Dear Doctor: A close relative had extensive radiation therapy for an early breast cancer. The treatment was effective, but it damaged the surrounding tissues, including her aortic valve. What are the potential side effects of radiation therapy?

Dear Reader: Radiation therapy, also known as radiotherapy, is a type of cancer treatment that uses intense beams of energy to kill cancer cells. Most often, it uses X-rays, a type of electromagnetic radiation, but a newer type of therapy uses protons. These are subatomic particles that carry a positive charge. Although both approaches to radiation therapy are effective at killing cancer cells, each can cause a range of side effects. These vary from person to person and depend not only on the type and location of a person’s cancer, but also on their general health as well.

Unlike chemotherapy, which is systemic, radiation therapy is a highly localized treatment. A person’s tumor is mapped, and the beams of energy are precisely focused on the area. Even so, surrounding healthy tissues are often damaged. Due to the physical properties of protons, that type of radiotherapy can be successful at sparing surrounding tissues. However, proton therapy isn’t widely available and can’t be used for all cancers. Radiation therapy with X-rays, while successful at killing cancer cells, can also cause damage to healthy tissues.

Radiation therapy sessions last about 15 minutes and are not painful. Treatment is administered five days a week and lasts from three to nine weeks, depending on the cancer. The energy used to kill the cancer cells is quite powerful and, over time, the nearby healthy tissues tend to sustain damage. This results in a range of side effects. A common one is fatigue, which begins during the course of treatment and can persist for several weeks or months after treatment has ended. Many people develop skin problems such as dryness, itching, blistering or peeling in the site where the radiation is delivered. Depending on the part of the body receiving the treatment, additional side effects can include swelling, or edema; hair loss; nausea; trouble swallowing; diarrhea; problems with urination; or changes to taste.

When heart muscle is exposed to radiation therapy, as happens in treatment for breast cancer, Hodgkin lymphoma and cancers of the lung or esophagus, injuries can occur. These can include the heart valve injury that your relative experienced, as well damage to the coronary arteries, the tissues that cover the heart, the specialized cells that control heart rhythm and the heart muscle itself. These injuries can develop in the days and months after treatment, but are most often seen a year or more later.

The good news is that advances in radiotherapy over the years have lessened the incidence of cardiac injury. In addition, modern treatment protocols are often performed in partnership with a cardiologist. Their job is to assess a patient’s risk of heart injury prior to treatment and to monitor their progress during the course of radiotherapy. The goal is to craft an effective cancer treatment that doesn’t cause more health problems than it solves.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: After three planned children and one unexpected (but much-loved) arrival, my wife and I think a vasectomy is a good idea. What will happen? How permanent is a vasectomy?

Dear Reader: A vasectomy is a safe and effective kind of birth control that works by disrupting the pathway that carries a man’s sperm. This is done via a simple elective surgery in which the vas deferens, which are the two tubes that carry sperm from the testicles to the urethra, are cut or blocked. The procedure, which is usually performed by a urologist, is close to 100% effective, with just one or two pregnancies per 1,000 procedures. The surgery can be reversed, but the success rate of future pregnancies varies.

A vasectomy is done on an outpatient basis, either in the urologist’s office or a surgery center. It’s likely that your doctor will ask you to avoid blood-thinning medications in the week leading up to the surgery. These include non-steroidal anti-inflammatory drugs (NSAIDs) such as aspirin and ibuprofen, and also may include prescription drugs such as warfarin and apixaban. This is done to limit bleeding during the procedure. It’s important to note that you should never stop taking prescription blood thinners without first consulting with your doctor.

The procedure itself is done under a local anesthetic, so the patient is awake. In the traditional method, the surgeon uses a scalpel to make either one or two incisions in the scrotum in order to reach the vas deferens. A segment of each tube is cut away, and the open ends are sealed shut, either by cauterization or with stitches. The incisions in the scrotum are also closed up.

A newer type of vasectomy, known as the “no-scalpel” method, uses a small puncture to access the vas deferens. Studies suggest that the no-scalpel method results in less pain and fewer post-surgical complications, including infections and blood clots. Additional complications can include pain, swelling, bruising and blood in the semen. Delayed complications can include post-vasectomy pain syndrome, or PVPS. This is prolonged post-surgical discomfort or pain and occurs in 1% to 2% of cases.

Following the surgery, you’ll be asked to wear a supportive garment, such as a jock strap or tight-fitting underwear, for a day or two. Ice packs will be used to reduce swelling, and your doctor will advise you on any pain meds you may need. It’s important to rest for a day or two after surgery, and then to limit activity, such as sports or heavy lifting, for at least a week beyond that. If at any time you experience signs of infection, call your doctor immediately. These include fever and redness, swelling or discharge at the surgical site that don’t improve.

Sperm continues to be present after a vasectomy. That means it’s important to keep using birth control until a follow-up semen analysis, performed six to 12 weeks after the procedure, gives you the all-clear. And remember, although a vasectomy will prevent pregnancy, it doesn’t protect against sexually transmitted diseases. Anyone outside of a monogamous relationship should continue to protect themselves with condoms.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: Our mom is 66 years old and has always been healthy. She was diagnosed with atrial fibrillation during her last physical. She says she feels fine, so she hasn’t followed up with her doctor. What can happen if she doesn’t get treatment?

Dear Reader: Atrial fibrillation is a common heart rhythm disorder, or arrhythmia, that affects anywhere from 2.5 million to 6 million people living in the United States. Also referred to as AFib or AF, the condition causes a rapid and irregular heartbeat. People living with AFib have an increased risk of stroke, heart failure and other heart-related complications. The good news is that there are several effective treatment avenues for the condition. Without treatment, however, the symptoms of AFib often get worse.

The condition gets its name from an electrical malfunction in the upper chambers of the heart, known as atria, which pump blood into the ventricles, the two lower chambers of the heart. It occurs due to a glitch in the sinus node, a cluster of specialized cells in the upper wall of the right atrium, which act as the heart's natural pacemaker. Instead of producing a steady, rhythmic contraction, the atria quiver, or fibrillate. The result is a disorganized heartbeat, rapid and irregular, which interferes with optimal blood flow. It often causes blood to pool in the left atrium, which can lead to the formation of blood clots. If a blood clot breaks free, it can circulate and block blood flow to other parts of the body. A blood clot that travels to the brain can cause a stroke.

Many people with AFib -- and it sounds as though your mother may be one of them -- don’t experience any noticeable symptoms. Those who do will feel a jittery, racing heartbeat; the sensation of a skipped heartbeat followed by a “thump” within the chest; exhaustion; shortness of breath; dizziness; chest pain or pressure; or unusual fatigue during exertion. The condition runs the gamut from mild to severe. Occasional episodes, known as paroxysmal AFib, last from a few seconds to a few hours, and the heart recovers on its own. AFib that requires medication or an electric shock to return to normal rhythm is labeled as persistent. Permanent AFib is when normal heart rhythm cannot be restored.

Treatment depends on which specific type of AFib a person has, as well as on any additional medical issues that may be present. In all types of AFib, the dual goals are to restore normal heart rate and to prevent blood clots. Medications such as digoxin, beta blockers and calcium channel blockers may be used to restore heart rate. Blood thinners, including Warfarin and newer anticoagulants, are often prescribed to prevent stroke. If medications don’t work, procedures to inactivate the sinus node cells causing the arrhythmia may be used. In some cases, a pacemaker is the best option.

Even though your mother can’t feel the symptoms of her AFib, the condition is dangerous when it goes untreated. We strongly urge her to see a cardiologist and begin a potentially lifesaving therapy.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)