Cancer: An Early Start to Combatting this Disease

Cancer is when abnormal cells grow out of control through mitosis and crowd the normal cells, therefore hindering the body’s ability to function properly. Normally, doctors and researchers are able to tell if someone has cancer through observing a process called methylation. Methylation happens in every organism. In a mammalian cell, a methyl group attaches to the 5’ end of cytosine residues in CG dinucleotides. These CG nucleotides are not randomly placed through the gene sequence, instead they are usually clumped together in places called CpG islands that are mainly present in specific gene promoters. Methylation of CpG islands typically causes gene silencing, with demethylation of those sites causing transcription. Methylation physically prevents the binding of regulatory proteins that promote transcription. This happens through the binding of methylation-sensitive proteins that hide regulatory sequences and interact with histone modifications which modulate the structure of chromatin. This changes the accessibility of transcriptional machinery to the promoters, which explains how methylation prevents transcription. All these processes work together and compress nucleosomes into an unfavorable formation called heterochromatin; a formation that is not ideal for transcription. The methylation process within malignancies is currently being observed in breast, pancreatic, and gastric cancer. The changes in methylation within tumour cells are creating diagnostic tests for biomarkers and potential targets for curing the source of cancer. Methods previously used to monitor the methylation process are Methylation Specific PCR, SMART-MSP (a curve analysis method), and MethyLight (a laser based test). There were many drawbacks to these methods, such as a higher chance of false positives if the primer design wasn’t accurate, or that it failed to work for heterogenous methylation. These processes all consisted of scientists collecting blood samples from patients who already had cancer [1].

A Method Which Detects Cancer 4 Years Before Symptoms Appear

Kun Zhang, a bioengineer from the University of California, helped with this research, and said that the test they created was able to detect signatures in the test subjects’ blood that showed that they had cancer four years before even stepping into the hospital! The mindset that this research group had was, “The best you can prove is whether your method is as good at detecting cancer as existing methods.” Zhang says, “You can never prove it’s better.” [2]

This process started out with the collection of blood samples from 123,000 healthy individuals in 2007. Over 1.6 million blood samples were collected. From these samples there were around 1,000 participants who eventually developed cancer. The team focused on creating tests for 5 of the common cancers: stomach, oesophagus, colorectal, lung, and liver cancer. They developed a test called ‘PanSeer’ which detects the methylation patterns when a chemical group is added to DNA to alter the genetic activity. Abnormal methylation is what signals different types of cancer. The test works by observing the methylation process in 500 different locations along the DNA sequence from the different blood samples. These locations are known as biomarkers and they have the greatest chance of signalling cancer. The team then used a machine learning program that detects the chances of the person having cancer. This test was able to detect cancer up to four years before symptoms showed with 90% accuracy and 5% false-positive rates. Zhang’s next goal is to use the test to diagnose pancreatic cancer [2].

Applications

This discovery relates to Sustainable Development Goal 3: Good Health and Well-Being. Evidently, being able to detect cancer early will help many people avoid the costly treatment plans to cure it and save them a lot of pain both mentally and physically. This test will help people plan out a better future for themselves by getting into the right eating and exercising habits as early as possible. Methylation observation tests will also be useful in a lot of countries that are not as economically advanced and have smaller high-risk populations as they will save them plenty of money and lives.

It is important to note that this method still has limitations as many scientists warn that although five different cancers can be tested, there are still many that cannot be detected. Therefore, if one test says that one will not have any of the detectable cancers, there is still a chance that they can be affected by another type of cancer.

Overall, this approach not only helps people, but also makes significant advances in the scientific field as far as blood plasma experiments are concerned, promising to eventually help find cures to other diseases or diagnose them well before symptoms show [2].

References

[1] R. Nuwer, (2020, July 21). “Experimental Blood Test Detects Cancer Up to Four Years before Symptoms Appear,” Scientific American, [Online]. Available: https://www.scientificamerican.com/article/experimental-blood-test-detects-cancer-up-to-four-years-before-symptoms-appear/

[2] A.V. Paska & P.Hudler, (2015, Jun. 5). “Aberrant methylation patterns in cancer: a clinical view,” NCBI, [Online]. Available: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4470106/