Chemotherapy and radiation: the same, similar, or something else entirely?

A bag used for chemotherapy and the device used for radiation treatment

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As the second leading cause of death among Americans, cancer has impacted nearly everyone in some shape or form.

Yet despite the statistics – the very topic of cancer still remains a sensitive topic for many, which at times can hinder or even halt the flow of information. On top of that, unless someone has personally experienced cancer treatment, it’s easy to confuse what the best defenses are for fighting it. This is especially true when it comes to chemotherapy and radiation.

Recently, Nick Hanson and Laura Wallenta of the Academic Health Center’s Office of Communications sat down with University of Minnesota Physician Edward Greeno, M.D., the medical director of the Masonic Cancer Clinic. They asked him about the differences between two forms of cancer therapy: chemotherapy and radiation.

He had plenty of information to offer.

AHC: Let’s get the basics out of the way. What is radiation therapy?
Dr. Greeno: Radiation therapy is energy that we deliver to tumors as a way to kill the tumor cells. It can range from what we think of as light photons to particles like electrons or even something as large as a carbon ion.

AHC: And what is chemotherapy?
Dr. Greeno: Chemotherapy is drug therapy. It means chemicals that we deliver as a way to kill tumor cells.

AHC: It sounds like there is a pretty big difference between the two. Why do you think people confuse them?
Dr. Greeno: To a lay person, the terms radiation or chemotherapy don’t really mean much until they’ve had a simple explanation that one is drugs and one is energy, which is sometimes a hard concept for people to differentiate.

AHC: Is there a benefit to one over the other?
Dr. Greeno: So, there isn’t a best between radiation or chemotherapy in general terms. In each individual cancer and even within different stages of the same cancer radiation or chemo or both might be the best choice.

AHC: So can radiation and chemotherapy be combined for better results?
Dr. Greeno: Often we combine radiation and chemotherapy because they have synergistic effects on killing tumor cells.

AHC: Interesting. Can you tell us what the risks are associated with both?
Dr. Greeno: So the main toxicities -- in general terms – from chemotherapy relate to injury from rapid dividing cells. So things like the bone marrow and the lining of the GI track are often damaged.

With radiation it has more to do with direct injury to tissues around the radiated tumor and effectively the injury is a burn to the tissues surrounding the tumor.

AHC: Is it hard to say that one is more toxic than the other?
Dr. Greeno: That’s correct. The toxicities are going to be very dependent on the particulars of the type and dose of radiation and the type and dose of chemotherapy.

AHC: What is the biggest misconception people have regarding cancer therapies like chemo or radiation?
Dr. Greeno: The biggest misperception people have is that chemo or radiation are always going to make you very sick. In many circumstances people get little or no toxicity from treatment and even when they do get toxicity it is something we can manage. So really patients need to think carefully and talk carefully with their doctor about the details of what’s going to happen with their particular chemotherapy or radiation.

--- Laura Wallenta and Nick Hanson