Cancer is a word that most of society fears. The reason being that cancer is extremely smart and innovative, but this means that in order to beat cancer, we have to be just as innovative and smart if not more so. Nanoparticles are the answer. Anyone that has had cancer or knows someone who has had it, know that surgically resecting the whole tumour is the mainstay treatment for solid tumours, and it is the most preferred because it is the most effective.
However, the problem is that during surgery it can be very difficult for doctors to determine the difference between health and malignant tissue, especially when on a miniscule scale. This limitation is challenged only by visual and tactile cue, as well as the experience that the surgeon has.
Unfortunately, the ultimate cause of death for a patient with cancer tends to be the cancers pathogen spreading and not from the primary tumour. Therefore, removal of the whole tumour and any extra fragments is vital to patients decreased chance of reoccurrence and increased survival.
Positive surgical margins (PSM) are associated with excess pathogens that were not removed from surgery and occur in about 14-36% of surgeries that resected the tumour.
To aide in the complete removal of cancer and decrease PSM rates, surgical tumour imaging techniques have emerged. Specifically, the use of nanotechnology as they have the ability to be directed to tumours and can provide imaging feedback to surgeons during treatment. Likewise, the advances in engineering and optics have allowed this research to take place, as nanoparticles and image-guided surgery rely heavily on these developments. Such imaging advancements are the optical strategies used for image-guided surgery.
X-rays, ultrasounds, MRIs, etc. are all great imaging devices for diagnosis, staging and preoperative planning, however, they limit translation into the operating room. Image guided surgery is guided with real-time optical imaging feedback. This allows for the surgeon to properly and effectively locate the tumour, detect the residual disease and identify any cancerous or pathogenic fragments in surrounding areas, all while preserving the healthy tissue. This is completed by injecting the patient before surgery with an exogenous contrast agent that accumulates in the tumour and clears the healthy tissue, allowing a contrast to be seen by the naked eye.
The surgeon can then use an imaging system that is specific for the agent that was injected and remove the cancer using real-time image guidance. Most importantly, the doctors can identify any remaining cancer and remove that, which lessons the patients chance of reoccurrence.
One strategy for image guided surgery is using fluorescence, which is the most utilized for tumour detection as it has many advantages. Fluorescence uses particles that glow when observes, and they have high tissue penetration.
Another benefit of fluorescence is that absence of ionizing radiation and high spatial resolution, which in terms of humans means less risk to tissues and a greater visibility for surgeons while operating. Another strategy is photoacoustic imaging, which uses a combination of ultrasounds and light to provide 2D and 3D images or organs and tissues. To isolate the tumour for surgeons, the light laser is directed toward the general area of the cancer, where the energy is absorbed by the tumour and converted to heat, where an ultrasound can detect the area and provide doctors the exact whereabouts of the main tumour and any other cancerous fragments. Additionally, a surface-enhancing resonance Raman scattering technique relies on light interactions to find the tissue of interest. Each tissue has a specific coding, otherwise known as a Raman fingerprint, that can be detected given the proper light interactions, which is what this method utilizes to be successful.
Lastly, multimodal imaging uses a combination of imaging modalities considering each one listed above have flaws, as they are only single systems. Using multiple techniques allows for different combinations for any desired preference that a doctor might have. Several nanoparticles and dyes are used in imaging modalities to provide a proper contrast to the naked eye, however there are many issues. There still needs to be research and trials done to better improve tumour specificity, faster tumour uptake and longer retention. To be successful in this field and find the precise nanoparticles and imaging strategy for each certain cancer, these critical issues need to be addressed
to rule out under-performances before surgeons start using the technique.
While there are several challenges in this research, the use of nanoparticles with image-guided surgery is very exciting. This will be the innovative and effective approach to outsmart the smartest thus far; cancer.
Wojtynek, N., & Mohs, A. (2020). Image‐guided tumor surgery: The emerging role of nanotechnology. Wires Nanomedicine And Nanobiotechnology. doi: 10.1002/wnan.1624