Karan Wadhwa
With the rise in use of cross‐sectional imaging, renal masses are increasingly being diagnosed and present a common referral to the urologist both acutely and on an outpatient basis. This chapter will present a brief overview of the diagnosis and provide guidance on the management of renal masses.
Renal cancer makes up 2–3% of all cancer diagnoses with an increase in 2% over the past 20 years. 40% are diagnosed at a late stage, and renal cancer accounts for 3% of all cancer deaths, however kidney cancer survival overall has increased over the last 40 years. Men are more likely to be diagnosed than women (1.5 : 1), with a peak incidence between the ages of 60–70 and more likely in white races than Asians or black races.
The main risk factors for developing renal cancer appear to be hypertension, smoking, and obesity. The genomic changes for the development of renal cancer start in childhood or adolescence and there is an increased risk with an affected first‐degree relative. Several genetic conditions also predispose to renal cancer such as Von‐Hippel Lindau disease, but only 8–10% of renal cancers are hereditary.
The most common histological subtype of renal cancer is clear cell renal cell carcinoma (ccRCC), which also has the worst overall survival compared to papillary or chromophobe cancers. Papillary type renal cancer can be divided into type 1 and type 2 with distinct genetic features but overall with a higher survival rate than ccRCC. Lastly, chromophobe renal cancer has a myriad of genetic changes but has the best recurrence free and overall survival of the three main subtypes (see Table 20.1). Several other subtypes exist, but these make up only 10–15% of renal cancers and have variable clinical courses.
Onset of renal cancer is usually insidious, and over half of renal cancers are diagnosed incidentally. The classic triad of loin pain, palpable flank mass, and visible haematuria is fortunately rare (6–8%) and usually indicates a poor prognosis. Up to one‐third of patients may suffer a paraneoplastic syndrome for example deranged LFTS (Stauffer's syndrome). Breathlessness or cough may indicate lung metastases or pulmonary emboli and likewise back pain may indicate a metastatic process.
Abdominal signs are usually absent, but one must be mindful to examine for chest/abdominal lymphadenopathy, a flank mass, or a varicocele (particularly right‐sided).
Alongside clinical examination, urine should be dipped for haematuria, and baseline bloods including full blood count, urea, and electrolytes, liver function tests, bone profile, and lactate dehydrogenase should be measured in clinic. Aside from clinically diagnosed tumours, the patient usually comes to hospital with imaging such as an abdominal/renal ultrasound or CT scan. To accurately stage a patient with suspected renal cancer, a dedicated CT of chest, abdomen, and pelvis should be performed with contrast. The key features of a renal mass are size, location, enhancement (>20–30 Hounsfield units), invasion e.g. renal vein/IVC or adrenal, lymph node status, and metastases (lung/liver/bone). It is also important to consider the contralateral kidney in terms of presence, size, and shape.
Table 20.1 Subtypes of renal cancer.
Source: Adapted from EAU guidelines (Ljungberg et al. 2018).
| Cancer‐specific survival | 5 years (%) | 10 years (%) | 15 years (%) | 20 years (%) |
|---|---|---|---|---|
| Clear‐cell RCC | 71 (69–73) | 62 (60–64) | 56 (53–58) | 52 (49–55) |
| Papillary RCC | 91 (88–94) | 86 (82–89) | 85 (81–89) | 83 (78–88) |
| Chromophobe RCC | 88 (83–94) | 86 (80–92) | 84 (77–91) | 81 (72–90) |
In case of any diagnostic doubts, or if the patient has poor renal function, an MRI can be considered. Magnetic imaging resonance can also be used for operative planning in the case of inferior vena cava (IVC) thrombus, to assess extent of invasion and the need to mobilise the liver if the caval tumour thrombus encroaches the hepatic veins.
Dimercaptosuccinic acid (DMSA) may be useful in the case of a small contralateral kidney or if the patient has poor renal function to predict the need for peri or post‐operative renal replacement therapy.
Staging is performed using the TNM (tumour location, lymph node involvement, metastatic spread) classification.
2017 TNM classification system
| T – Primary tumour | ||||
| TX | Primary tumour cannot be assessed | |||
| T0 | No evidence of primary tumour | |||
| T1 | Tumour <7 cm or less in greatest dimension, limited to the kidney | |||
| T1a | Tumour <4 cm or less | |||
| T1b | Tumour >4 cm but <7 cm | |||
| T2 | Tumour >7 cm in greatest dimension, limited to the kidney | |||
| T2a | Tumour >7 cm but <10 cm | |||
| T2b | Tumours >10 cm, limited to the kidney | |||
| T3 | Tumour extends into major veins or perinephric tissues but not into the ipsilateral adrenal gland and not beyond Gerota fascia | |||
| T3a | Tumour grossly extends into the renal vein or its segmental (muscle‐containing) branches, or tumour invades perirenal and/or renal sinus fat (peripelvic fat), but not beyond Gerota fascia | |||
| T3b | Tumour grossly extends into the vena cava below diaphragm | |||
| T3c | Tumour grossly extends into vena cava above the diaphragm or invades the wall of the vena cava | |||
| T4 | Tumour invades beyond Gerota fascia (including contiguous extension into the ipsilateral adrenal gland) | |||
| N – Regional lymph nodes | ||||
| NX | Regional lymph nodes cannot be assessed | |||
| N0 | No regional lymph node metastasis | |||
| N1 | Metastasis in regional lymph node(s) | |||
| M – Distant metastasis | ||||
| M0 | No distant metastasis | |||
| M1 | Distant metastasis | |||
The role of biopsy for renal cancer has been controversial in the past; however, it has recently seen a resurgence and can be safely performed as an ambulatory procedure. Biopsy is mainly indicated for those in whom we are considering active surveillance, ablative therapy, or if there is diagnostic uncertainty in the context of metastatic disease. Cystic masses are not ideal for biopsy. Concordance between biopsy histology and final specimen pathology is greater than 95%, and with the coaxial approach, biopsy yield is high. Although biopsy is generally a safe procedure, it does carry with it the risk of bleeding (4%) but clinically significant haemorrhage is rare. Biopsy tract seeding, although described, is very rare.
The management of renal masses can be divided into small renal mass (T1), renal mass (T2), or metastatic RCC (mRCC). The multidisciplinary team comprising radiology, pathology, and urology renal cancer surgeons are vital in the decision‐making process, taking into account patient, tumour, and resource factors.
Studies have shown no difference in cancer specific outcomes between radical and partial nephrectomy, and preservation of GFR has been shown to increase overall survival (Go et al. 2004), but studies have yet to prove an overall survival benefit from partial nephrectomy. Despite this, many authors propose doing a partial nephrectomy when possible, especially for a T1 mass. However, active surveillance is a valuable option, particularly for the more elderly or co‐morbid patient. Progression on active surveillance to metastatic disease is rare (1%), and tumours are generally slow growing. Minimally invasive treatment such as renal radiofrequency ablation or cryotherapy may have a role in management of the small renal mass. Treatment such as RFA or cryotherapy may be indicated in the unfit or elderly patient, by patient choice, or for example, if there is radiological or clinical progression whilst on surveillance in a patient who does not want surgery.
Laparoscopic radical nephrectomy is the accepted standard of care for the >T1 renal mass and it is widely performed. The ipsilateral adrenal gland or lymph nodes are not routinely taken, unless there is clinical indication such as radiological extension. Open nephrectomy is now reserved for the very large renal mass, or if renal vein/IVC thrombus is suspected.
In the unfit patient with haematuria or flank pain, embolization of the tumour may be deployed in a palliative setting.
In the context of mRCC, systemic therapy such as tyrosine kinase inhibitors are generally preferred if the disease burden outside of the kidney is high. Newer agents such as the Programmed death‐ligand 1 (PDL1) inhibitor Nivolumab have shown promise in clinical trials. Cytoreductive nephrectomy is reserved for palliation but may still have a role, for example, in those with low volume metastatic disease with a good performance status and favourable risk scores (Memorial Sloan Kettering Cancer Center/International Metastatic RCC Database Consortium [MSKCC/IMDC] <4). Evidence for surgical management of mRCC is poor as trials are difficult to run and recruit to.
Laparoscopic/robotic partial or radical nephrectomy is an operation conducive for short stay surgery. Many patients can be discharged the next post‐operative day. This relies on a motivated, appropriately counselled patient and functional enhanced recovery programme. Techniques such as catheter‐less nephrectomy, mobilising the patient very early the next post‐operative day and consultant‐review‐driven discharge can reduce length of stay.