When cancer patients are treated with radiation, it is feasible that the therapy itself may cause recent tumors to form later within the body. Radiation kills cancer cells by damaging their DNA, but when the treatment causes genetic damage to normal cells near the goal of the radiation, there may be a small risk that over time it would turn out to be secondary. Errors may occur.
Just 10 years ago, Canadian researchers got down to assess the chance of secondary malignancies in men with prostate cancer who were treated with a kind of radiation called brachytherapy. Unlike radiation delivered from sources outside the body, brachytherapy is achieved by injecting dozens of radioactive pellets, or “seeds,” directly into the tumor site. The seeds, that are never removed, emit radiation at a dose that decays to zero over a 12 months.
Brachytherapy has the advantage of convenience. Instead of traveling for repeat radiation sessions, men only need one treatment, which is often given in an outpatient setting. But brachytherapy can also be falling out of favor, partially because recent forms of external beam radiation deliver highly precise doses with fewer negative effects.
Study Methodology and Results
A Canadian study compared rates of secondary pelvic malignancy in men treated with brachytherapy or with surgery to remove the prostate. All treatments took place between 1998 and 2000 in British Columbia. The brachytherapy group included 2,418 men with a median age of 66 years, while the surgically treated group included 4,015 men with a median age of 62. Within this group, 2,643 men were treated. with surgery alone, and 1,372 men with surgery plus external beam radiation later.
After a median follow-up of 5.8 years (brachytherapy) and 6.4 years (surgery), the study team Reported 2014 that there was no difference in the speed of secondary malignancies between the groups, or within the incidence of cancer in the final population.
But not: In April 2024, researchers published Updated results. This time, the speed of latest cancers within the pelvis — including the bladder and rectum — was higher within the brachytherapy group. Specifically, 6.4 percent of men treated with brachytherapy developed a secondary malignancy during 15 years of follow-up, increasing to 9.8 percent after 20 years. In contrast, 3.2% and 4.2% of surgically treated men developed secondary pelvic dysfunction through the same period. There was no difference in mortality from secondary malignancies between the groups.
The strength of the association with bladder cancer specifically “is similar to that seen with smoking,” wrote the creator. Editorial. The authors concluded that “the results of the study should be considered when treating men with localized prostate cancer who have a long life expectancy.”
Expert opinion
“These malignancies usually occur in adjacent organs such as the bladder and rectum, or within the prostate itself. They can be highly curable, and thus have similar survival rates for patients treated with radiation or surgery. , but no doubt, for these patients, they represent a 'sting in the tail' after a long period of radiation being given and forgotten. offer life expectancy decades earlier, and it reminds us of the value of follow-up visits.”