In the treatment of prostate cancer, ionising radiation can be delivered to the tumour either using external beam radiotherapy (EBRT) or by implanting radioactive seeds into the prostate (brachytherapy).
In EBRT, multiple doses of ionising radiation are delivered to the tumour from an external source over a period of several weeks on an outpatient basis.1,2 Ionising radiation must be delivered precisely to the prostate (and sometimes the lymph nodes) whilst avoiding irradiation of normal tissues.3 Modern EBRT techniques such as 3D conformal therapy (3D-CRT), intensity-modulated radiotherapy (IMRT), image-guided radiotherapy (IGRT) or tomotherapy use spatial information to secure accurate delivery of radiation to the tumour whist sparing healthy tissue,3,4 and so can significantly reduce side effects compared with traditional EBRT.5 Adverse events of 3D-CRT are generally mild-to-moderate and include incontinence (occurring less frequently than with radical prostatectomy6) and diarrhoea.7 In addition, hematuria, rectal bleeding, and erectile dysfunction may occur as a side effect of radiotherapy.4,7,8
In clinically localised prostate cancer, EBRT is recommended for older patients or younger patients who wish to avoid surgery.4 EBRT is also recommended for high-risk localised or locally advanced disease, where overall survival is moderated by combining EBRT with hormonal therapy.4
Seed implant or brachytherapy involves the direct implantation of radioactive sources into the prostate gland.9 In low-dose rate brachytherapy, seeds containing either iodine-125 or palladium-103 are placed permanently in the prostate via the transperineal route under transrectal ultrasonography guidance in a single outpatient visit.1,9 As with EBRT, the main side effects are urinary, gastrointestinal and sexual dysfunction.3 When brachytherapy is performed in well-selected patients (e.g. low-risk prostate cancer, small prostate, no urinary symptoms), functional recovery is extremely good10 and the procedure generally requires less than two days of hospitalisation.4 Brachytherapy is recommended for these patients4 and is an ideal treatment for men who wish to maintain their lifestyle during treatment for prostate cancer. Brachytherapy is not recommended for high-risk localised prostate cancer.2
More recently, high-dose rate brachytherapy has emerged as a new modality for localised prostate cancer. It involves the temporary transperineal implantation of hollow needles into the prostate gland, which deliver high intensity iridium radiation to the tumour.9
Referernces:
1. Wilt TJ, Thompson IM. Clinically localised prostate cancer. BMJ 2006;333:1102-6.
2. National Institute for Health and Clinical Excellence. Clinical guideline 58. Prostate cancer, February 2008.
3. Michaelson MD, Cotter SE, Gargollo PC, Zietman AL, Dahl DM, Smith MR. Management of complications of prostate cancer treatment. CA Cancer J Clin 2008;58:196-213.
4. European Association of Urology. Guidelines on prostate cancer, 2010.
5. Jani AB, Su A, Correa D, Gratzle J. Comparison of late gastrointestinal and genitourinary toxicity of prostate cancer patients undergoing intensity-modulated versus conventional radiotherapy using localized fields. Prostate Cancer Prostatic Dis 2007;10:82-6.
6. Chen RC, Clark JA, Talcott JA. Individualizing quality-of-life outcomes reporting: how localized prostate cancer treatments affect patients with different levels of baseline urinary, bowel, and sexual function. J Clin Oncol 2009;27:3916-22.
7. D'Amico AV, Manola J, Loffredo M, et al. 6-month androgen suppression plus radiation therapy vs radiation therapy alone for patients with clinically localized prostate cancer: a randomized controlled trial. JAMA 2004;292:821-7.
8. Potosky AL, Davis WW, Hoffman RM, et al. Five-year outcomes after prostatectomy or radiotherapy for prostate cancer: the prostate cancer outcomes study. J Natl Cancer Inst 2004;96:1358-67.
9. Kirby RS, Patel MI. Fast facts: prostate cancer (5th ed). Health Press Ltd: Oxford, 2008.
10. Ash D, Flynn A, Battermann J, et al. ESTRO/EAU/EORTC recommendations on permanent seed implantation for localized prostate cancer. Radiother Oncol 2000;57:315-21.