Prostate cancer: Radiation therapy increases the risk of future cancers

The risk is small, but you should discuss it with your doctor.

A standard treatment for localized prostate cancer – i.e. h. Cancer limited to the prostate gland – consists of killing or shrinking tumors using radiation. The long-term results for most men treated this way are excellent. But like other cancer treatments, radiation comes with some risk, including the possibility of secondary cancers forming later in the body.

Secondary cancers are defined based on whether they meet certain criteria:

• sie unterscheiden sich von dem Krebs, gegen den ein Patient ursprünglich behandelt wurde
• sie treten innerhalb des bestrahlten Bereichs auf
• sie waren vor Beginn der Strahlenbehandlung nicht vorhanden
• sie treten frühestens vier Jahre nach Abschluss der Behandlung auf.

Historical evidence shows that secondary cancers occur rarely. Now a large study of men treated with current radiation methods used in modern times updates that conclusion.

Study data and results

Investigators reviewed data from 143,886 men treated for localized prostate cancer at Veterans Affairs medical facilities between 2000 and 2015. The men were between 60 and 71 years old and came from a variety of racial and ethnic backgrounds. 52,886 of them received radiation within one year of diagnosis. The other 91,000 men either opted for surgery over a similar period of time or chose to have their cancer monitored and treated only when – or if – routine tests showed signs of progression.

After a median follow-up of nine years, 3% of men who received radiation had developed secondary cancers, compared with 2.5% of men who chose other options. The four most common cancers - in order of frequency of detection - were bladder cancer, leukemia, lymphoma and rectal cancer. The risk of developing these secondary cancers increased steadily over time, peaking five to six years after radiation treatment was completed.

Dr. Oliver Sartor, an oncologist at Tulane University School of Medicine in New Orleans who was not involved in the study, says the potential for secondary cancers is an important topic that men should discuss with their doctors when evaluating treatment options.

Weigh up the risk

Unfortunately, doctors are limited in their ability to predict which men treated with radiation are at greatest risk of secondary cancer. Smoking is a major risk for bladder cancer, "so men who smoke while undergoing radiation have another reason to quit," says Dr. Sartor. Men with hereditary risks of Lynch syndrome (a form of colon cancer) are also at higher risk of radiation. These men have gene mutations that make it harder for their cells to repair DNA damage.

Dr. Marc Garnick, Gorman Brothers Professor of Medicine at Harvard Medical School and Beth Israel Deaconess Medical Center and publisher of Harvard Health Publishing, notes that Dr. Sartor presents excellent and actionable argumentsAnnual report on prostate diseases,agrees that patients considering radiation should be informed that the treatment puts them at a small but real lifelong risk of secondary cancer, particularly of the rectum and bladder, which may occur years after radiation therapy is completed.

Dr. Garnick says he is hesitant to consider radiation for men with a history of inflammatory bowel disease such as ulcerative colitis, who also have a higher risk of developing abdominal cancer. He also advises older men who have had radiation for prostate cancer to consult their doctor before completing routine colonoscopies.