Fact-sheet: Prostate cancer


Updated on 05/09/2023 at 9:01 AM

Note : 10/10 ( 3 notes )
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Definition

Most common cancer in men > 50 years old.

Histology: prostatic adenocarcinoma in most cases.

Peripheral zone: approximately 70% of prostate cancers

Prostatic sarcoma and neuroendocrine carcinoma are exceptional.

No mass screening.

Individual screening (PSA level and digital rectal exam):

- from age 45 if of African or Afro-Caribbean descent or with a family history of prostate cancer

- from age 50 according to patient preference, if life expectancy exceeds 10 years (slow-growing cancer).

Laboratory findings

PSA ng/mL: prostate-specific antigen but not specific to prostate cancer.

Normal < 4 ng/mL

To be correlated with prostate volume: PSA density = PSA / prostate volume in mL

PSA density < 0.15 ng/mL/cm3: very low risk of prostate cancer.

Prostate volume is calculated as follows:
transverse diameter (axial slice) x height (mid-sagittal slice) x anteroposterior diameter (on a mid-sagittal slice, perpendicular to the height), divided by 0.52

Ultrasound

Suprapubic then transrectal

MRI

PI-RADS RECOMMENDATIONS version 2.1 (2019):

Protocol:

- strict axial T2 TSE sequence or oblique perpendicular to the long axis of the prostate

- at least a second orthogonal T2 plane

- +/- a third T2 plane

- axial T1 Dixon sequence

- high-b-value axial diffusion sequence (at least 1400 s/mm2)

- ADC calculation ideally from a separate acquisition with b between 50 and 100 s/mm2

- dynamic contrast injection: dynamic axial T1 fat-sat sequence up to 2 min 30 s with a temporal resolution of 15 sec

Sectorial anatomy:

Common reference framework for radiologists, urologists, and pathologists.

41 sectors (38 for the prostate, 2 for the seminal vesicles, and 1 for the apical urethra).

Prostate divided into:

- right / left

- Base / Mid third or midgland / Apex

- anterior / posterior

Zones:

R Right

L Left

B Base

M Midgland

A Apex

AFS anterior fibromuscular stroma

TZ transition zone

PZ peripheral zone

CZ central zone

a anterior

p posterior

pl posterolateral

pm posteromedial

SV seminal vesicles

U apical urethra

Example: lesion of the left posterolateral portion of the peripheral zone of the prostate base --> report as lesion of sector LB - PZpl

Plot lesions on a diagram +++

Prostate MRI report:

Clinical and biological parameters (PSA, DRE, prior surgery, biopsy…)

Prostate volume and PSA density

Zonal analysis: peripheral / transitional

Analysis of the capsule and the anterior fibromuscular stroma

Analysis of the seminal vesicles

Analysis of the neurovascular bundles

Analysis of the urethra and bladder, tumor-to-distal urethral sphincter distance

Other: effusion, lymph nodes, bone

Mapping: location (sector ++), dimensions and PI-RADS score of lesions with the diagram, dominant lesion

PI-RADS v2.1: score from 1 to 5 based on the risk of clinically significant cancer.

PI-RADS 1-2: low risk of cancerPI-RADS 3: intermediate riskPI-RADS 4-5: high risk of cancer

Concept of dominant sequence and secondary sequence: the dominant sequence determines the PI-RADS score. The secondary sequence may result in a PI-RADS upgrade (detailed below).

FOR THE PERIPHERAL ZONE:

Dominant sequence = diffusionSecondary sequence = contrast-enhanced sequenceLesions measured on ADC.

PZ diffusion PI-RADS:

1) no abnormality (homogeneous normal signal on all sequences) - PI-RADS 1

2) linear or triangular ADC hypointensity and/or diffusion hyperintensity - PI-RADS 2.

3) focal moderate ADC hypointensity and/or focal moderate diffusion hyperintensity. The lesion may show marked ADC hypointensity or marked diffusion hyperintensity but not both - PI-RADS 3Caution if DCE+ (see below): upgrade from PI-RADS 3 to PI-RADS 4.

4) focal markedly hyperintense diffusion and focal markedly hypointense ADC < 1.5 cm - PI-RADS 4

5) same as 4 but >= 1.5 cm OR invasive features/capsular breach - PI-RADS 5

For information, T2 will show a hypointense nodule, but this sequence does not factor into the PI-RADS score for the peripheral zone.

PZ contrast injection:

DCE+ (Dynamic Contrast Enhancement): focal AND early enhancement AND corresponding to a lesion on T2 or diffusion--> upgrade from PI-RADS 3 to PI-RADS 4.

DCE-: no early enhancement OR multifocal enhancement without correspondence on T2 or diffusion OR focal enhancement corresponding to a benign prostatic hypertrophy nodule.

FOR THE TRANSITION ZONE:

Dominant sequence = T2Secondary sequence = diffusionLesions measured on T2.

TZ T2 PI-RADS:

1) normal appearance (rare, homogeneous, intermediate signal) or typical round, completely encapsulated nodule ("typical nodule" of BPH) - low risk of cancer.

2) incompletely encapsulated nodule OR homogeneous, circumscribed, non-encapsulated nodule ("atypical nodule") OR homogeneous mildly hypointense area between nodules - low risk of cancer.

Caution if diffusion score >= 4: upgrade from PI-RADS 2 to PI-RADS 3.

3) poorly marginated lesion "with indistinct margins" and heterogeneous signal - intermediate risk of cancer.

Caution if diffusion score = 5: upgrade from PI-RADS 3 to PI-RADS 4.

4) lenticular or non-circumscribed, homogeneous, moderate hypointensity and < 1.5 cm in greatest dimension - high risk of cancer.

5) lenticular or non-circumscribed, homogeneous, moderate hypointensity but > 1.5 cm in greatest dimension OR invasive features/capsular breach - high risk of cancer.

TZ diffusion PI-RADS:

1) no abnormality (homogeneous normal signal on all sequences).

2) linear or wedge-shaped diffusion hyperintensity with corresponding ADC drop of the same shape - low risk of cancer.

3) focal moderate diffusion hyperintensity and mild focal ADC hypointensity, distinct from the rest of the prostatic parenchyma. The signal may be intense on diffusion or ADC but not on both simultaneously!

4) markedly hyperintense (very bright) focal diffusion signal and markedly hypointense focal ADC < 1.5 cm.Upgrades a T2 PI-RADS 2 to PI-RADS 3.

5) same as 4 but > 1.5 cm in greatest dimension OR invasive features/capsular breach.Upgrades a T2 PI-RADS 2 to PI-RADS 3.Upgrades a T2 PI-RADS 3 to PI-RADS 4.

Regarding capsular breach:

- mass > 10 mm in contact with the capsule- regular or irregular capsular bulge- asymmetry or involvement of the neurovascular bundles- obliteration of the rectoprostatic angle- invasion of the bladder wall

Regarding seminal vesicle invasion:

- diffuse or focal T2 hypointensity- enhancement- diffusion restriction- obliteration of the angle between the prostate and the seminal vesicles

Classification

PIRADS v2.1 (2019) see MRI

Likert score: subjective score based on the radiologist's confidence - graded from 1 to 5.

  • 1: definitely benign
  • 2: probably benign
  • 3: indeterminate
  • 4: probably malignant
  • 5: definitely malignant

2016 TNM classification:

  • Tx Primary tumor not assessable
  • T0 No primary tumor identified
  • T1 Tumor not palpable on DRE and not visible on imaging T1a: <= 5% of resected tissue with Gleason score <7 or absence of grade 4 or 5
  • T1b: > 5% of resected tissue or Gleason score >= 7 or presence of grade 4 or 5
  • T1c: Identified due to elevated PSA
  • T2: Tumor confined to the prostate
  • T2a: involving half of one lobe or less
  • T2b: involving more than half of one lobe but not both lobes
  • T2c: involving both lobes
  • T3 Extracapsular extension T3a: unilateral or bilateral
  • T3b: seminal vesicle involvement, unilateral or bilateral
  • T4: Tumor fixed or invading structures other than the seminal vesicles (sphincter, rectum, levator ani muscle, pelvic wall)
  • Nx: Regional lymph nodes not assessable
  • N0: No regional lymph node metastasis
  • T1: Regional lymph node involvement T1mi: Lymph node metastasis <= 0.2 cm (optional)
  • Mx: Distant metastases not assessable
  • M0: No distant metastasis
  • M1: Distant metastasis(es) M1a: Non-regional lymph nodes
  • M1b: Bone
  • M1c: Other sites

D'Amico score: grades aggressiveness at diagnosis (based on PSA/Gleason score/TNM) as low, intermediate, or high risk

Gleason score: pathological classification of the degree of aggressiveness (tumor differentiation) by adding the 2 most represented grades (from 1 to 10).

Differential diagnosis

- benign prostatic hyperplasia nodules

- chronic prostatitis

- post-biopsy hemorrhage (axial T1 Dixon sequence ++)

- cyst

- calcification