Each year in the United States we lose close to 600,000 people from cancer (source:American Cancer Society). This is almost the same number of deaths as there have been in all US war combat-related deaths combined (~850,000; source Wikipedia). Take a look at the graph below by the American Cancer Society showing cancer death rates for a variety of different cancers and you will notice that in several cases significant progress has been made. Nevertheless, there is still much more that needs to be done and I think there is hope. Here is why.
Let’s first go back to the 1990s. Pearl Jam was on the radio, the internet was young, and the US government was investing a few billion dollars to sequence the DNA of a human, an endeavor known as the Human Genome Project (the genome is defined as all the DNA in an organism). DNA is found primarily inside the nucleus of a cell and it is the instruction book that the cell follows to work properly. Unlike the 26 letters in our alphabet, DNA only has a 4 letter code. This code however, creates the beautiful diversity and fascinating complexity we see on our planet. In fact, we share this same code with all living organisms from trees to mosquitoes to our pets at home.
After more than a decade of sweat, science, and sequencing, the Human Genome Project announced that it was done and handed us the first human DNA sequence that was about 3 billion letters long. There was lots of hype around this and big promises were initially made about this revolutionary achievement, but it remained hotly debated as to whether it was a success. Sure, we sequenced the genome but what have learned? What do we do with this code to help humanity?
Before we answer this, let’s get back to the present. Instead of costing $3 billion and taking a decade to sequence all the DNA in a human cell, we can now sequence a human genome in about 1-2 weeks at about $3000. This is extraordinary scientific progress! The development of the new enabling sequencing technology is like comparing our computer desktops in the 90s to our sleek and powerful phones we have today. The Human Genome Project helped stimulate this amazing new DNA sequencing technology but this is just the beginning. In fact, this technology and knowledge will create hope for our cancer patients.
In the next 2-5 years (and in some cases now), we will be sequencing the DNA from the cancer of most patients using this technology and giving doctors and scientists the DNA code of each person’s cancer (video of DNA in chromosomes is below). This is extremely important since we know that errors in the DNA code cause the cancer and allow the cancer to thrive. Therefore, if we know what has gone wrong in the cancer’s DNA code, we can then devise a personalized treatment strategy that is tailored to treat that person’s particular cancer. This is a much smarter and likely a more beneficial strategy to treat the cancer. Thus, the Human Genome Project combined with decades of research around the world will bring us into a new era of personalized cancer treatment.
Sequencing the DNA of cancers in a quick and cost-effective manner also has other important treatment implications. From this code we are now learning that cancers which begin in the same part of the body (e.g., all lung cancers) are not as alike as we thought. In other words, even lung cancers that look the same under the microscope, and may in fact behave the same in the patients, are very different on the DNA level. What this means is that we are now seeing cancer not as one disease but many different diseases that may look the same, but are very different on the DNA level. So, if you read that a new amazing cancer treatment can only be given to 5% of people with breast cancer, what this likely means is that those 5% have the type of DNA in their cancer that would benefit specifically from this new treatment. This is not a bad thing but instead a sign that we are getting smarter, more targeted, and personalizing cancer treatment.
Challenges still remain. Even though we know the DNA code, we do not know what a large chunk of the code means. This is where cancer biologists like myself go to work. We are trying to crack the code and figure out what a normal DNA code means and what a cancer DNA code means. Once we have this information, we then try to develop a personal treatment that works against these defects in the cancer. However, just because we know what has gone wrong with the cancer code, does not mean we can always stop it. That is, creating new treatments that target the cancer code is easier said than done. Lastly, there are also non-scientific challenges, such as where will DNA sequences be stored, who “owns” the DNA sequence, who will pay for the sequencing, how will sequencing be implemented in clinical practice, as well as other ethical and privacy issues. Clearly, we need to exercise caution as we enter into this new cancer treatment era.
Even with these challenges, personalized cancer treatment will happen and is beginning now. It is not only me that believes this. I recently participated in a twitter chat hosted by ABC’s @DrRichardBesser. All the major medical schools and research institutions that were participating shared a common agenda of personalized cancer treatment based upon the DNA code of the cancer. Institutions across the world including my laboratory in @winshipatemory are poised to implement new personalized cancer treatments. Cracking the DNA code of cancer is our newest strategy and I propose this is where hope lives for treating cancer over the next decade.