Brachytherapy

It involves the targeted use of high energy light or particles to kill cancer.

Radioactive implants utilized to deliver greater doses of radiation to a tumor than to healthy surrounding tissues.

Radioactive sources are directly placed into or next to the tumor to be treated, either directly or by means of catheters.

The placement of radioactive sources is often called an implant.

Very high doses of radiation are delivered from  the inside out, killing cancer cells and decreasing the risk of damage to nearby organs.

Dose of radiation decrease as inverse square of distance from the source.

Its efficacy relies on the high radiation dose delivered directly to the tumor, close to the sources.

The specificity is that there is a rapid dose fall-off a distance from the sources, limiting dose exposure of surrounding tissues.

It offers dosimetric advantages with very sharp radiation dose gradients compared with conventional external beam techniques.

It combines optimal tumor to normal tissue gradients while minimizing the integral does to the rest of the patient.

It is indicated in three major situations: as curative definitive radiotherapy with or without chemotherapy, as adjunctive treatment to decrease the probability of local relapse after surgery and has palliative treatment of symptomatic metastases.

Brachytherapy is indicated as an exclusive treatment or combined  with other treatment modalities such as external radio therapy or surgery.

Used for cervical cancer, prostate cancer and other lesions that can be accessed with minimally invasive procedures.

Brachytherapy is appropriate as mine or therapy to treat small tumors accessible for implantation using visual, manual, or radio logical guidance.

This technique is optimal for conserving treatments and avoiding mutilating surgery without jeopardizing the probability of cure.

Has been used to treat prostate, cervical, uterine, skin, eye and breast cancers.

Source placement can be temporary or permanent.

Permanent placement such as with radioactive seeds are placed during a single procedure and left inside of the body.

Permanent seeds lose their energy over time and essentially become inactive after a few weeks.

With temporary placement hollow catheters are placed into the tumor, allowing radioactive sources to temporarily enter the body, and then are removed after the procedure.

Temporary implants may be spread out over multiple treatments to decrease the risk of adverse effects.

The total dose can be delivered through a continuous load dose rate irradiation, a low intensity pause repeated every hour up to a few days, or a few fractions delivering high doses each time.

Various radioisotopes are used, the most commonly are iridium-192, cobalt-60, Iodine-125, and palladium-103.

Treatment delivered as a low dose rate therapy in which 1 Gy per hour administered by radioactive sources that are left permanently or removed after a day or so, or can deliver high dose rate treatment during which radiation is delivered over minutes and typically separated by days to weeks.

Brachytherapy can be used alone or in combination with external beam radiation therapy.

Its main limitation is its invasive procedure, requiring an operating room to place resources or the catheters.

The quality of implantation is an important dynamic of the therapeutic index.

Any inappropriate positioning of sources may expose tumor to underdosing or the patient’s tissues to receive excessive toxicity.

Prostate cancer risk stratification systems are based on the premise that serum PSA, clinical T stage and Gleason score are independent predictors of biochemical failure free survival.

Localized prostate cancer patients with low risk features can be treated with brachytherapy has 5 year PSA failure outcomes that are similar compared with radical prostatectomy and external beam radiation.

For prostate cancer complications include 38% of patients ultimately require 1 or more physician visits secondary to urinary retention, hematuria, infection, dysuria or rectal bleeding.

For men age 65 years at diagnosis followed with active surveillance received an additional six months of quality-adjusted life expectancy compared with treatment with brachytherapy (Hayes JH et al).

The Expanded Prostate Cancer Index Composite quality of life instrument showed that brachytherapy and external being radiation have better preservation of erectile function and urinary continents than does surgery.

The Expanded Prostate Cancer Index Composite quality of life instrument demonstrated lower rates of rectal irritation than did external being radiation, but had higher rates then surgery did.

The Expanded Prostate Cancer Index Composite quality of life instrument Indicated brachytherapy had higher rates of urinary obstructive symptoms than did either external being irradiation or surgery.

Patients who have enlarged prostate glands or marked obstructive voiding symptoms at baseline are not good candidates for brachytherapy.

8-10% of patients have temporary urinary retention during the first couple of weeks following brachytherapy therapy.

For prostate cancer complications include obstruction requiring urinary catheter in approximately 5-32% of patients.

For prostate cancer a large prostate is a relative contraindication due to technical problems and the perception of higher risk for acute and prolonged urinary morbidity.

In patients with prostate volume >50 cm3 neoadjuvant therapy for cytoreduction is usually given.

For prostate cancer associated with increased urinary morbidity with transition zone volume.

For prostate cancer it is noted that periprostatic radiation coverage maximizes the likelihood of eradicating early stage prostate cancer and requires that seed coverage be placed to achieve 3-5 mm periprostatic coverage by placing seeds on or slightly outside the prostatic capsule.

In treating high risk disease modern technique allow for generous extra capsular margins and treatment of the proximal seminal vesicles, with added benefit of intraprostatic dose escalation.

For prostate cancer with contemporary evaluations reveal excellent biochemical control rates among individuals with imtermediate and high risk disease.

For prostate cancer it has been established that extraprostatic extension of disease ranges from 0.5-2.4 mm and the radial extent of such disease in nearly 99% of cases is limited to equal or less than 5mm (Davis).

For prostate cancer has revealed that the average postimplant treatment margins of 3-6 mm at the 100% isodense line indicating that such treatment provides margins that should be sufficient to eradicate extraprostatic disease (Merrick).

In prostate cancer the D90, referring to the maximum dose covering 90% of the prostatic volume, and the V100, referring to the percentage of the prostatic volume covered by the dose, have a major impact on biochemical control rates.

In prostate cancer median time to resolution of spectroscopic abnormalities as assessed by endorectal magnetic resonance imaging and spectroscopy is 32.2 months, compared to 24.8 months with permanent prostate seed implantation (Pickett).

Prostate brachytherapy has a faster recovery time than radical surgery and a shorter duration of treatment compared to external beam radiation.

For prostate cancer has a greater degree of atrophy and magnitude of the decline in PSA levels after brachytherapy for prostate cancer than after external beam radiotherapy

Prostate brachytherapy an application to men with a median age of 70 years.

Vast majority of patients treated for prostate cancer have obstructive symptoms after treatment and in most the symptoms resolve after several months.

Rates of obstruction after prostate brachytherapy for prostate cancer requiring TURP or dilation 5-15%.

For prostate cancer complications include urinary retention (6%), incontinence (12-18%), cystitis (4-7%), proctitis (1-16%), and impotence (44-79%).

The Prostate Cancer Outcomes and Satisfaction with Treatment Quality assessment (PROST-QA) study revealed that patients treated with surgery or brachytherapy had acute decrements in their quality of life and by 2 years surgical patients had worse outcomes for sexual function and urinary incontinence, while brachytherapy patients had worse urinary obstruction or irritation problems and more problems with their rectum and bowels (Sanda MG).

No difference in radiation induced second primary cancers between prostate cancer treated with prostatectomy or brachytherapy, with no increase in tumor incidence compared with the general population (Hinnen KA et al).

Prostate brachytherapy with I-125 associated with a slight increase in bladder cancer risk (Henry A et al).

For uterine cancer brachytherapy application consist of inserting a plastic tube within the uterine cavity and an applicator within the vaginal cavity.

This insertion requires anesthesia and dilatation of the cervical canal.

Breast cancer treatment can be perioperative for postoperative consists of placing radiation sources within the tumor bed to decrease the risk of local relapse by delivering focused radiation to treat only lumpectomy bed plus a safety margin after breast conserving surgery.

Brachytherapy has been affected for treating penile glans cancer, pediatric rhabdomyosarcoma, anal cancer, and varying head and neck cancers

Adverse effects of brachytherapy related to the location of treatment: patients with cervical cancer may have burning upon urination with diarrhea, patients with skin cancer may have sunburn type reaction.

Adverse effects generally subside within one month of treatment.