Cancer Treatment Today » Brachytherapy

Plaque radiotherapy (brachytherapy) for choroidal melanoma – pro

M Levin, MD — Mon, 10 Sep 2012 20:07:56 +0000

Plaque radiotherapy is a different procedure than photocoagulation. Plaque brachytherapy is a widely accepted alternative to enucleation for medium-sized posterior uveal melanomas (<10 mm in height and <15 mm in diameter). The most common material used in modern plaques is iodine 125, because of its lower energy emission (lack of alpha and beta rays), its good tissue penetration, and its commercial availability. Radiation from this source causes tumor destruction through damage of DNA in cancerous cells and tumor vessels, with consequent tumor necrosis and regression. However, it is not devoid of complications. Plaque brachytherapy can cause complications, including cataract, rubeosis, scleral necrosis, keratopathy, radiation retinopathy, and optic neuropathy, but at a reduced rate compared with external beam irradiation.

Usually 10 mm or smaller is the appropriate sze of melanomas for this procedure. However, the American Brachytherapy Society’s guidelines state: “..some patients with large melanomas (>10 mm height or >16 mm basal diameter) may also be candidates.”

Previous publications have found several tumor features to correlate with increased mortality, including larger size, anterior location, transscleral extension, growth through the Bruch membrane, optic nerve extension, lack of pigmentation, and histologic characteristics (eg, mitotic activity and cell type). Although metastases from the primary intraocular melanoma can first be detected years later, their highest incidence is in the first year after diagnosis. There are no studies showing effectiveness of any kind of followup. As yet, no effective treatment exists for metastatic uveal melanoma and it is not certain that eraly diagnosis affects ultimate prognosis. As such, surveillacne cannot be recommended.

Eye plaques are individually designed and constructed for each patient. The precise distribution of radiation throughout the eye is calculated and used to determine the risks of secondary radiation complications. Because there si potential radiation exposure to others, laws regulate length of stay. Depending on the radiation laws of the state in which treatment is given, a patient may be required to stay in the hospital for the entire length of treatment(around 5 days). In any case, it is reasonable precaution.

REFERENCES:
Boldt HC, Melia BM, Liu JC, Reynolds SM; Collaborative Ocular Melanoma Study Group.
I-125 brachytherapy for choroidal melanoma photographic and angiographic abnormalities: the Collaborative Ocular Melanoma Study: COMS Report No. 30.Ophthalmology. 2009 Jan;116(1):106-115.e1.

Thomas Riley O.D. et al, Treatment options for choroidal malignant melanoma: a case report featuring transpupillary thermotherapy Optometry – Journal of the American Optometric Association
Volume 75, Issue 2, February 2004, Pages 103-114

http://www.cancer.org.au/File/HealthProfessionals/ManagementofOcularmelanomasupplementarydocument2008.pdf

American Brachytherapy Society recommendations for brachytherapy of uveal melanomas.Int J Radiat Oncol Biol Phys. 2003 Jun 1;56(2):544-55. .

I-125 brachytherapy for choroidal melanoma photographic and angiographic abnormalities: the Collaborative Ocular Melanoma Study: COMS Report No. 30.Boldt HC, Melia BM, Liu JC, Reynolds SM; Collaborative Ocular Melanoma Study Group.Ophthalmology. 2009 Jan;116(1):106-115.

Electronic radiotherapy – pro

M Levin, MD — Mon, 27 Aug 2012 15:59:57 +0000

The Axxent® Electronic Brachytherapy System® utilizes a miniaturized high dose rate X-ray source to apply radiation directly to the cancerous tumor bed. It was cleared for marketing by the FDA in December 2005. Unlike traditional high dose rate brachytherapy technologies, this form of brachytherapy is claimed not to require radioactive isotopes, heavy shielding, or major capital equipment. A number of posters and presentations, most of it in breast cancer, presented this new technology over the past three years. Five research studies were accepted for presentation at the 2008 World Congress of Brachytherapy hosted by the American Brachytherapy Society (ABS). One of them was about the use of the Axxent System for treatment of cervical cancer, subsequently published, and another about endometrial cancer.

Dickler A, Kirk MC, Griem K, Dowlatshahi K, Francescatti D, Abrams RA. A dosimetric comparison of MammoSite high-dose-rate brachytherapy and Xoft Axxent electronic brachytherapy. Brachytherapy 2007;6:164-168.

K. Huber, J. Hiatt, M. Puthawala, D. Wazer Dose modeling of the Xoft electronic brachytherapy source for tandem and ovoid applications in patients with cervical cancer
Brachytherapy, Volume 7, Issue 2, Pages 155-155

TEC, Accelerated Partial Breast Irradiation as Sole Radiotherapy After Breast-Conserving Surgery for Early Stage Breast Cancer
Assessment Program Volume 22, No. 4 September 2007

Brachytherapy for Prostate Cancer – pro

M Levin, MD — Thu, 16 Aug 2012 20:14:27 +0000

Prostate brachytherapy is among several roughly comparable options for front line treatment of localized prostate cancer available at this time. Unfortunately, there had not been a comparative prospective trial comparing seed implants, brachytherapy, external radiation, robotic prostatectomy, nerve sparing prostatectomy or conventional prostatectomy, proton beam radiotherapy and hormonal manipulation. Retrospective reviews, however, show these options to be similarly effective. A 2008 research summary by the Agency for Healthcare Research and Quality (AHRQ) noted that no randomized controlled trials had compared brachytherapy with other major treatment options for clinically localized prostate cancer. Currently, brachytherapy is widely used but with external beam radiotherapy( EBRT) support. The reason for it is that brachytherapy delivers radiation over very small distances. It does not, for example, get enough radiation to the outer part of the prostate. EBRT treats the areas in which radation distribution from brachytherapy is decreased. High dose approaches and combnations with other treatments may do what ERBT currently does. Whether some patients can avoid EBRT is being investigated.

Agency for Healthcare Research and Quality. Comparative Effectiveness of Therapies for Clinically Localized Prostate Cancer. AHRQ: Agency for Healthcare Research and Quality. Available at http://effectivehealthcare.ahrq.gov/healthInfo.cfm?infotype=rr&ProcessID=9&DocID=79. Accessed January 15, 2009.

Frank SJ, Grimm PD, Sylvester JE, Merrick GS, Davis BJ, Zietman A, et al. Interstitial implant alone or in combination with external beam radiation therapy for intermediate-risk prostate cancer: a survey of practice patterns in the United States. Brachytherapy. Jan-Mar 2007;6(1):2-8.

Grimm P, Billiet I, Bostwick D, Dicker AP, Frank S, Immerzeel J, et al. Comparative analysis of prostate-specific antigen free survival outcomes for patients with low, intermediate and high risk prostate cancer treatment by radical therapy. Results from the Prostate Cancer Results Study Group. BJU Int. Feb 2012;109 Suppl 1:22-9. [Medline].

Wattson DA, Chen MH, Moul JW, Moran BJ, Dosoretz DE, Robertson CN, et al. The Number of High-Risk Factors and the Risk of Prostate Cancer-Specific Mortality After Brachytherapy: Implications for Treatment Selection. Int J Radiat Oncol Biol Phys. Jan 31 2012;[Medline].

Yamada Y, Rogers L, Demanes DJ, Morton G, Prestidge BR, Pouliot J, et al. American Brachytherapy Society consensus guidelines for high-dose-rate prostate brachytherapy. Brachytherapy. Jan-Feb 2012;11(1):20-32.

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