Permanent Prostate Brachytherapy

Per­ma­nent prostate brachyther­a­py (seed implant) is a prostate can­cer treat­ment that uses ion­iz­ing radi­a­tion to destroy can­cer cells. The radioac­tive mate­r­i­al is placed either direct­ly into a malig­nant tumor or very close to it, thus the term brachyther­a­py, which means short ther­a­py in Greek. Radi­a­tion kills the tumor by destroy­ing the DNA with­in the can­cer cell. When the can­cer cell attempts to divide and repro­duce itself, it is unable to do so because the DNA is no longer intact and as a result, the prostate can­cer dies.

In 1916, the first prostate brachyther­a­py pro­ce­dure was per­formed. Over the past twen­ty years, tech­nol­o­gy has result­ed in dra­mat­ic advance­ments of prostate brachyther­a­py. Improved ultra­sound equip­ment used to visu­al­ize the prostate and pre­cise­ly guide the place­ment of radioac­tive seeds allows for the deliv­ery of a very high dose of radi­a­tion to the prostate, while min­i­miz­ing the dose to the sur­round­ing nor­mal body organs such as the blad­der and rec­tum. As a result, prostate brachyther­a­py has become very pop­u­lar as a treat­ment option for patients diag­nosed with ear­ly-stage prostate cancer.

What is involved with prostate can­cer treatment?

Ultra­sound images (vol­ume study) allow a physi­cian to deter­mine the exact shape and size of the prostate gland. Out­lin­ing the area of the prostate gland where the can­cer was iden­ti­fied on biop­sy also assists physi­cians in treat­ment planning.

These pic­tures are then recon­struct­ed on a three-dimen­sion­al treat­ment plan­ning com­put­er and allow the physi­cian to deter­mine exact­ly how many seeds are need­ed and where they should be placed with­in the prostate gland and in rela­tion to the ure­thra, blad­der, and rectum.

The treat­ment plan for prostate cancer

Each seed implant is indi­vid­u­al­ly planned to deter­mine the opti­mal dis­tri­b­u­tion of radi­a­tion. The radi­a­tion oncol­o­gist and a team of med­ical physi­cists are spe­cial­ly trained to under­stand the best dose of radi­a­tion to give to the prostate while also pro­tect­ing the rec­tum and blad­der from radi­a­tion. A per­ma­nent prostate seed implant is per­formed using cesium (cs131), iodine (i125) or pal­la­di­um (pd103) in the form of small radioac­tive seeds.

Since they are locat­ed close to or with­in the can­cer, the radioac­tive seeds can deliv­er a sig­nif­i­cant amount of radi­a­tion in an area no larg­er than a cen­time­ter, while the adja­cent area receives min­i­mal, if any, radi­a­tion. A physi­cian can there­fore implant high dos­es of radi­a­tion into the prostate while avoid­ing nor­mal crit­i­cal struc­tures such as the blad­der and rectum.

When is brachyther­a­py appropriate?

Typ­i­cal­ly, the best can­di­date for brachyther­a­py is some­one with a prostate tumor con­fined to the prostate gland that has a very low risk of spread­ing to oth­er parts of the body. This is referred to as monother­a­py (or one treatment). 

Brachyther­a­py is also the pre­ferred treat­ment for those with inter­me­di­ate or high-risk prostate can­cer. The seed implant is often per­formed in com­bi­na­tion with exter­nal beam radi­a­tion ther­a­py, plus or minus hor­mone ther­a­py. This is referred to as com­bi­na­tion ther­a­py. Your physi­cian will help guide you towards the most appro­pri­ate treat­ment plan.

Brachyther­a­py is not appro­pri­ate in patients whose can­cer has already spread beyond the prostate and into oth­er areas of the body. Patients who have had a transurethral resec­tion of the prostate (turp) may have brachyther­a­py, how­ev­er, they will need to meet cer­tain criteria.

How much radi­a­tion will I receive?

The total amount of radi­a­tion the prostate gland will receive depends upon the amount of radi­a­tion in each seed and the total num­ber of seeds deposit­ed. A typ­i­cal implant usu­al­ly requires approx­i­mate­ly 60 to 100 seeds, depend­ing on the size and shape of a patient’s prostate gland. The extent of treat­ment that a patient requires is depen­dent upon the risk that his can­cer is con­fined to the prostate. As a rule, low-risk patients require one treat­ment, such as per­ma­nent seed implant. Hor­mone ther­a­py in this group of patients may be used to reduce the over­all size of a large prostate gland.

It is often rec­om­mend­ed that men at inter­me­di­ate risk for can­cer that has spread under­go more aggres­sive treat­ment. At a min­i­mum, this means a com­bi­na­tion of hor­mone ther­a­py plus a seed implant. In some cas­es, even more aggres­sive mea­sures, such as adding five weeks of exter­nal beam radi­a­tion ther­a­py (EBRT) to a seed implant, may be indi­cat­ed. The pur­pose of the addi­tion­al EBRT is to kill any can­cer cells that may have escaped the prostate and are in the tis­sue around the prostate. High-risk patients can also ben­e­fit from brachyther­a­py, but this is usu­al­ly done in com­bi­na­tion with EBRT and hor­mone therapy.