Weeks 128 & 129: Why do people get cancer and how to try to cure it?

Written by Lars Haakon Soraas
11
Feb

Weeks 128 and 129 in the war on lung cancer have passed. As there is not too much to report, I will in this post mention two interesting research articles that recently came out. But first the update:

  • Dyanne has been in pretty good shape. She still has some fatigue, but the stomach issues are much better.
  • Her hemoglobin is still a bit low, and eosinophiles are still high. However, both seem to (hopefully) be moving in the right direction.

Then to the two research articles. The first article is by some mathematicians in the UK. They have looked at the incidence rate of cancer and tried to explain why older people get so much more cancer than younger people. The leading explanation today is a theory put forward by Professor Bert Vogelstein of Johns Hopkins and others. In short, they belive that cancer is primarily caused by random mutations which occur when cells divide. This theory states that it takes around 3 mutations to cause cancer and the reason older people get cancer more than younger people is that it takes time for any cell to accumulate the three required mutations. This theory fit the incidence data pretty well.

The new paper that has come out partly agrees with Vogelstein and co. However, they claim that a weakening immune system is also a major reason for increased incidence of cancer with age. Specifically they claim that the thymus, an organ which produces immune cells, over time decreases its output of new immune cells. This gradually causes our immune system to weaken and this makes it easier for cancer cells to avoid being wiped out by our immune system. Through some mathematical modelling they show that their hypothesis is even better at explaining the cancer incidence data than the theory of Vogelstein. Note that these mathematicians still believe the mutations are integral parts of what causes cancer. Their modelling suggests, however, that it really only takes 2 mutations to cause cancer, and not 3. And, unlike Vogelstein and co, they believe that a declining immune system plays an important role in cancer etiology.

Maybe one reason I found the paper so interesting is that it uses words like “random walk” to describe how and why cancer happens. Random walks will be easy to understand for anyone who has studied finance, so if you are a math or finance geek, you may like the paper as much as me. The paper is open access (i.e. not behind paywall) and can be found here:

Thymic involution and rising disease incidence with age

A layman’s version can be found in this BBC article about the paper:

Ageing immune system linked to cancer

The second paper I wanted to mention is by a group in Tübingen in Germany. They have treated a pancreatic cancer patient with a personalized peptide vaccine that is, essentially, very similar to the vaccine Dyanne is getting in Frankfurt. The patient is still alive and well, 6 years after diagnosis. He has no signs of cancer and is in good health. Pancreatic cancer is pretty bad. Actually very very very bad. It is one of the few cancers which have worse survival rates than lung cancer. As a doctor once told me: “there are no lobby groups for pancreatic cancer patients; they die before they manage to organize”. So a patient living 6 years after diagnosis is good news. The article does not prove that the patient’s good condition is due to the vaccine. Maybe it is all a lucky coincidence. One should, of course, be very aware of “survival bias” in the medical literature. Patients who got similar treatment, but died, are not so much fun to write about. In any case, the article does add to the evidence base which suggests that personalized cancer vaccines can be beneficial for cancer patients. According to my count, it is the 4th paper published on which describe patients who have received such vaccines.

The paper is open access and can be found here:

So maybe accumulating, and largely random, mutations combined with a weakening immune system are the main reasons people get cancer. And maybe the way to treat cancer is by personalized vaccines. Time will show.

Have an interesting Sunday evening!

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