Renal cell carcinoma: what to do when imaging finds a kidney mass

What is renal cell carcinoma?

Renal cell carcinoma (RCC) is a malignancy arising from the tubular cells of the kidney. It is the most common form of kidney cancer in adults, with approximately 4,000 new diagnoses per year in Australia, according to Cancer Council Australia’s Optimal Care Pathway for Kidney Cancer (2022). Men are affected about 1.5–2 times more often than women, and the peak incidence is in the sixth and seventh decades of life.

More than 60% of RCC diagnoses are now made incidentally — a mass discovered on a scan ordered for a back complaint, abdominal pain, or some entirely unrelated reason. The RACGP has published specific general practice guidance on this growing challenge. The shift toward incidental detection reflects how commonly cross-sectional imaging is now used in Australian clinical practice.

The five-year survival for all stages combined is approximately 80%. For localised disease, survival exceeds 95%.

A. Core clinical — the AU general practice framework

Histological subtypes

The EAU Renal Cell Carcinoma Guideline 2024 describes the major subtypes:

Clear cell RCC (~75%) — the dominant subtype, driven by loss of the VHL tumour suppressor gene. Clear cell RCC is highly vascular (explaining its enhancement on imaging) and is the subtype most responsive to modern immunotherapy and VEGF-targeted therapies.

Papillary RCC (10–15%) — two types: type 1 is typically indolent and MET-driven; type 2 is more aggressive and associated with hereditary leiomyomatosis and RCC syndrome (HLRCC).

Chromophobe RCC (~5%) — generally better prognosis. Oncocytoma (a benign tumour in the same cellular family) accounts for 5–7% of all renal masses and cannot be reliably distinguished from chromophobe RCC on imaging alone — biopsy may be required.

Sarcomatoid features — a pattern of dedifferentiation that can occur in any subtype; carries the worst prognosis but paradoxically shows the highest response rates to immunotherapy.

Risk factors

The three most important modifiable risk factors are:

1. Smoking — approximately doubles the risk. Cessation reduces risk over 10–15 years.
2. Obesity (BMI ≥30) — approximately doubles the risk, particularly for clear cell RCC.
3. Hypertension — an independent risk factor, not solely attributable to antihypertensive medications.

Other significant factors include chronic kidney disease and dialysis (up to 7-fold risk), end-stage renal failure, trichloroethylene occupational exposure, and hereditary syndromes (~4% of all RCC) — discussed under Special Populations.

Presentation and red flags in general practice

Incidental detection (>60%): No symptoms; found on imaging for another reason.

Haematuria (40%): Visible blood in urine, typically painless. Every episode of visible haematuria in an adult requires investigation. See [[haematuria-workup]].

Flank pain (30%): Dull, aching — not the colicky pain of urolithiasis.

Classic triad (haematuria + flank pain + palpable mass): Present in only 6–10% and almost invariably indicates locally advanced disease.

Paraneoplastic syndromes (~20%): Hypercalcaemia (from PTHrP secretion), erythrocytosis (from ectopic EPO production), hypertension (from renin), and Stauffer syndrome (non-metastatic hepatic dysfunction that reverses with nephrectomy).

Two GP red flags requiring same-week imaging:

1. New right-sided varicocele in an adult man — left-sided varicoceles are common and anatomically explained. An isolated new right-sided varicocele raises concern for a right kidney tumour with IVC thrombus compressing the right internal spermatic vein. Arrange renal imaging within one week.
2. Constitutional symptoms with a known renal mass — weight loss, fever, drenching night sweats — suggest metastatic disease.

Bosniak classification — how to read the radiology report

The Bosniak v2019 update (Silverman et al., Radiology 2019) classifies cystic renal masses:

Category	Description	Malignancy risk	Action
I	Simple water-density cyst, no enhancement	<1%	No follow-up needed
II	Minimally complex — a few hairline septa or fine calcification	<2%	No follow-up needed
IIF	More septa, slightly thickened wall, perceived but not measurable enhancement	~6–11%	Surveillance CT/MRI at 6 months, 12 months, then annually for 5 years
III	Thickened irregular walls or septa with measurable enhancement	~50%	Urology referral — surgical excision or specialist-led surveillance
IV	Definite enhancing soft-tissue component	>90%	Urgent urology referral — resection

Never reassure a patient with a “cyst” without confirming Bosniak grading on contrast-enhanced imaging. Ultrasound can identify a cyst but cannot adequately characterise cystic complexity or enhancement. A renal mass reported as “indeterminate on ultrasound” should proceed to multiphase contrast CT.

Investigations

For a solid or indeterminate renal mass:

• Multiphase contrast CT abdomen — MBS item 56507 — the cornerstone investigation. Enhancement of greater than 15–20 HU between pre- and post-contrast phases indicates a vascular lesion and strongly suggests RCC.
• Staging CT chest + abdomen + pelvis — MBS item 56807 — for any solid or suspected malignant mass.
• MRI kidney with contrast — MBS item 63491 — when iodinated contrast is contraindicated (eGFR below 30, contrast allergy, pregnancy) or when the lesion is indeterminate on CT.
• FBC — MBS item 65070 — anaemia of chronic disease or paraneoplastic erythrocytosis.
• UEC and eGFR — MBS item 66500 — critical for nephron-sparing planning; knowing preoperative renal function guides how urgently conservative surgery is needed.
• Corrected calcium, LFTs, LDH — paraneoplastic screen and IMDC prognostic score for advanced disease.
• Urinalysis — haematuria assessment.

B. Evidence appraisal

Active surveillance vs surgery for small tumours (T1a, <4 cm)

The DISSRM prospective cohort (Pierorazio et al., Eur Urol 2015) followed patients with small renal masses under active surveillance and found 5-year cancer-specific survival was 99% under surveillance versus 100% with immediate intervention — effectively equivalent. Growth rate under surveillance was typically less than 0.5 cm per year, and about 25% of patients eventually crossed over to intervention. This evidence supports active surveillance as a reasonable option for elderly or frail patients with T1a lesions, provided structured imaging follow-up occurs.

Partial vs radical nephrectomy for T1–T2 tumours

The EORTC 30904 RCT (Van Poppel et al., Eur Urol 2011) compared radical and partial nephrectomy for tumours up to 5 cm. Radical nephrectomy was not inferior for overall survival in the primary analysis, but partial nephrectomy significantly preserved eGFR and reduced chronic kidney disease progression — a benefit that translates into reduced cardiovascular mortality over time. Current guidelines from both EAU 2024 and USANZ endorse partial nephrectomy as the preferred approach for T1 and selected T2 tumours where technically feasible.

Modern immunotherapy combinations in advanced disease

Three pivotal trials establish the current standard of care for metastatic clear cell RCC:

CheckMate 214 (Motzer et al., NEJM 2018): Nivolumab plus ipilimumab versus sunitinib — complete response rate 9.4% vs 1.2%, and durable 5-year OS of 43% versus 27% in intermediate/poor-risk patients. The dual checkpoint approach produces deeper and more durable responses than single-agent TKI therapy.

KEYNOTE-426 (Rini et al., NEJM 2019): Pembrolizumab plus axitinib versus sunitinib — PFS improved (15.1 vs 11.1 months), OS improved, and benefit extended to all IMDC risk groups, including favourable-risk patients who did less well with nivolumab/ipilimumab.

These combinations are PBS-listed in Australia under Section 100. The right combination depends on IMDC risk group, comorbidities, urgency of response needed, and multidisciplinary team discussion.

Adjuvant pembrolizumab — The KEYNOTE-564 trial (Choueiri et al., NEJM 2021) showed pembrolizumab for 12 months after nephrectomy in high-risk localised or oligometastatic disease significantly improved disease-free survival (HR 0.68). As of mid-2026, this indication is not yet PBS-listed in Australia. Patients may access it via self-funding (approximately AUD 9,000–10,000 per 3-weekly infusion) or compassionate access programs.

C. Australian operations

MBS items

• Standard consult: items 23 / 36 / 44.
• GPCCMP (from 1 July 2025): items 965 and 967 — post-nephrectomy CKD management qualifies.
• Partial nephrectomy: MBS item 36522.
• Radical nephrectomy: MBS items 36516 and 36519.
• Cryoablation (biopsy-confirmed RCC ≤4 cm, MDT-confirmed unsuitability for partial nephrectomy): MBS item 36530, added 1 November 2022.
• MRI surveillance for hereditary renal cancer syndromes (VHL, BHD, HLRCC, tuberous sclerosis, hereditary papillary RCC): MBS items 63539 and 63540 — MSAC-listed.

Post-nephrectomy chronic kidney disease management

Loss of one kidney reduces nephron mass by ~50%, but most people tolerate this well. However, superimposed factors — pre-existing CKD, age, diabetes, hypertension — can lead to progressive eGFR decline. After nephrectomy:

• Monitor eGFR and urine ACR at least 6-monthly.
• Treat hypertension aggressively (target below 130/80 mmHg); ACEi or ARB preferred if proteinuria present.
• Avoid nephrotoxic medications (NSAIDs, long-term aminoglycosides).
• Maintain hydration at 2 L per day where cardiac and renal status allows.
• See [[chronic-kidney-disease]] for the full management framework.

D. Special populations

Hereditary RCC syndromes (~4% of all RCC)

Refer to a Family Cancer Clinic for genetics assessment if any of the following apply:

• RCC diagnosed under age 46.
• Bilateral or multifocal RCC.
• Papillary type 2 RCC with cutaneous leiomyomata (HLRCC — hereditary leiomyomatosis and RCC syndrome).
• Oncocytoma with lung cysts and skin fibrofolliculomata (BHD — Birt-Hogg-Dubé syndrome).
• CNS or retinal haemangioblastoma with RCC or pheochromocytoma (VHL — von Hippel-Lindau disease).
• Family history of RCC in a first-degree relative, especially at young age.

MBS-funded annual surveillance MRI is available for patients with eligible confirmed hereditary cancer syndromes via items 63539/63540. Refer through eviQ Cancer Genetics.

Patients on dialysis or post-transplant

End-stage renal failure and dialysis carry a 5–7-fold increased RCC risk, with the tumours often papillary and multifocal (arising from acquired cystic disease of the dialysis kidney). Surveillance for renal cysts and masses is appropriate in long-term dialysis patients. Post-transplant patients also have increased solid-organ malignancy rates and need regular skin checks and GP surveillance.

Younger patients with advanced disease

For younger, fit patients with metastatic RCC, the immune checkpoint inhibitor combinations (nivolumab/ipilimumab, pembrolizumab/axitinib) have produced complete responses in a meaningful minority — some of which appear durable at 5+ years of follow-up. These patients should be discussed at a multidisciplinary oncology meeting and may wish to consider clinical trial enrolment. The Cancer Council Information and Support line (13 11 20) and Kidney Cancer Australia provide peer support and information.

When to escalate

Urgent urology referral (within 2 weeks, 2-week cancer pathway):

• Solid enhancing renal mass on contrast CT — treat as RCC until proved otherwise.
• Bosniak III or IV cystic lesion.
• New right-sided varicocele — arrange urgent renal imaging first.

Same-day emergency:

• Severe paraneoplastic hypercalcaemia (nausea, confusion, renal failure) — IV fluids, urgent medical admission.
• Frank haematuria with haemodynamic instability.
• Suspected spinal cord compression from metastatic RCC.

Routine (2–4 weeks):

• Bosniak IIF cyst — arrange surveillance imaging schedule with urology.
• Post-nephrectomy CKD progression beyond expected rate.

What this article is and is not

This article provides general information about renal cell carcinoma to help Australian patients understand their diagnosis and the pathway ahead. It is not a substitute for individualised advice from a urologist, medical oncologist, or multidisciplinary team. Staging, histology, genetic testing results, renal function, and patient preferences all influence the right treatment decision — these require specialist evaluation. This information is current to mid-2026 but PBS listings and clinical guidelines evolve, so always verify current options with your treating team.

---

Sources cited

• Cancer Council Australia — Optimal Care Pathway for Kidney Cancer 2022
• RACGP — Incidentally detected small renal masses
• USANZ — Renal cell carcinoma position statement
• EAU — Renal Cell Carcinoma Guideline 2024
• Bosniak v2019 — Silverman et al., Radiology 2019
• CheckMate 214 — Motzer et al., NEJM 2018
• KEYNOTE-426 — Rini et al., NEJM 2019
• KEYNOTE-564 — Choueiri et al., NEJM 2021
• DISSRM — Pierorazio et al., Eur Urol 2015
• Therapeutic Guidelines (eTG)
• PBS — nivolumab+ipilimumab; pembrolizumab combinations
• HealthDirect — Kidney cancer
• Kidney Cancer Australia
• eviQ Cancer Genetics