20 Prostate Cancer

Prostate Cancer

6

THE GEC ESTRO HANDBOOK OF BRACHYTHERAPY | Part II: Clinical Practice Version 1 - 01/12/2014

of measuring free and bound PSA ratios; an excess of free PSA over bound is more usually associated with malignancy. Uri- nary PCA3 (Prostate Cancer Gene 3) is a new test now available which is said to have greater specificity for prostate cancer than PSA; it may have a role in screening but for evaluation prior to brachytherapy there is no data to evaluate its role above PSA for selection and prediction of outcome. Diagnosis will usually be confirmed by transrectal ultrasound guided biopsies of the gland. Typically extensive sampling from all four sextants will be undertaken to ensure adequate sam- pling of the gland. However this may miss anterior sections of the gland. Increasingly image guided transperineal biopsy tech- niques are being used to target areas shown to be likely sites of tumour after imaging; these techniques also enable accurate mapping of the cancer throughout the gland. The biopsy samples should be examined by an experienced prostate pathologist; as a minimum the Gleason grade for each biopsy and the presence of perineural invasion should be reported. On transrectal ultrasound malignant tumours of the prostate cause usually hypoechogenity compared to normal prostate tis- sues. The normal prostate has a homogenous echoic structure but large tumours sometimes contain echogenic regions. The dimensions in young men are typically 45 mm in the transverse plane, 35 mm cranio-caudal and 30 mm dorso-ventral with a volume of 18-23 cc. Usually it is easy to define the prostatic part of the urethra, the muscles of the internal sphincter as well the periurethral stroma. They are less echogenic compared to the covering peripheral part of the prostate. In the sagittal planes the ejaculatory ducts and the ampullae of the vas deferens are also readily identified. Hyperplastic adenomas are located most frequently in the tran- sitional zone, seldom in the central zone – but almost never in the periphery of the prostate. On the other hand, 70-80% of ma- lignant tumours origin in the peripheral zone and later can infil- trate the surrounding areas. In regions with cancer involvement the zonal anatomy as well the borders of the prostate are less sharp and areas of cancer infiltration are visible as hypoechoic regions. Following histological confirmation of prostate cancer all pa- tients should have pelvic imaging to refine the clinical stage of the tumour and identify those with gross ECE or seminal vesicle invasion. MRI is vastly superior to CT for this and multi-para- metric MR including T1, T2, dynamic contract enhanced (DCE) and diffusion weighted (DWI) is now considered the gold stand- ard [6]. The role of an isotope bone scan in low risk patients is controversial; the likelihood of bone metastases when the PSA is below 10 and Gleason score is 7 or less is <1% and there is no justification for a bone scan; but as the PSA rises above 10 and in patients with a Gleason score of 8-10 an isotope bone scan should also be undertaken. Where the results of screening with isotope bone scan and MR are equivocal choline PET may have a role in evaluating metastatic disease but is of no value in staging the primary tumour. Conventionally prostate cancer is classified into three risk groups; low, intermediate and high. Several classifications have been described all using serum PSA, Gleason score and T stage. The D’Amico classification is the most widely accepted and shown below:

Low risk: PSA<20ng/ml Gleason 3+3=6 Stage T1, T2a or T2b Intermediate risk: One of the above criteria not met High risk: Two or more of the above criteria not met

6. INDICATIONS AND CONTRAINDICATIONS

6.1 Indications for brachytherapy Selection of patients for brachytherapy will be based upon a number of factors, taking into account the competing options for localised prostate cancer which include active surveillance, radical prostatectomy, external beam radiotherapy and minimal intervention techniques for focal disease using high frequency ultrasound (HIFU) or cryotherapy. In many situations where there is low risk disease the outcomes of treatment in terms of biochemical disease control and survival will be no different and the decision is therefore based on competing morbidities and pa- tient preference. In more advanced disease where prostatectomy is less likely to achieve complete surgical clearance and active surveillance is not indicated then the role of brachytherapy may be in combination with external beam radiotherapy to achieve dose escalation. The indications for the two different brachytherapy techniques, permanent LDR seed brachytherapy and temporary HDR after- loading brachytherapy are different and are discussed below: Permanent LDR seed brachytherapy The indications for LDR prostate brachytherapy have been de- scribed by several guidelines [7][8][9][10]. Patients should have a life expectancy of at least ten years, since in these patients it is not expected that they will die within this period of their pros- tate cancer. The disease should be localised within the prostate capsule, ie stage T1 and T2 and should have low risk factors for ECE according to the Partin tables [11] and there should be no evidence of metastases. The patient should be carefully clinical- ly assessed with regard to possible interference from the pubic arch at implantation and the risks of acute retention after seed implantation. Especially large median lobes are considered a risk [12]. Cytoreduction with androgen deprivation is an option where these risks are considered significant. The relative indica- tions for a seed implant defined in the ESTRO/EAU guidelines [9] are shown in table 21.2: Tumour characteristics: The most significant prognostic features are the presenting PSA, Gleason score and stage. • Low risk patients with a PSA of less than 10, a Gleason score of 6 or less and stage T1C to T2A should do well with brachyther- apy alone. • Patients with a PSA of 10 to 20, a Gleason score of 7 and stage T2B to T2C are at intermediate risk and may also be considered for seed brachytherapy. • High risk patients with a PSA of more than 20, a Gleason score of more than 7 and/or T3 disease do less well and other treat- ments or additional adjuvant therapy may be indicated. Patient characteristics: Patients should be fit enough for a brachytherapy procedure. Functional outcome is related to prostate size, IPSS and history