prostate cancer radiotherapy

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Radiotherapy meeting

Prostate cancerMohamed M. AlhefnyAnatomyProstate gland consists of:The peripheral zone (70% of glandular prostate and site of nearly all cancers). The central zone (25% of the glandular prostate).The transition zone (surrounding the urethra and the site of BPH).The anterior fibromuscular stroma.

The normal prostate epithelium is composed of :

Basal epithelial cells, expressed cytokeratins 5,14 and p63.Columnar secretory epithelial cells, which express the androgen receptor, PSA, cytokeratins 8, 18, prostate-specific membrane antigen (PSMA), and prostate-specific acid phosphatase(PAP).Rare neuroendocrine cells, that secrete chromogranin A, neuron-specific enolase, and synaptophysin.

Case Resume Male patient 72 years old.Presented with hematuria, frequency for 2 months duration with progressive course.PA/US: enlarged prostate 45 cc with irregular borders.TRUS guided biopsies ( 6 core biopsies ):GS: 4+3= 7.Involvement of more than 90% in one core biopsy.Involvement of more than 50% in 4 core biopsies.Total PSA: 40 ng/mL.MRI Pelvis: Prostatic enlargement. ECE Invasion of SV. No pelvic LNs detected.Bone scan: Free. CT/ chest: Free.

Risk Categories:Low: T1-2a and GS 6 and PSA 20 (very high T3b-T4).

NCCN risk categories added 2 risk groups:

Very low: T1c, GS50% + biopsies) or high-risk disease.

LNs included in the CTV : common, internal and external iliac, presacral, hypogastric and obturator lymph nodes.

The PTV is defined with a 3D margin around the CTV to include an internal margin accounting for physiological variations & motion and a set-up margin.The standard margin is 10 mm grown isotropically around the CTV. To limit the dose to the rectum, the posterior margin is reduced to 5 mm if verification studies allowRadiation techniques cont.RTOG GU Consensus on pelvic LN CTV volumes:

Commence contouring the pelvic CTV LN volumes at the L5/ S1 interspace (the level of the distal common iliac and proximal presacral lymph nodes).Place a 7-mm margin around the iliac vessels connecting the external and internal iliac contours on each slice, carving out bowel, bladder, and bone. Contour presacral lymph nodes from S1 through S3, posterior border being the anterior sacrum, and anterior border approximately 10 mm anterior to the anterior sacral bone carving out bowel, bladder, and bone.Stop external iliac CTV lymph node contours at the top of the femoral heads (bony landmark for the inguinal ligament).Stop contours of the obturator CTV lymph nodes at the top of the symphysis pubis.Delineation

RTOG Consensus on pelvic LN CTV volumes

RTOG Consensus on pelvic LN CTV volumes

RTOG Consensus on pelvic LN CTV volumes

33/93RTOG Consensus on pelvic LN CTV volumes

35/93RTOG Consensus on pelvic LN CTV volumes

36/93RTOG Consensus on pelvic LN CTV volumes

39/93RTOG Consensus on pelvic LN CTV volumes

40/93RTOG Consensus on pelvic LN CTV volumes

42/93RTOG Consensus on pelvic LN CTV volumes

45/93RTOG Consensus on pelvic LN CTV volumes

47/93RTOG Consensus on pelvic LN CTV volumes

51/93RTOG Consensus on pelvic LN CTV volumes

53/93RTOG Consensus on pelvic LN CTV volumes

56/93RTOG Consensus on pelvic LN CTV volumes

61/93RTOG Consensus on pelvic LN CTV volumes

63/93RTOG Consensus on pelvic LN CTV volumes

64/93Contouring of Prostate

Contouring of Prostate

Our unit decide to treat:Prostate + S.V & prophylactic Pelvic LNs in phase1Prostate + S.V phase 2

Delineation of our unit illustrated in the following slides:

Radiation techniques cont.Field arrangement:

When treating the pelvic lymph nodes, an anterior and two wedged lateral beams are used, with a posterior beam if necessary.

When treating the prostate, the common approach is to use a technique with an anterior and two wedged posterior oblique beams +/- wedged lateral beams may spare more normal rectum, and four or six coplanar beam arrangements may reduce doses to the OAR further.

CONVENTIONAL:AP/PA Fields:superior = L5/S1 inferior = 0.51 cm below the area where the dye narrows on the urethrogram.lateral = 1.5 cm lateral to the bony pelvis.lateral fields:Anterior border: anterior to the symphysis pubis.Posterior border: splits the sacrum at S2/3.

3 Field arrangement (Ph 1)5 fields arrangement(ph 2)

Retrograde urethrogram

Radiation techniques cont.Dose: Single phase:Prostate + base of the seminal vesicles (SV) (or whole SV if involved): 70-78GY.

Two phases (in case of prophylactic irradiation to SV): Phase 1Prostate + whole SV : 54-56 GY.Phase 2Prostate only : 70-78GY.

Three phases (in case of prophylactic irradiation to SV+LNs):Phase 1Prostate + whole SV + pelvic LNs ( WPI): 46 GY.Phase 2Prostate + base of the seminal vesicles (SV) (or whole SV): 54-56 GY.Phase 3Prostate only (+ SV if involved): 70-78GY.

Radiation techniques cont.Dose escalation:

Hypofractionation

CHIPP trial

Conventional versus hypofractionated high-dose intensitymodulated radiotherapy for prostate cancer: Preliminary safety results from the CHHiP randomized controlled trialTREATMENT ARMS:1) 74 Gy in 37 fractions (n=153)1) 60 Gy in 20 fractions (n=153)3) 57 Gy in 19 fractions (n=151)Radiotherapy with Hypofractionated high-dose radio-therapy seems equally well tolerated as conventionally fractionated treatment at 2 years. Dearnaley D et al. Lancet Oncol.2012Radiation techniques cont.Verification:

Electronic portal images are taken and compared with DRRs from the planning CT scan, using bony landmarks, the beam edges and centre.

The use of radio-opaque fiducial markers within the prostate allows variations arising from prostate movement to be identified and incorporated into the local protocol.OAR and Normal tissue tolerance

Femoral heads : V50< 50%

ToxicityAcute 60% in 3rd week of RTRectal: Diarrhea: 25-75%. Rectal irritation, pain &discomfort: 10-20%. Tenesmus. Urinary:frequency, urgency, nocturia.Urinary incontinence (any 060%, severe 215%).Fatigue.Late: Chronic diarrhea , proctitis, rectal-anal stricture.Bleeding PR- 3.3%, bowel obst./ perforation- 0.6%Rectal toxicity is propotional to volume of rectal wall exposed to high dose (any 2100%, severe 020%) .Urinary stricture

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