Long-term side effects of radiation therapy

If you have undergone radiation therapy (radiotherapy) for cancer treatment, it's normal to have concerns about potential long-term side effects. Fortunately, not everyone experiences side effects and for those who do, side effects are rarely serious. Adam Nowlan, M.D., a Piedmont radiation oncologist, explains radiotherapy benefits, common post-treatment signs, and when to see your doctor.

The benefits of radiation therapy

"While there is a risk of long-term side effects, radiation therapy is perhaps uniquely capable in the field of medicine of sterilizing microscopic disease that is embedded in normal tissue without necessarily having to cut out the normal tissue," says Dr. Nowlan. "Radiation can reduce a microscopic cluster of cancer cells into something that is nonviable. We are treating an invisible disease with invisible beams. We can treat cancer cells that remain even after chemotherapy or surgery, or shrink tumors before surgery or chemotherapy. Radiation therapy is capable of helping someone who could have died from cancer and giving them their life back."

Why does radiation cause long-term side effects?

"The reason radiation therapy works is because it damages the DNA of cells," he says. "Rapidly dividing cells, such as cancer cells, are more affected by radiation therapy than normal cells. The body may respond to this damage with fibrosis or scarring, though this is generally a mild process and typically does not cause any long-term problems that substantially affect quality of life."

Radiation oncologists are trained to deliver the right dose of radiation to the right body part on the correct schedule. They aim to reduce side effects and limit radiation exposure, delivering an effective dose to target cancer cells while protecting healthy tissue.

Who is at risk for long-term side effects of radiation therapy?

This varies from person to person. Your risk of long-term side effects may increase with the amount of radiation you receive. Some people have a rare inherited disease that causes them to heal poorly from radiotherapy.

"If we discover a patient has this type of inherited disease or conditions such as scleroderma, we try to avoid radiation when treating their cancer," says Dr. Nowlan.

What are the most common long-term side effects of radiation?

"Generally, the side effects of radiotherapy are related only to the area of the body that was treated," says Dr. Nowlan. "The only long-term side effect of radiation that occurs outside the area that was treated is some lingering mild fatigue, which typically fades within three to six months."

He breaks down the most common potential side effects by the body part treated with radiation therapy. Consult your doctor about your individual risk, as each person is unique.

• Breast: 

  • Minor scarring of the lung that can show up on an X-ray

  • The treated breast may be slightly smaller and firmer, though this is rarely noticeable, even in a bra or swimsuit

• Head or neck:

  • Changes in saliva pH can promote harmful bacteria, increasing the risk of enamel damage and cavities

  • A permanent alteration in taste or food preferences

  • Bone injury (Avoid dental surgery or other dental work after treatment.)

  • Difficulty swallowing

  • Mouth dryness

  • Throat pain or hoarseness

  • Tightening of the jaw

• Brain:

  • Cataracts

  • Hair loss

  • Hearing loss

  • Memory loss ("It's hard to determine how much memory loss or cognitive dysfunction is related to a tumor and how much is related to radiotherapy," says Dr. Nowlan. Radiation oncologists minimize brain exposure by using precise treatments such as Gamma Knife and stereotactic radiosurgery.

• Pelvis:

  • Increased, looser bowel movements

  • Infertility (For patients who wish to have children one day, there are options to preserve fertility prior to treatment.)

  • Reduction in bladder capacity

  • Vaginal dryness

• Chest:

  • Increased risk of breast cancer for patients who receive chest radiation for conditions such as lymphoma during puberty

When to contact your doctor

If long-term side effects occur, they typically develop within two to three years of treatment. It is rare for a symptom to pop up eight to 10 years later. If you experience one of these symptoms, contact your primary care physician or radiation oncologist.

Learn more about cancer treatment, prevention, screenings and side effects.