Team:Thrace/Description
What is the problem?
Colorectal cancer is a form of malignancy that occurs in the colon or rectum. It is the third most common form of cancer in the world and the second most lethal. Colorectal cancer constitutes a predominantly modern form of cancer, as it is often correlated to the modern lifestyle. A diet poor in fiber and rich in red and processed meats, alcohol consumption and smoking are a few of the risk factors that contribute to the high incidence rate of colorectal cancer.
Colorectal cancer cases through the years
5-year survival rate depending on the stage of disease
When colorectal cancer is diagnosed early, at the localized stage, the 5-year survival rate reaches 91% for colon cancer and 89% for rectal cancer. On the contrary, the 5-year survival rate significantly plummets at later stages (14% for colon cancer and 16% for rectal cancer). Hence, early detection is key for the successful treatment of this form of cancer.
The two most used methods in screening for colorectal cancer are colonoscopy and stool tests. In Greece, it is advised that people over 50 (or younger, depending on their medical history) have a colonoscopy performed once every five years and a stool test once every two years. These two diagnostic tools can screen for colorectal cancer with substantial accuracy.
Screening for colorectal cancer has long been incorporated into the list of necessary screening procedures. This fact, combined with the remarkable 5-year survival rate that accompanies early detection, could lead one to assume that the mortality rate of colorectal cancer should be low, since people can be diagnosed early. Nevertheless, this isn’t the case, as proven by the high ranking of colorectal cancer in the list of different cancer forms’ fatality. In fact, just over 60 % of adults over 50 follow the recommended screening regimen in the US
Mortality of colorectal cancer through the years in the USA
Reading about this problem incited us to look into why so many people avoid getting screened. The main reason for non-compliance with the recommended regimen of colonoscopy is the discomfort of the examination. Stool tests do improve compliance of patients, but they are still no panacea. A percentage of the population finds these tests uncomfortable too. What is more, even though these tests exist in many countries (one of them being Greece), they aren’t used very often. These facts led us to form the conclusion that a less invasive and more comfortable screening method would attract more people to get screened for colorectal cancer.
This is where our project SaliCa enters the picture. SaliCa is a device that can detect colorectal cancer in a person’s saliva. It targets two biomarkers that have been associated with colorectal cancer, a gene from Fusobacterium nucleatum and micro RNA 766-5p. The device detects the two biomarkers and quantifies them. In case the biomarkers are present in alarming amounts, the device will produce a positive result and motivate the test taker to visit their doctor for further examinations.
How it works
SaliCa combines RPA and CRISPR (as in SHERLOCK) to detect and quantify specific biomarkers which have been associated with colorectal cancer. First, using recombinase polymerase amplification (RPA) it amplifies the biomarkers. Then CRISPR follows. With the employment of Cas12a, guide RNAs and RNA with fluorescein and biotin, the biomarkers are detected and quantified. Cas12a binds to the sequence of the biomarker with help from the guide RNAs. That’s when the cleavage activity of the enzyme is activated, leading to it cleaving the fluorophore RNA. Therefore, fluorescence is emitted and quantified,producing a positive result.
Characteristics of SaliCa
Quick: the result is available in 1 hour
Pain-free: requiring just a saliva sample, the device provides a screening method that doesn’t involve any pain or discomfort.
At-home use: the test can be performed by the test-taker themselves, from the comfort of their own home, without having to visit medical facilities.
Inexpensive: the device will be available for purchase in any pharmacy for a low price
Eco-friendliness: SaliCa doesn’t require any batteries to work, as it uses light as a source of energy. Furthermore, it can be used multiple times, just by changing the recyclable cartridges.
With our device we hope to show to the general public that medical examinations can be done quickly and without any pain. In this way, we wish to encourage people to take action on their health and help to move medicine towards a less invasive and more sustainable future.
References
- https://www.wcrf.org/dietandcancer/colorectal-cancer-statistics/
- https://www.who.int/news-room/fact-sheets/detail/cancer
- https://www.cancer.org/cancer/colon-rectal-cancer/causes-risks-prevention/risk-factors.html
- https://www.cancer.org/cancer/colon-rectal-cancer/detection-diagnosis-staging/survival-rates.html
- https://www.cancer.org/content/dam/cancer-org/research/cancer-facts-and-statistics/colorectal-cancer-facts-and-figures/colorectal-cancer-facts-and-figures-2020-2022.pdf
- Voiosu, A., Tanţău, A., Garbulet, C., Tanţău, M., Mateescu, B., Băicuş, C., Voiosu, R., & Voiosu, T. (2014). Factors affecting colonoscopy comfort and compliance: a questionnaire based multicenter study. Romanian journal of internal medicine = Revue roumaine de medecine interne, 52(3), 151–157.
- Prince, M., Lester, L., Chiniwala, R., & Berger, B. (2017). Multitarget stool DNA tests increases colorectal cancer screening among previously noncompliant Medicare patients. World journal of gastroenterology, 23(3), 464–471. https://doi.org/10.3748/wjg.v23.i3.464
- Vlachonikolou, G., Gkolfakis, P., Sioulas, A. D., Papanikolaou, I. S., Melissaratou, A., Moustafa, G. A., Xanthopoulou, E., Tsilimidos, G., Tsironi, I., Filippidis, P., Malli, C., Dimitriadis, G. D., & Triantafyllou, K. (2016). Academic hospital staff compliance with a fecal immunochemical test-based colorectal cancer screening program. World journal of gastrointestinal oncology, 8(8), 629–634. https://doi.org/10.4251/wjgo.v8.i8.629
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