Overcome the Challenges of Cancer Care. M. D. Rosenberg
grow, new changes in the DNA may allow them to grow faster.
Cancer is like a weed. A weed will use any advantage to go after sunlight, water, and nutrients in the soil. In the same way, a cancer cell will use any competitive edge for resources in the body. Weeds do this by growing taller and faster than many other plants to gain more access to sunlight. The deep roots of weeds are difficult to remove, allowing the weed to regrow if it breaks. Cancer cells, like weeds, will try to steal the nutrients from normal organs and cells need to survive. The changes cancer cells go through also allow them to be more resistant to chemotherapy, radiation, or immunotherapy.
Another problem is that cancer cells are so much like normal cells; they’re like closely related cousins. Most of the DNA between a normal cell and a cancer cell is the same. It can be hard to tell the cells apart.
In a garden, you want to make sure any method you use to get rid of weeds—pulling them out, spraying weed killer, etc.—doesn’t remove the local plants too. But at its core, a weed is still a plant. To get rid of weeds, you need to figure out what makes weeds different from other plants. In the same way, the only way to treat cancer is to find some differences between normal cells and cancer cells. Finding and exploiting these differences for treatments is hard.
Cancer’s Achilles’ Heel
Cancer cells have a deep desire to grow and divide. It drives everything they do.
This constant drive to divide is something we use to our benefit in trying to eradicate it. It’s the difference between cancer cells and normal cells. Taking advantage of the cancer’s basic instincts to divide is why chemotherapy and radiation are effective treatments. Some mutations (changes) in the DNA that allow cancer cells to grow also give us unique targets to hit with our expanding list of drugs. We’ll explore this idea in later chapters on types of cancer treatments.
Getting Back to the Basics
To summarize, cancer is common. It’s the unchecked division of cells in the body caused by mutations. These mutations happen because of age, exposures (known and unknown), and lifestyle choices.
Treating cancer is hard because it’s different in different people. It can move to a new part of the body and keep changing. At its core, cancer is just a shadow of us. The cancer cell has a lot in common with a normal cell. But for treatment, we use the cancer’s desire to divide against it.
In the next chapter, we’ll go back to basic biology to further discuss how cancer grows in relation to normal cells. This will give you some context on how cancer therapies work and what their side effects are.
Chapter 2
The Biology of Cancer
To understand the basics of cancer treatment, you need to understand the biology of cancer. With this goal in mind, we’ll review some basic human and cell biology to help you grasp cancer’s behavior. Don’t worry; we’ll keep the science at a sixth- to eighth-grade level. Cancer plays by its own rules, and we’ll outline some of these rules as we go.
How a Normal Cell Behaves
Cells are the building blocks of our bodies. Each cell has a nucleus (the center of the cell) that stores the DNA, the “brain” of the cell. The DNA stays in the nucleus, giving out orders.
DNA stores the instruction manual for each one of us. The DNA needs to convey that information to other parts of the cell, so pieces of those instructions are transcribed, or rewritten, as RNA. The RNA exits the nucleus, and the RNA’s instructions are used to build proteins in the rest of the cell. Proteins then perform the actions of the cell. In short, the information is copied and used in this order:
DNA → RNA → protein
The goal of the DNA is to get the instructions to the protein to carry out actions around the cell. These actions could include instructions to grow, divide, sleep, or anything in between.
Each of our normal cells has a program to tell it to stop growing and die when too much damage occurs to the genetic code (the DNA). This process of self-destruction is known as apoptosis. Cancer cells lack the normal signals telling them to self-destruct.
The process is much more complicated than this, but this explanation gives you a framework for how cells work. You can find the biological definitions of DNA, RNA, and proteins in the glossary at the back of the book.
My Mom Had Cancer . . . Will I get Cancer?
Many patients and family members want to know about their genetic risk of getting cancer. If their mom or dad had cancer, will they definitely get cancer?
Most cancers that occur are random events. They come from a mix of risk factors, like age and exposures in the environment such as smoking. (If you’re smoking, please stop! See chapter 12, on nutrition and lifestyle, for help.) For many cancers, there is likely some genetic component underlying its development. However, it’s only a small part of the risk compared to lifestyle, age, and other factors.
There are genetic syndromes, passed down from parents that increase the risk of getting cancer. These genetic syndromes are rare. Still, they do put people at risk for cancer at a much higher rate. Patients may inherit these risks from mom or dad. An example is a mutation in the genes BRCA1 and BRCA2 that increases the risk for breast cancer and other cancers.
To avoid cancer, some patients with genetic syndromes decide to have organs taken out before cancer develops. Patients with BRCA1/2 mutations may have both breasts and ovaries removed to significantly reduce that risk. This is because these patients are at very high risk of getting a cancer of these organs.
If you or someone you love has multiple family members with cancer, please discuss this with a doctor. By talking to a doctor, you can help make sure you or a loved one get referred for proper genetic testing. Identifying these genetic syndromes may be important for a cancer patient’s siblings or children. A patient should work out a complete family health history before meeting with a cancer doctor.
The Cancer Cell: Making Crazy Decisions
Mutations are what drive cancer. They may come from a random event or damage from the environment. These mutations drive certain behaviors in cancer cells that are unusual.
Imagine that DNA is someone who owns and runs a company. What happens if the owner comes to work not thinking right? Maybe they got bonked on the head and have a concussion or amnesia. In some way, the owner has changed their thinking. Their thinking has mutated.
The owner keeps handing down instructions that don’t make good sense to the company’s managers. Still, the managers pass on those instructions to the employees, who act on them.
This change in thinking corresponds to a mutation in the DNA of a cancer cell. The DNA gives inappropriate instructions to the RNA, which uses them to make the proteins that act throughout the cell.
In the rest of this chapter, I outline the core behaviors of cancer. If you want a technical explanation, check out the paper by Douglas Hanahan and Robert Weinberg listed in the resources at the end of this book.
Business Partners: Keeping the Owner in Line
When cell growth gets out of control, the body has a few systems in place to stop it.
Again, imagine the DNA of a mutated cell as the owner of a company, who’s suffering from amnesia after getting hit on the head. So the owner tells the managers to open new stores or to order more inventory, even though the company doesn’t have enough money to do that. Luckily, the owner’s business partners will try to stop, or suppress, the owner from making these big mistakes. They try to put the brakes on the owner’s awful decisions. There are checks and balances in a company to keep it operating