New Diagnostics Methods for Colorectal Cancer Early-Detection

Colorectal Cancer (CRC) is currently one of the main public health challenges in Western countries. In many countries, it is the most prevalent cancer, and it is estimated that 2 million new cases have arisen worldwide in 2020 [1]. CRC has a relatively low 5-year survival rate of 50%, even though, if it is diagnosed in its earliest stages, survival increases to 95% [2]. The problem is that survival is only 8% if the diagnosis is made in the late stages of cancer. Given these data, we should ask why such a high number of CRC are diagnosed in their later stages. In most advanced countries, the population has access to annual or biannual screening campaigns. This screening system is based on Faecal Immunochemical Test (FIT) in many countries and tries to identify traces of blood in the stool. If a patient has a positive FIT test, a colonoscopy is recommended because the chances of having polyps (the precancerous lesion) or CRC is increased. Colonoscopy is the standard diagnostic method for two reasons. The first is that is the only imaging technique able to remove polyps in the same endoscopic intervention, causing less discomfort to the patient. The second is that, if a cancer is diagnosed, biopsies are obtained to confirm it and a surgical operation is prescribed to ensure the complete removal of the malignant cells. However, colonoscopy is not perfect and may miss some lesions and requires preparation that is very uncomfortable for patients. In recent times, a significant number of technologies have appeared for the early detection of CRC, the liquid biopsy standing out among all of them. Liquid biopsy allows, through a simple blood draw, to know if a patient has CRC, even in its most preliminary stages [3]. However, the liquid biopsy does not replace colonoscopy since, if CRC is suspected, what is recommended in clinical practice is to proceed with a colonoscopic examination.

But why is colonoscopy not a 100% reliable method? Experts estimate that, on average, 22% of polyps are missed at colonoscopy [4]. The reasons are multiple, for example, the colonoscope camera has a very limited range of vision −180°−, some polyps can “hide” behind the multiple folds of the colon or be “overshadowed” by remains of faeces if the patient is not well prepared or even if the endoscopist does not identify them [5]. In fact, there are several studies that correlate the endoscopist’s hours of experience with their Adenoma Detection Rate (ADR) that is the most important parameter related with CRC prevention [6]. Other studies have reported how this ADR can vary for the same endoscopist as the day progresses and he accumulates more fatigue. Because of all these factors, today, 8% of colorectal CRC are interval cancers, that is, cancers that are diagnosed after a negative colonoscopy [7]. To improve colonoscopy, a battery of very diverse technologies has been developed in recent years with the aim of visualize more colonic mucosa. These new tools range from mechanical devices that help flatten the colonic mucosa to prevent polyps from being hidden, to artificial intelligence systems that automatically trigger a signal to alert the endoscopist [8]. However, all these technologies only can diagnose what is seen in the screen. A very innovative approach is microwave vision technology, known as microwave imaging. Through the emission and reception of microwaves, as if it were a radar, the dielectric properties of materials can be known, such as conductivity and permittivity [9]. Our group has been working on this system during the last 5 years and has confirm the initial hypothesis that if there is a lesion with abnormal growth in the mucosa, there will be a difference between the dielectric properties of the lesion and the healthy mucosa that can be detected by microwaves. Once the initial hypothesis had been validated, a device consisting of a set of miniaturized antennas was built as an accessory device to be mounted at the tip of the colonoscope. Up to know, it has been tested in preclinical studies using phantoms and ex-vivo tissue showing very promising results [10,11]. Soon this technical innovation will be tested on patients.

The authors of this article, in addition to their academic affiliations, are part of the university spin off MiWEndo Solutions, S.L.. This work was supported by the Spanish Ministerio de Economía, Industria y Competitividad, DTS 17/00090 and CERCA Programme/Generalitat de Catalunya. Glòria Fernández Esparrach had a personal grant from Instituto de Salud Carlos III (PI17/00894). Alejandra Garrido acknowledges the financial support from DIN2019-010857/AEI/10.13039/501100011033. Roberto Sont, Marta Guardiola, and Ignasi Belda acknowledge the financial support from the European Union’s Horizon 2020 research and innovation programme under grant agreement no. 960251.

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