Radiation Injuries from Cancer Treatment

What is radiation therapy?

The most common form of radiation therapy uses beams or streams of high-energy photons, or x-rays, to treat cancers in many body parts. A machine, called a linear accelerator, creates the photons to divide parts of atoms and create “beams” of energy, x-rays, that travel through the body tissues and into the cancerous mass. The x-ray beams cause damage to DNA in the cell (the building blocks of the body’s tissues), which the cell cannot repair, and this damage affects the tumor and the surrounding normal tissue. As a result, some cells die immediately, and some do not show injury until they begin to grow and divide again. Additionally, the radiation energy can create other toxic substances, called free radicals, which interact with the cell’s DNA and cause irreparable damage. With technological advances, radiation has become more effective by increasing the intensity of energy delivered to the tissues. A radiation oncologist designs treatment plans and uses a particular machine to direct the x-ray beams to the malignant tumor and limit the damage to the surrounding normal tissue. Radiation therapy delivered as an external beam is called external beam radiation therapy (EBRT). Newer types of EBRT, such as intensity-modulated radiation therapy (IMRT) or proton beam treatment, can better control where the x-ray beam travels to limit how deep the energy travels into the body and minimize damage to body structures.

Brachytherapy is a second form of radiation therapy that delivers radiation directly to the tumor in the affected organ using radioactive elements or “seeds” placed directly into the tumor. Radiation oncologists can deliver higher doses of energy directly to the tumor and lower doses to the surrounding normal tissue with the radiation source inside the cancer. Because the pelvis is a compact body cavity, some radiation energy will enter other structures very close to the radiation target regardless of the type of radiation delivered. Thus, side effects and complications of radiation therapy result from x-ray radiation damaging normal tissues.

Early treatment side effects

Prostate Radiation: The prostate is a leading site of new cancer diagnosis in men. Doctors use both EBRT and brachytherapy to treat prostate cancer. Unfortunately, about 20% of men who receive EBRT have some immediate side effect of the urinary system and about 10 % have symptoms of the lower intestinal system, i.e., rectum or anus. Urinary side effects include burning with urination, straining with urination, or incontinence. Intestinal side effects include rectal spasms and staining with bowel movements.

Patients who received brachytherapy have similar symptoms, although the exact percentage of men who have problems is unknown. The most common symptoms are frequent urination, burning with urination, and slow stream. Intestinal side effects include diarrhea and rectal spasms.

Men who receive a combination of seed implant and EBRT have a significantly higher incidence of symptoms, including burning with urination, frequent urination, and inability to urinate. Intestinal side effects are predominantly diarrhea and rectal spasms.

Bladder Radiation: Bladder cancer invading deep into the layers of the bladder is usually treated with surgery to remove the bladder. Some patients may receive a combination of endoscopic surgery, chemotherapy, and EBRT to treat bladder cancer and preserve the bladder. About one-third of patients with radiation treatment to the bladder develop symptoms that include frequent or urgent urinary, urinating at night, burning with urination, and leakage of urine. In addition, approximately 20% of patients treated with radiation therapy for bladder cancer develop intestinal side effects like diarrhea and rectal spasm or pain.

Treatment of Early Side Effects

Urinary symptoms: If these side effects happen, they increase the most during active treatment, and most resolve 1-3 months after treatment ends. Typically, doctors use medications to treat side effects early in treatment. For example, patients who notice a slow urinary stream or strain to urinate are treated with medication to relax the muscle tissue in the prostate. Another treatment option is behavior modification. Frequent or urgent urination responds well to simple strategies like emptying the bladder on schedule, often every 4-6 hours, and eliminating foods that irritate the bladder. Your doctor will provide you with a list or groups of foods that irritate the bladder if you experience these symptoms. Persistent symptoms may require medications to decrease the sensation of the bladder and lessen these symptoms. Patients with burning on urination, often coupled with a frequent or urgent need to urinate, are treated with various treatments, including medication to decrease inflammation, like ibuprofen, pain medication specific to the bladder, and the addition of drugs listed above.

Intestinal symptoms: If these side effects occur, they can also worsen during the active phase of treatment. Most symptoms resolve 1-3 months after active treatment ends. Steroid creams and suppositories treat symptoms like rectal pain or spasm well. Diarrhea may be the result of bacterial infection. The next step is to decrease the intake of dairy and fiber. Medications are effective in treating persistent diarrhea. Your doctor can discuss the specific plan based on your symptoms.

Chronic radiation side effects

Radiation cystitis: This condition results from loss of blood supply to the lining of the bladder due to scarring of the small blood vessels that feed the tissues that line the bladder, known as mucosa. With a loss of blood supply, tissues receive less oxygen. As a result of the inflammation and loss of blood supply, scar tissue replaces healthy tissue. This condition is known as radiation cystitis. Symptoms include bleeding, blood clots in the urine, frequent urination, urgent need to urinate, or incontinence. On average, these complications happen at least 35 months after the completion of radiation and occur in 3-9 % of patients treated for bladder, prostate, or cervical cancer. Radiation cystitis is challenging to treat and may require medications, high-concentration, or “hyperbaric” oxygen therapy, and occasionally surgery. Rarely, severe symptoms, such as bleeding in the bladder, can be life-threatening.

Lower Urinary Tract Symptoms: These symptoms are commonly associated with urinary blockages, like in men with enlarged prostates. Typical symptoms include a weak urinary stream, straining to urinate, feeling that the bladder is not emptying, and frequent or urgent urination. This complication results from inflammation of the bladder tissue that happens years after radiation therapy. Treatments will include medications to relax the bladder, decrease bladder sensation, and avoid foods or drinks irritating the bladder. If these first steps do not improve the symptoms, your doctor can discuss other, more invasive treatments or surgeries.

Urethral Stricture or Bladder Neck Contracture: These problems arise due to the accumulation or growth of scar tissue in the urethra, the tube that drains the bladder, or the opening of the bladder, the bladder neck. This scar tissue forms because of inflammation and lack of blood supply. It occurs in approximately 2-6% of patients (about 1 in 20 persons) following various types of radiation treatment. To fully evaluate symptoms that result from these problems, patients may undergo diagnostic procedures such as endoscopic evaluation of the urethra and bladder, cystoscopy, or x-ray studies of the urethra or bladder. Additionally, patients need to have functional testing on the bladder, called urodynamics, to ensure the bladder functions before undergoing any treatment. Standard procedures to open or remove the blockage include endoscopic surgeries to incise or open the scar tissue, dilate scar tissue, or complete surgical excision and reconstruction called urethroplasty. The urethroplasty page on the TURNS website has more information and details about the surgery.

Bladder or Urethral Fistula: Fistulas are abnormal connections or openings in specific hollow organs of the body. Fistulas in the urinary system commonly involve the urethra or bladder and result from tissue damage from radiation. Due to a lack of blood supply in these radiated parts of the urinary tract, progressive inflammation, and repeated infection cause the urethra or bladder wall to break down and form a connection to surrounding body parts. These structures include the rectum, pubic bone, vagina in female radiation patients, and skin of the thigh or perineum, the area of skin between the scrotum and anus in male patients. The symptoms of urinary fistula can include recurrent urinary tract infections, leakage of urine into the rectum or vagina (in female patients), thigh or hip pain, and skin or bone infections if the fistula tracks to either of these body areas. Severe complications like fistulas occur in fewer than 1 in 1000 patients who receive modern external beam radiotherapy but in about 1 in 100 patients who receive high-dose-rate brachytherapy.

The initial treatment of fistulas is diverting the urine stream away from the fistulized area using urinary catheters or tubes inserted directly into the kidneys through the back, percutaneous nephrostomy tubes. If the fistula connects to the rectum, the fecal diversion, with a colostomy, is performed. In this surgery, the colon or small bowel is brought up to the skin and sewn in place. A stoma bag is pasted to the skin to collect the feces. These diversions are temporary until chronic infections resolve and surgical fistula repair is complete. Often patients need to wait between the colostomy placement and the fistula repair to allow infection and inflammation to resolve. Occasionally fistula will heal spontaneously with only the colostomy surgery. Each fistula is different and needs complete evaluation using cystoscopy, x-rays of the urethra or bladder, mentioned above, and a CT scan of the abdominal cavity and pelvic structures.

Fistulas, especially connections of the urethra to the rectum, are amenable to reconstructive surgical repair. The closure of the fistula and placement of a muscle or tissue flap between the rectum and the urethra can repair most fistulas. Muscle or tissue flaps are essential for successful surgery since these, with good blood supply, fill the space between the urethra and rectum with healthy tissue. Repair of fistulas involving the bladder is similar. The hole connecting the bladder and the rectum or vagina is closed, and healthy tissue is placed between the two openings to separate them. However, surgical repair may not be possible if the fistula is too large, or the damage is too severe. In this case, your urologist may recommend surgical removal of the bladder and a permanent urinary diversion to drain the urine from the body.