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Treatment of Prostate Cancer: Radioactive Seed Implantation

(Brachytherapy)

Duke K. Bahn, M.D.

Department of Radiology, Crittenton Hospital, Rochester, MI

(248) 652-5611

Editors Note:I feel it is appropriate to state that Dr Bahn is both a colleague and professional associate of mine.

Introduction

Brachytherapy is a form of radiation treatment in which tiny pellets containing radioactive material, such as Iodine-125, are implanted directly into the tumor containing organ. This form of radiation therapy has long been used in other types of malignancies including cervical, breast, endometrial as well as head and neck cancers. Brachytherapy offers the appealing concept of delivering high doses of radiation to the prostate while limiting the exposure to the adjacent organs.

History

Brachytherapy of the prostate goes back to 1911 when Pasteau published the first case in medical literature. Utilizing a technique, which is rather crude by today's standards, Pasteau simply used a catheter to insert radium into the prostatic urethra. Although the results showed fairly good local control of the cancer, the complications were too high to be considered acceptable. Dr. Whitmore introduced an open-surgical, retro-pubic brachytherapy method in 1972, using Iodine-125. This method did not gain wide acceptance due to less than satisfactory clinical results and various complications.

These early failures, to a large degree, were due to the fact that they were performed utilizing "blind" approaches. The imaging technologies, crucial for seed implantation, were not yet available. Some researchers tried temporary implantation with iridium-192 using an open surgical field, but they were still unable to visualize the internal structures of the gland. This technique was also burdened by the limitations of a blind approach. Precise placement of seeds a crucial factor in the success of brachytherapy. Without the benefit of modern day imaging techniques accurate placement of the radioactive seeds was not attainable

In the early 1980s, the old concept of brachytherapy was revisited. Improved imaging technologies made the procedure more feasible. The most important of these were transrectal ultrasound (TRUS) and computerized tomography (CT). These new technologies allowed a non-surgical, uniform seed distribution into the prostate through needle punctures. With the most recent developments in computer software, TRUS has become the most commonly used modality for seed implantation procedures. However, the results can be highly operator-dependent.

Candidates for Brachytherapy (seed implant) at Crittenton Prostate Center:

In determining who is a candidate for seed-implant therapy, there are several factors which must be considered. The patient's general state of health is a very important factor in determining which form of therapy should be chosen. Since this procedure is only minimally invasive, it is better tolerated than the more aggressive surgical procedures. The age of the patient is also important for this same reason. Therefore, an older patient that requires treatment, may consider brachytherapy as an option.

Accurate staging of the tumor is also mandatory before considering brachytherapy. Patients with early-stage, small-volume tumors are the best candidates for this procedure. Treatment with implants alone( either iodine- 125 or palladium -103 ) is usually adequate for an early stage small volume prostate cancer. For larger volume tumors, brachytherapy is usually performed in combination with external-beam radiation.

Younger patients, with early small volume tumors, may also chose brachytherapy because of the lower complication rates. This is especially true when impotency is a major consideration. Nevertheless, concerns over impotency should not allow the tumor treatment to be compromised. There are newer drug therapies which will allow impotent men to maintain erections. The treatment decision is a highly personal one that involves both medical, personal and life-style issues. The most important first step is that the patient needs to have his tumor accurately staged. Under staging (under estimated) a cancer is the most common reason for patients choosing inappropriate treatment options. This often leads to subsequent treatment failures.

Iodine-125 seed Implant alone Criteria 1. Tumor stage : less than or equal to T2a 2. Gleason grade : less than or equal to 7 3. PSA : less than or equal to 10 4. If prostate volume is over 40 cc, pre-operative Androgen Ablation (Hormone) therapy for 3 - 6 months duration.

Palladium-103 seed Implant with External Beam Treatment Criteria 1. Tumor Stage : T2b, T2c, or T3a 2. Gleason grade : over 7 3. PSA : over 10, but less than 30 4. All patients get 3 - 6 months of Androgen Ablation Therapy 5. The gland volume after AAT must be less than 40 cc

Procedures before seed implant : 1. A precise prostate volume study, utilizing dedicated transrectal ultrasound, is performed to create a road map for seed implantation. This is usually done about 2 weeks before the treatment. A radiologist, who is specially trained in this field, will do the study in conjunction with a medical physicist and a radiation oncologist who will jointly determine the number of seeds needed and where they should be placed. 2. Routine pre-operative tests ( Blood test, EKG, chest X-ray etc.) will be done a few days before the treatment. Specific instructions will be given to you regarding diet and bowel prep. Procedures during seed implant : 1. Unless there are contraindications (factors preventing it) the procedure is performed in the operating room under spinal anesthesia. 2. An ultrasound probe is inserted into the rectum to image the prostate. The prostate is continuously visualized during the course of the procedure. 3. Based on the planning map, an average of 50 - 100 seeds are placed in the prostate through a needle which is placed through the perineum (skin between the rectum and the scrotum). The ultrasound guidance provides for precise and accurate positioning of the seeds. 4. At the end of the procedure, a catheter is temporarily inserted into the patient's bladder to assure the adequate drainage of urine. This entire seed placement procedure takes about one hour.

Procedure after implant : 1. The patient is transferred to a recovery room and remains there about two hours with an ice bag placed at the needle entry site in perineum. This is done to reduce the local swelling. The Foley catheter is removed after the anesthesia has worn off and the patient has regained urinary control. Occasionally, the catheter may be left in overnight. 2. The patient is usually discharged that same day. However, it is strongly recommended that he not drive himself home. There are no diet restrictions. Heavy lifting and/or strenuous exercise are prohibited for approximately two weeks.

Follow-Up Schedule

At our institution the patient is required to have a PSA test every 3 months for next 12 - 18 months after the procedure, followed by one every 6 months for five years. Biopsies should also be performed at 18 and 60 months after the procedure.

Radiation Safety

Potential dangers of radiation to the family members are almost non-existent. Iodine-125 emits very low energy radiation, which is mostly contained in the region of the prostate. However, small amount of radiation may escape from the prostate and travel a short distance. It is also possible for very small amounts of radiation to escape the body when a patient passes a radioactive pellet through the urine. For this reason, it might be prudent to avoid close contact small children or pregnant women during the first two months following implantation. The patient may also wear a protective brief to prevent radiation leakage entirely.

Clinical Outcome and Complications

Recent data, based on over 450 patients followed for up to six years, show a higher percentage of local control of the disease than that provided by either radical prostatectomy or external-beam radiation. The results are very similar to our cryotherapy statistics. However, it should be noted that the patient selection was more stringent in seed implant group. Seed implantation therapy is only offered to the selected group of patients who have small-volume, early-stage cancer.

Complication rates are generally lower in brachytherapy than with other modalities . Complications include : proctitis; cystitis; incontinence; rectal bleeding. Current literature reports that these occurs in less than 5 % of the patients. However, it is common to experience problems with urination for a few months after seed implantation. Various degrees of impotency are also common after the procedure. The reported impotency rates are in the 20 - 50 percent range. However, there is also a correlation with the patient's age and general state of health.

Conclusions

Prostate Cancer is an enigmatic disease. A generally agreed on single best treatment method is not known at this time. The traditional "gold standard" treatment has been radical prostatectomy or external beam radiation. Unfortunately, both these procedures suffer rather high failure and complication rates. There may not be a need for these invasive treatments for every prostate cancer. For some, these options may be an over treatment, needlessly exposing the patient to potential complications. In certain groups of patients, less invasive treatments, such as cryotherapy or brachytherapy, may prove adequate. Short-term clinical data indicate a fairly high rate of success, with significantly low complication rates, compared to the traditional treatments. Most patients maintain quality of life and also the cost of the treatment is significantly lower. It cannot be over stressed that the single most important factor in choosing an appropriate treatment is having the correct initial staging of the tumor.

As with cryotherapy, the brachytherapy procedure is highly operator-dependent. The equipment used is also important. Reputable, comprehensive prostate cancer centers should be able to offer all types of prostate cancer treatment including, watchful waiting, androgen ablation therapy, radical prostatectomy, cryotherapy, and external- and internal-beam radiation treatment (brachytherapy). The use of only state-of-the-art equipment is essential. It is prudent for every patient to investigate all of the treatment options thoroughly before making the treatment decision. Since the tumors are usually slow growing, the patient has time to educate himself and to investigate the treatment options.

Cancer News on the Net wishes to thank Dr Bahn for contributing this fine article to our service!!!

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