MRI for managing intermediate & low risk prostate cancer

Intermediate risk disease

Pathological status: PSA 10–20 ng/mL, or biopsy Gleason score 7, or clinical stage T2b or T2c

Clinical note: Heterogeneous group with a wide incidence of biochemical relapse & numerous curative therapy options.

Problems with categorization: Detection of unfavourable subgroup includes Gleason ≥4+3 and/or >50% positive biopsies and/or >1 intermediate risk factors [1, 2]

Role of MRI in practice:

• 1. If initial active surveillance is considered, then it is important not to underestimate tumor grade/ volume/stage

• 2. For external beam radiotherapy, the presence of unfavourable disease affects duration of adjuvant hormonal therapy.

• 3. For focal therapy, index lesion localization is needed

• 4. For surgery, accurate staging to enable curative treatment with negative margins & nerve sparing if possible

Type of MRI [3]:

• Lesion detection and localisation protocol with T2W, DW-MRI and DCE-MRI ± MRSI for low ADC lesions to assess aggressiveness

• Staging with multi-planar T2W, DW-MRI ± DCE-MRI for ECE/SVI

High risk disease

Pathological status: PSA >20 ng/mL, or Gleason score 8–10, or clinical stage >T2c

Clinical note: Highest risk of biochemical recurrence and cancer specific mortality but substantial population heterogeneity

Prognostic subgroups [4]:

■ Good prognosis subgroup: one single risk factor (any)

■ Intermediate prognosis subgroup: two risk factors (PSA >20 ng/ml and stage cT3–4); No Gleason 8+ disease

■ Poor prognosis subgroup: GS >7 and stage cT3–4 and/or PSA >20 ng/ml

Clinical sub-groups: localized, locally advanced & metastatic

Problems with categorization: Local staging accuracy & the detection of metastatic disease

Role of MRI in practice

• 1. local and nodal staging: to detect extensive ECE/SVI that would preclude radical surgery with negative margins. Nerve sparing rarely undertaken.

• 2. To detect nodal and bone metastases

Type of MRI [3, 5]:

• Accurate local staging and pelvic nodal assessments

• Bone scan + CT abdomen or WB-MRI