1.1 What is Cancer?

Slide 1
[Slide title: What is Cancer?] I’m Rolf Renne, and today I will share with you some basic facts about cancer.

Slide 2
The session topics I will cover in the next few minutes are some definitions and some nomenclature, or terminology, the incidence of cancer in the United States, the way cancer arises from a multi-step process, and then some hallmarks, or characteristics, which are common to all cancer cells, and ending with the concept that cancer is not really one disease, but many different diseases.

Slide 3
So the definition and terminology: Cancer is broadly defined as a disease that is caused by uncontrolled division of cells. And I think this is a really important point. I like to illustrate this in an example. Like for example, if you’re doing sunbathing and your skin gets damaged by UV light, and the cells start repairing your skin; in a healthy individual, these cells know when to stop growing when the healthy skin is restored. However, in cancer, these cells do not know when to stop. And then they grow out to uncontrolled cancer growths.

Sometimes cancer is also referred to in other terms, which you may hear by a physician, referring to neoplasm, which means new growth. Tumor, is the mass of dividing cells or malignancy. And sometimes you hear the term benign or malignant tumors. There could be some benign tumors, but most of them when we talk about cancer, we mean malignant ones.

Slide 4
The incidence of cancer is the second leading cause of death in the United States only surpassed by heart disease. Nearly one in two men and more than one in three women will be diagnosed with some form of cancer in their lifetime. Although through research and through new therapeutics, the survival rates have strongly improved over the years, about 500,000 deaths annually are still caused by cancer in the United States alone.

Slide 5
[Image shows a medieval illustration of a crab, reflecting the origin of the term “cancer.”]
A little bit of history: Why are we calling this disease cancer? This is a very, very long and old recognized disease, thousands of years before BC, people have written about cancer, but specifically Hippocrates, 400 BC, likened the long veins of blood vessels radiating from some breast tumors to the limbs of a crab, which he depicted in the classic picture to the left and “cancer” in Latin means actually “crab”. So that’s where the term comes from.

Slide 6
[Diagram shows tumorigenesis as a multi-step transformation process from a healthy cell to cancer, influenced by multiple damaging factors.]
One concept which is really important to understand for cancer is tumorigenesis, which is also described as the process of how cancer arises in a multi-step process. I’ve pointed this out as a linear line here going from the left to the right from a healthy cell to an immortalized cell, and that term refers to the fact that the cell has lost the ability to die, so it grows forever into a transformed cell, which is a fully cancerous cell or tumorigenic cell, which causes cancer in the individual and also has a lot of other features which we will touch upon very soon. The clear thing about the multi-step process is that it can be very many different things: Injuries, damages, lifestyle factors, all of those will be discussed in following presentations. And all this occurs on a background of what we bring to the table when we were born: our genetic code. So we’re going to be born with some limitations which predispose some people for certain cancers and others less that way. But it’s always the mixture of that and the multi-step process, which leads to cancer.

Slide 7
[Diagram shows a circular model of shared cancer cell characteristics, including uncontrolled growth, survival, and spread.]
So on the next slide, which seems a little complex at first, I would just like to explain some hallmarks, or characteristics, which are common to all cancer cells, and this is depicted in this circle of cancer hallmark features on the right. Starting on the top with the green box- unregulated cell growth. We talked already about this, this is the hallmark feature of why cancer is cancer. Going around clockwise, you can see that there are two different ways how this can occur, that either the cells can grow whenever they want to grow and they also cannot react to “stop” signals anymore. And again, I gave you this example early on with the sunbathing, when your cells touch each other in the healthy skin, they stop growing. The cancer cells grow on top of each other, and cause cancer. I won’t go through this entire cycle but will point out two more things: one important thing to understand, which is very important in the clinic, is tissue invasion and metastasis. This means that tumor cells grow in places in our body where they’re not supposed to be, for example, if you have a breast cancer tumor in a late stage, it can cause metastasis in the bone, and then later, in the brain, and obviously, once this has happened, it’s very hard to combat these cancers therapeutically. Cancer cells are altered in ways that they grow without control and evade host surveillance mechanisms. It’s important to understand that these cancer hallmarks, which are present in all cancer cells, can arise by very many different changes, it’s not just one change which makes the cell grow forever. There could be very different ways which lead to that same point, which we call cancer hallmarks.

Slide 8
And as a result, it is really important to understand that cancer is really not one disease, it’s many hundreds, if not thousands, of different diseases. I cannot tell you often I’ve sat somewhere waiting for a plane or for a train and people ask me, “What do you do for a living?”, and I say “I do cancer research” and they say, “When are you going to cure it?” And that’s the thing to understand. It’s not one cancer; It’s very many. This is true for breast cancer, lung cancer, prostate cancer, and blood cancers like lymphoma and leukemia. As a result, our doctors and scientists work on the cure of many hundreds if not thousands of diseases that require individual therapeutic approaches, and in some cases, we have been very successful already, and in others, it’s a slower process. That’s why, overall, the cancer survival is going up in the United States and in the world.

Slide 9
So, in summary, cancer is caused by uncontrolled growth of cells, There’s about 500,000 cancer deaths still in the United States alone every year. The process of tumorigenesis, is as a multi-step process, which requires different damages to our tissues to occur. We discussed the hallmarks of cancer cells, and we learned that cancer describes a huge number of related, but also very different, diseases and with this I would like to thank you for your attention.