Beam radiation has long been a mainstay in the arsenal of weapons against prostate cancer (PCa). Over 50 years ago, when more powerful radiation equipment allowed deeper penetration into the body, patients who could not have surgery began to be treated with “megavoltage radiation”. The past three decades have seen advances in the ability to deliver 3D conformal beam radiation, intensity modulated radiation therapy, and proton beam radiation—all improvements in focusing the radiation dose in order to be more effective against the cancer while doing less damage to nearby structures.
Radiation functions very differently than ablation (destruction) of tumors with thermal energy. Perhaps the biggest difference is that radiation, unlike extremes of heat or cold, does not kill cancer all at once. Cancer cells, which are more susceptible to radiation, fail to reproduce over time because the constant exposure to radiation damages the cells’ DNA. The most important fact is that the exposure has to occur over a reasonably long period. This is why patients undergoing beam radiation have to come 5 days a week for 4-5 weeks for short bursts of exposure; and it’s why radioactive seed implants (brachytherapy) are placed in the gland and left there for the rest of the patient’s life as the radiation gradually diminishes. The duration of exposure to radiation scatter is also a reason why radiation patients have a greater chance of eventually developing secondary cancers such as rectal or bladder cancer.
Even with technologic improvements, ALL radiation has some scatter effect and ALL radiation will have more or less of an impact on healthy tissue. This results in a higher rate of cumulative damage leading to side effects than radical prostatectomy (RP). In fact, a new study presented at the 70th annual Canadian Urological Association meeting (Ottawa, Canada, June 27-30) cited side effect statistics in comparison with RP.[i] Dr. Christopher Wallis and colleagues from the University of Toronto shared findings based on analysis of data from the SEER Medicare registry. They had access to records of 60,476 men aged 65-79 years who either had RP or radiation therapy (beam or seeds). After adjusting for differences, the team discovered the following:
|RP (14,492 men)||Radiation (60,476 men)|
|Slightly higher rate of major surgical procedures for complications||25% greater risk of post-treatment minimally invasive urologic procedures for complications|
|40% greater risk of rectal/anal procedures|
|80% greater risk of hospital admissions after treatment|
For both treatments, the complication rates reached their highest point within two years after treatment, but in both complications continued at a steady rate for the next 10 years. Until something better comes along, radiation will have a place for those who can’t have or don’t want surgery. Even so, patients considering radiation deserve transparent discussions of the risks they face.