Nature of Cancer

I was completely entranced by the April 9th, 2009 Nature Podcast. It featured Mike Stratton and the work of himself and his colleagues from the Wellcome Trust Sanger Institute, who have been doing high throughput sequencing of individual cancer cells.

There are 100 million million or 100 trillion cells in the human body. Compare that to the number of stars in the galaxy, which is 200 billion. Given that many cells and the number of mutations going on, why is it that only 1 in 3 people that develop cancer? Only a few mutations cause cancer. The types of mutated genes that you need to develop cancer would be the ones that govern biological functions that modulate cell proliferation, modulating the cell cycle, or that are involved in apotosis (cell suicide necessary to stop bad mutations from proliferating - a function that cancer has to shut down to be successful). There are also mutations in genes involved in subtle processes like cell metabolism. We don't know how many genes have to mutate to cause a cell to have cancer. It might be 5 to 20 abnormal genes. In other words, for a cell to become a cancer cell, it has to shut off cell death, turn on uncontrolled proliferation, and alter cell metabolism.

The information is in the cells and decoding is the key. There are now coming online advances in computing to track this information that will make it possible to answer these questions. If they could sequence cells from all over your body, and compare healthy cells to cancer cells, they could see what the cancer mutation is.

This is what they are working on. It's called the Cancer Genome, or the genetic code of a single cell within a cancer. If you look at one cell, you'll find a bunch of somatic mutations. If you track many cancer cells, you can track mutations going back to fertilized egg.

Figuring out which genes are active in cancer will enable us to understand information about driver mutations. We'll be able to track what mutations cause cancer to have growth advantages. We'll be able to use that knowledge to identify active cancer genes in our bodies (to find cancer outbreaks) and to craft treatments that specifically counter what is going wrong. This brings great hope in diagnosis and treatment. The speed with which these major advances in the last few years have come about means that new therapeutic solutions will not be far behind. Hopefully, there are enough researchers following this line of study finding abnormal genes and discovering what cancer weaknesses can be targeted.

Given the sources of variation in mutated genes found from studying cancer, we should also be able to look back in time and see what the host (person) was exposed to that caused the cancer. We might also be able to learn what defects in the DNA repair process may have caused the error.

We might soon craft therapies to help a specific patient. We only need to know what types of cancer genes are active in that person. We should be able to target drugs toward specific cancer traits, once we have identified them in that person. Rapid and inexpensive diagnosis will be the key, since we will need exact information from a person to pick the right drug or treatment. Within 10 years, all patients will have their cancers sequenced, that will be the common diagnostic tool, just as blood work and x-rays, CT scans, and MRIs are today.

It's a very interesting and active field.