Consultation/Patient Selection
The prostate brachytherapy process begins with a consultation, during which the radiation oncologist will review all of a patient’s relevant medical records, interview and examine him, and render an initial opinion as to whether prostate brachytherapy or one of the other forms of prostate radiotherapy is a good treatment option. Every patient has a choice of radiotherapy treatment options, and each of these options is addressed during the consultation process.
There may be aspects of an individual patient’s case that cause the radiation oncologist to specifically recommend either brachytherapy or a different radiotherapy option as the “best” or “preferred” prostate cancer treatment for that case. In other cases a patient be equally well treated by any of several radiation therapy methods and in these cases, our radiation oncologist simply tries to give the patient a full overview of the potential benefit and risk of every radiotherapy treatment option, leaving the final decision as to which option to the patient himself. Some patients may be sure of their choice immediately, while others may find the decision making process very difficult. Patients are encouraged to take their time, research all treatment options, talk to other physicians and family members, so they may make their best treatment selection.
Patients who are good permanent source prostate brachytherapy candidates have clinically localized disease, meaning that their cancer is contained within or very near the prostate. Patients with the highest probability of satisfying this condition are those with a tumor stage (T-stage) of T1 or T2a-b (FIGURE 1), prostate-specific antigen (PSA) level less than or equal to 10ng/ml, and Gleason Score less than or equal to 6 (FIGURE 2). We normally refer to these patients as “favorable” prognosis patients.
Patients with a higher PSA or Gleason score may still be reasonable permanent seed prostate brachytherapy candidates, but will not have a cure rate as high, because they have a higher chance of cancer cells that have spread beyond the prostate, beyond the radiation volume produced by the brachytherapy seeds. This same trend to decreased cure rate in these patients with a higher PSA level or Gleason score is seen with all methods of treatment.
Depending on their exact situation, these patients may be referred to an “intermediate” prognosis or “unfavorable” prognosis patients. We have successfully implanted a number of these patients, using extra-prostatic stranded source placement (FIGURE 3) (FIGURE 4), in areas judged to be at increased risk of extra-prostatic cancer cell extension. The appropriateness of this treatment method is determined on a case-by-case basis by the radiation oncologist and patient.
Patients with locally advanced cancers (Large T2b, T3) or other “unfavorable” prostate cancers may be better treated with IMRT (FIGURE 5)or HDR brachytherapy plus 3D conformal external beam radiation therapy (FIGURE 6). Please refer to those sections for further information. No matter what type of radiation or surgical treatment is administered for prostate cancer, the probability of success will be the highest in “favorable” patients, intermediate in “intermediate” patients and lowest in “unfavorable” patients.
In addition to the cancer factors discussed above, an equally important permanent seed brachytherapy patient selection criterion is their lower urinary tract function. Permanent seed prostate brachytherapy produces prostate swelling and inflammation. In some patients this will translate to a higher chance of total urinary obstruction, which means inability to void, which may be brief or may be long lasting and miserable, though with eventual resolution in a majority of cases.
In our experience, the response to the AUA form (FIGURE 7)has most accurately predicted which patients are at higher risk of long-term urinary obstruction following their prostate brachytherapy procedure. If a patient has a high AUA score or other evidence of urinary obstruction, he may be advised to take other than brachytherapy, though again, these decisions are carefully made on a case-by-case basis. Sometimes medical or surgical corrective measures may be done to improve this situation prior to the implant, causing the patient to be able to better tolerate the procedure.
Other risk factors for urinary obstruction or complications following prostate brachytherapy may include prior pelvic radiation, hormonal therapy, large prostate volume, or a history of prior prostate surgery. If a patient has any of these factors it may or may not still be appropriate to perform brachytherapy, subject to case-by-case evaluation.
A large prostate volume in the absence of other risk factors has not been a serious risk factor for long-term problems after the procedure in our patients, though these patients have tended to have more trouble with urinary obstruction during the first several weeks after the procedure, due to the swelling of their (already large) prostate. This appears to be related to needle trauma, because larger prostates require a larger number of needle punctures, to deliver a larger number of seeds. This reaction normally settles after several weeks, after which our large prostate patients appear no different from the rest of the brachytherapy population in their side effect profile.
In summary, the ideal prostate brachytherapy candidate has a reasonable expectation of cancer confined to the prostatic region, and also has adequate lower urinary tract function to accommodate the side effects of the brachytherapy procedure.
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3D Conformal Radiotherapy (with IMRT)
High Dose Rate Prostate Brachytherapy
CyberKnife Radiosurgery
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