Guidelines

Renal Cell Carcinoma

4. STAGING AND CLASSIFICATION SYSTEMS

4.1. Staging

The Tumour Node Metastasis (TNM) classification system is recommended for clinical and scientific use

[81]. A supplement was published in 2012, and the latter’s prognostic value was confirmed in single- and multi-institution studies [82,83]. Tumour size, venous invasion, renal capsular invasion, adrenal involvement, LN and distant metastasis are included in the TNM classification system (Table 4.1). However, some uncertainties remain:

  • The sub-classification of T1 tumours using a cut-off of 4 cm might not be optimal in NSS for localised cancer [84];
  • The value of size stratification of T2 tumours has been questioned [85];
  • Renal sinus fat invasion might carry a worse prognosis than perinephric fat invasion, but, is nevertheless included in the same pT3a stage group [86-89] (LE: 3);
  • Sub T-stages (pT2b, pT3a, pT3c and pT4) may overlap [83];
  • For adequate M staging, accurate pre-operative imaging (chest and abdominal CT) should be performed [90,91] (LE: 4).

A proposed imaging analysis of Tumor Contour Irregularity might be a valuable tool to enhance the preoperative staging between T1 and T3a RCCs for treatment decisions [92].

The TNM classification should not be considered the only criterion for clinical decision-making, but patient’s condition, comorbidities and wishes are of fundamental importance to select the most optimal treatment. A clinically-guided RCC staging classification was proposed in 2022 by the EAU Panel, based on changes observed in the management of SRM, locally advanced and metastatic disease [84].

Table 4.1: 2017 TNM classification system [93]

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 extends into the renal vein or its segmental branches, or invades the pelvicalyceal system or invades perirenal and/or renal sinus 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

pTNM stage grouping

Stage I

T1

N0

M0

Stage II

T2

N0

M0

Stage III

T3

N0

M0


T1, T2, T3

N1

M0

Stage IV

T4

Any N

M0


Any T

Any N

M1

A help desk for specific questions about TNM classification is available at http://www.uicc.org/tnm.
*Adapted based on the American Joint Committee on Cancer (AJCC), 8th Edn. 2017 [94].

4.2. Anatomic classification systems

Objective anatomic classification systems, such as the Preoperative Aspects and Dimensions Used for an Anatomical (PADUA) classification system, the R.E.N.A.L. nephrometry score, the C-index, an Arterial Based Complexity (ABC) Scoring System and Zonal NePhRO scoring system, have been proposed to standardise the description of renal tumours [95-97]. These systems include assessment of tumour size, exophytic/endophytic properties, proximity to the collecting system and renal sinus, and anterior/posterior or lower/upper pole location.

The use of such a system is helpful as it allows objective prediction of potential morbidity of NSS and tumour ablation techniques. These tools provide information for treatment planning, patient counselling, and comparison of PN and tumour ablation series. However, when selecting the most optimal treatment option, anatomic scores must be considered together with patient features and surgeon experience.