Tumor Mutations
Genome sequencing has revealed a large amount about human cancers.
In this blog post, I will focus on what it revealed about tumors.
Genome sequencing has allowed us to learn more about mutations in tumors and cancer.
For example, lung tumors and melanomas contain 200 non-synonymous mutations per tumor.
Non-synonymous mutations are mutations that alter the encoded amino acid sequence of a protein.
Many mutations fall under non-synonymous mutations, like nonsense and missense mutations.
One thing that we do know about tumors is that age does affect tumor mutations.
Pedicatic tumors, on average, have a 9.6 mutation rate per tumor.
When it comes to adults, these numbers get much larger.
To name a few, there are 135 gene mutations in malomana, 35 in glioblastoma, and 57 in esophageal adenocarcinoma.
This is quite a distinct difference from pediatric tumors.
So why do adults have such larger gene mutations?
https://www.facingourrisk.org/uploads/cell-damage-and-cancer2.JPG
Adults have larger gene mutations because of age.
As an example of this, I will use colorectal tumors.
One mutation that occurs is the gatekeeping mutation.
Gatekeeping mutation provides a selective growth advantage in a normal epithelial cell, which then outgrows the other surrounding cells.
This allows it to become a mircospectic clone.
In colorectal tumors, this mutation often occurs in the gene APC (Adenomatous Polyposis Coli).
This slowly grows a small adenoma (a benign tumor made of epithelial cells), which triggers a second mutation in a second gene.
This second gene releases more clonal growth, which allows an expansion of cell number.
This process of mutation just continues with other genes, like PIK3CA, SMAD4, and TP53.
This process is slow, but eventually it forms a malignant tumor.
This effect selective growth advantage (difference between death and birth in cell population), and is labeled as a driver mutation.
In a healthy adult, the selective growth advantage should have a difference of 0.
Driver mutations increase the selective growth advantage by only 0.4%.
Which you wouldn’t think is a lot, until it keeps adding up over several years.
Using the colorectal tumors explant, first then was a mutation in the APC gene, then a second gene, then in genes like PIK3CA, SMAD4, and TP53.
So, how does genome sequencing play a role in this information?
https://c8.alamy.com/comp/2F4KF5X/genome-sequencing-infographic-human-genome-project-flat-style-vector-illustration-2F4KF5X.jpg
Gemone sequencing allows us to see these gene mutations and know exactly what they are doing.
This technology has given us the ability to not just look at tumor sequences, but also compare them to normal sequences.
Letting us know what exactly what mutations are unique to tumors.
I believe that knowing how tumors form is how we create better treatments.
Wikipedia contributors. “Cancer genome sequencing.” Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 31 Oct. 2025. Web. 9 Nov. 2025
Vogelstein, Bert, et al. “Cancer Genome Landscapes.” Science, 2013, https://doi.org/1235122. Accessed 9 Nov. 2025