Bonus post: What Does Radiation Therapy Feel Like?

Q: What does chemo/radiation feel like? My character has colorectal cancer.

Last week, we tackled the chemotherapy end of this question. This week, let’s take a deeper look at radiation therapy.

Part 2: Radiation Therapy

The short answer is that radiation doesn’t feel like anything. We experience radiation every day from the sun, space, the earth, even the air. The amount of radiation you’d get from an X-ray is about the same as flying across the country in an airplane. Even a CT scan, or ‘CAT-scan’, which blasts your body with as much as 500 times that of a normal chest X-ray, doesn’t feel like anything¹.

But targeted radiation, used alone or in conjunction with chemotherapy to treat cancer, is given in much higher doses. At these higher doses, your character will start to get side effects. But first, let’s give some background.

Radiation

Radiation kills cells by damaging their DNA, making it impossible to continue dividing. Like with chemotherapy, rapidly dividing cells–such as cancer cells–are the most heavily affected. But since all cells need their DNA, all cells can be affected.

Radiation dosage is given in units called Grays (Gy). One Gray is the amount of energy absorbed by a set amount of tissue (1gray = 1joule/kg)². A chest X-ray administers about 0.1milligrays (0.1mGy or 0.001 Gy). A chest CT delivers around 6 mGy. Someone getting radiation therapy for breast cancer could get as much as 60Gy over several serial sessions³: that is the equivalent of 600,000 chest X-rays! It’s important to note that this absurdly high dose is targeted to a very small part of the body, and is given over multiple sessions. The lethal dose–aka the dose at which 50% of the population would die–of whole-body irradiation is only about 5Gy⁴.

Radiation Therapy

Not every cancer is treated with radiation therapy. Colon cancer is an example of a type of cancer that is rarely treated with radiation, because it usually responds well to chemotherapy and surgery alone. In contrast, larynx and prostate cancer, are often treated with radiation alone–no chemotherapy, no surgery. However, many other cancers, like breast, lung, and rectal cancer, use a combination of chemotherapy, surgery and radiation therapy. If radiation is used in conjunction, it is called “adjuvant radiation.”

Radiation can also be used as a palliative tool to shrink a tumor that can’t be excised surgically. This helps your character feel more comfortable, even though there’s no longer hope of a cure. If your character has colon cancer, this is the type of radiation therapy they would likely receive.

Types of Radiation Therapy

There are two main types of radiation: external beam and internal⁵.

External beam radiation comes from a loud, noisy machine that whirs and clacks–but will never touch your character. It’s targeted to the specific area of the body where the tumor is, such as the breast, prostate, lungs, or thyroid. If your character gets external beam radiation they do not become radioactive, and so have no limits on visitation. In fact, your character might even get to go home between treatments.

Internal radiation is when something radioactive is placed in your character’s body. It can be localized–a little capsule or ribbon surgically placed near the tumor – or systemic, if your character swallows or is given an IV with radioactive materials. If your character received systemic radiation, their bodily fluids – sweat, urine, saliva, even semen–will be radioactive. Anyone visiting someone with internal radiation will need to stay at least 6 feet away and limit visiting time to less than 30 minutes per day. Kids under 18 and pregnant women can’t visit at all.

All right, now I can actually start to answer your question. Let’s start with what it feels like to get the radiation.

The Process

Getting radiated is time-consuming. In order to get up to that 60Gy dose by external beam radiation, your character will need to receive radiation treatment every day (sometimes twice a day), five days a week, for five to eight weeks³. The doctor in charge of your character’s radiation therapy is called a radiation oncologist. They’ll work with your character’s primary oncologist, as well as radiation oncology nurses, dosimetrists – who help calculate the appropriate dose of radiation – and technicians to develop and carry out your character’s treatment plan.

On the day of, your character will be very carefully positioned so that the radiation hits the exact right place–which will be marked with pen on their skin. Then, lead blocks or shields will be placed to protect the rest of their body from the radiation. Once in place, the actual irradiation only takes about 10-30 min. Even with the high dose, your character won’t be able to feel the radiation at all, just some discomfort from the positioning, and possibly some skin redness and tenderness⁶. This may become more prominent as the radiation treatments continue.

Side Effects

Because radiation therapy is a targeted treatment, there are very few whole-body or long-term side effects. Your character may feel some fatigue, especially if they’re also getting chemotherapy. They also might develop skin redness, tenderness, and even blistering around the site. Other than that, all of the side effects of radiation depend on the location being radiated. Here’s a list⁷.

Head and neck
- Fatigue
- Headache
- Blurry vision
- Hair loss
- Dry mouth
- Trouble swallowing
- Cavities or loose teeth.
- Mouth sores
Chest/Breast
- Swelling/tenderness
- Trouble swallowing
- Shoulder stiffness
- Nipple soreness
Abdomen
- Appetite loss
- Nausea/vomiting
- Diarrhea
Pelvis
- Diarrhea or bleeding from the rectum
- Menopause-like symptoms
- Infertility or decreased fertility
- Sexual dysfunction
  - Erectile dysfunction
  - Vaginal dryness
  - Decreased libido
- Inability to control urination (urinary incontinence), or bladder irritation

Most of these symptoms are not dangerous and will go away once the radiation treatment is complete. One exception is called radiation pneumonitis, a cough and fever that occurs up to six months after radiation treatment to the chest, and can leave scar tissue in the lungs.

It’s important to note that if your character is also receiving chemotherapy, or if they recently had surgery, they will simultaneously be struggling with those side effects. Don’t forget to look at last week’s post to see what chemotherapy might feel like!

Drop a comment if you have any questions or suggestions!