosis. Therefore, the combination of PDT reagent and mitochondrial targeting agent can cause rapid damage of tumor cells, improve the therapeutic effect, and reduce unnecessary side effects. In order to apply mitochondria-targeted photosensitizers, the team developed a near-infrared PDT reagent that can be used to treat deep-tissue malignancies due to the permeability of near-infrared lasers. It also reduces light scattering and achieves a higher therapeutic effect.


However, singlet oxygen produced by normal cells when irradiated with near-infrared lasers is also a tricky problem. To solve this problem, the team developed a new photosensitizer that combines a functionalized near-infrared dye and a mitochondrial targeting agent to quickly clear the organelles after treatment and persist in cancer mitochondria for a long time to increase The amount of active oxygen that the laser illuminates at the target site. To validate the treatment, the team injected MitDt into tumor-bearing mice. They were irradiated with a near-infrared laser with a wavelength of 762 nm to induce cancer treatment, which eventually reduced the tumor area by a factor of three.


Direct treatment

Direct treatment actually refers to the use of laser precision to replace standard surgical tools (scalpels).

This method is to vaporize by irradiating a high-energy laser beam onto the tissue to raise the temperature of the tissue.

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Cancer tumors located on the surface of the human body can be directly vaporized by laser heating. For a relatively large tumor, or a large tumor that grows inside the human body, the energy of the laser beam must be used to heat the blood vessels surrounding it, so that the cancer tissue and surrounding tissues are "broken off" to reduce the spread of cancer cells. The opportunity to metastasize and then laser ablate the cancerous tissue. At present, CO2 laser and argon laser can be used to remove surface cancer, and Nd:YAG laser can be combined with endoscope to treat cancerous changes of internal organs such as uterus, esophagus and colon.


Lasers are more accurate than standard surgical tools and have less damage to normal tissue, thus causing less pain, bleeding, swelling, and scarring to the patient.




Sum Up


Despite the many advances in laser technology, there are only a few successful cases in the clinic that have not been widely promoted. In the future research path for cancer, laser technology is expected to achieve greater breakthroughs and applications. In the face of the current public enemy of cancer, it is still only prevention-oriented, everyone must maintain healthy living habits.


(This article was transferred from: OFweek )