CUA: Small Renal Masses (2015)

See Original Guideline

Background

• Definition of small renal mass (SRM):

1. • Enhancing tumours
   • <4 cm in diameter
   • with image characteristics consistent with stage T1aN0M0 renal cell carcinoma

• Most SRMs are RCCs, ≈20-25% of SRMs are benign
• Even if SRMs are malignant, most of them grow slowly
• Small RCCs may be associated with metastatic disease at diagnosis in up to 8% of cases, so initial staging of all SRM patients is essential

1. • Recall 2014 CUA Surgical Management of Renal Cell Carcinoma Consensus Statementrecommended investigations
     • History and physical
     • Labs: CBC, Cr, LFTs, calcium
     • Imaging: cross-sectional of primary tumour, CXR/CT

• Based on current data, initial active surveillance (AS) with delayed treatment for local progression appears to be a relatively safe initial management strategy

Role of needle core biopsy of SRMs

• Biopsy appears safe and at least 80% of first biopsies are diagnostic. Repeat biopsy may be considered.
• Multiple tumours may have different histology and tumour grade, so multiple and repeat biopsies may be required to accurately characterize tumour histology.
• Biopsy for histologic characterization should be reserved for patients in whom the results might change management
• However, biopsy is not yet a standard of care in Canada

Management of SRMs

• Options:
  • Partial nephrectomy (recommended)
  • Laparoscopic radical nephrectomy
    • Reserved for tumours not amenable to partial nephrectomy
  • Thermal ablation (RFA or cryotherapy)
    • A biopsy should be obtained before or at the time of ablation
    • Morbidity is low; can be performed on an outpatient basis without general anesthesia in a cost-effective manner
    • Attractive approach in elderly and comorbid patients
    • Long-term follow-up with imaging is required and local recurrence occurs in up to 14% of patients.
    • Success rates decrease in tumours >3 cm in diameter
  • Active surveillance
    • Low rates of progression, including a low rate of metastasis of 1-2%
      • Likely underestimate as studies have limited follow-up and most SRMs are not biopsy proven to be cancer
    • Long-term follow-up is required to establish the safety of this approach in the young and fit patient.
    • Prognostic factors for progression are poorly understood, but primary tumour growth rate is the most widely used trigger for delayed treatment
    • Active surveillance with regular radiographic follow-up should be a primary consideration for SRMs in elderly and/ or infirm patients with multiple comorbidities that would make them high risk for intervention, and in those with limited life expectancy
    • Suggested follow-up: computed tomography (CT) or magnetic resonance imaging every 3 months in the first year, every 6 months in the next 2 years and every year thereafter. US may be reasonable to substitute for CT/MRI