Brachytherapy, prostate cancer

The two commonly used methods for radiation therapy are external-beam radiotherapy and brachytherapy.26 In external-beam radiotherapy, doses of 70 to 75 Gy are delivered in 35 to 41 fractions in patient with low-grade prostate cancer and 75 to 80 Gy for those with intermediate- or high-grade prostate cancer. Brachytherapy involves the permanent implantation of radioactive beads of 145 Gy of 125I or 124 Gy of 103Pd and generally is reserved for individuals with low-risk cancers. 

Pd103 17d Permanent implant brachytherapy for early-stage prostate cancer... 

Gomez-Iturriaga PA, Crook J, Borg J, Lockwood G, Fleshner N. Median 5 year follow-up of 125iodine brachytherapy as monotherapy in men agedprostate cancer. Urology 2010 75(6) 1412-6. 

This chapter presents a binary manipulator for MRI guided prostate cancer biopsies and brachytherapies using a transperineal approach (Figure 22.2). The problem of prostate cancer detection and treatment is exposed along with a review of alternative approaches. The proposed manipulator concept is presented and an analytical model of its performance is developed. Model predictions are compared with experimental data. Results show that... 

Figure 22.4 Prostate cancer transperineal brachytherapy treatment (The Prostate Cancer Centre, www.prostatecancercentre.co.uk).

Transperineal brachytherapy is growing in popularity over other treatment options because of a significantly smaller chance of incontinence and impotence, quick treatment and recovery and high success rates [15]. As brachytherapy becomes the method of choice, the procedure must become more reliable. Early detection through accurate biopsy needle placement is crucial to treat prostate cancer. To increase prostate cancer survival rates, it follows that needle placement methods must be improved with MRI guided methods. 

G., Kooy, H. M., and Coleman, C. N. (1998). Real-time magnetic resonance image-guided interstitial brachytherapy in the treatment of select patients with chnically localized prostate cancer, Int. J. Radial. Oncol. Biol. Phys. 42, 507-515. 

In another type of treatment for prostate cancer, long needles containing iridium-192 are placed in the tumor. However, the needles are removed after 5 to 10 min, depending on the activity of the iridium isotope. Compared to permanent brachytherapy, temporary brachytherapy can deliver a higher dose of radiation over a shorter time. The procedure may be repeated in a few days. 

Observational studies Acute urinary retention (AUR) is a severe acute toxicity of I brachytherapy for prostate cancer. To predict AUR prior to therapy and enhance individualised decision-making, a previously developed nomogram (assessing prostate volume, international prostate symptom score, neo-adjuvant hormonal treatment and prostate protrusion) was developed [32 ]. Validation of the nomogram was conducted in 715 patients treated with brachytherapy in which 9.4% developed AUR. Nomogram discrimination (ability to distinguish between patients who develop AUR yes or no) was adequate but calibration (agreement between observed and predicted numbers of AUR) was weak [33 ]. 

In the first phase I study, ten patients with recurrent prostate cancer underwent hyperthermia sessions alone, whereas in the second phase I trial eight patients also with recurrent prostate cancer were treated combining hyperthermia and low dose brachytherapy. Intraprostatic median temperatures measured in 90% of the cases (T90) were 40.1 °C for hyperthermia alone and 39.9 °C for the combined study. Differences between the planned and actual spatial distribution of the nanoparticles after injection were reported for those patients previously irradiated patients. Regarding adverse side effects, there is a temporal impairing of patients quality of life and local discomfort has been observed for field intensities over 4-5 kAm The potential efficacy of the proposed therapy was based on the decrease of the serum prostate-specific antigen in both groups of patients. 

Radiotherapy is a local treatment aiming to achieve local control or cure of locally confined tumours. It cannot treat metastases. Radiotherapy may be administered as external beam radiotherapy with X-rays or gamma rays, in sealed radioactive sources (e.g. prostate brachytherapy), or unsealed sources (e.g. orally administered radioiodine for thyroid cancer, intravenous strontium-89 for bone metastases). In external beam radiotherapy, the X-ray or gamma ray beams are targeted at the tumour to damage and kill the tumour cells. Inevitably, surrounding normal tissues are also affected resulting in the early and late side effects of radiotherapy. 

Another isotope, however, is beneficial for treating cancer, especially of the prostate. Cesium 131 has a half-life of only 10 days and emits low-energy photons that can be used to destroy cancer cells. Injection of a small source or"seed"of the radioisotope to a specific site—a process called brachytherapy—allows radiation to be aimed like bullets that can damage target receptor cells. It is especially potent against those that divide rapidly like cancer cells. 

Brachytherapy utilizes a solid source of radiation in the form of ingested seeds, ribbons, or capsules and allows for the administration of a higher dose of radiation to a smaller area of the body. Cancers of the head, neck, breast, uterus, cervix, prostate, gall bladder, esophagus, eye, and lung are often treated with brachytherapy. Liquid forms of internal radiation are most often used with people who have thyroid cancer or non-Hodgkin s lymphoma. Internal radiation therapy may be combined with external beam radiation, chemotherapy, or surgery. 

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