Guidelines

Primary Urethral Carcinoma

4. STAGING AND CLASSIFICATION SYSTEMS

4.1. Tumour, Node, Metastasis (UICC/TNM) staging system

In men and women, urethral carcinoma is classified according to the 8th edition of the TNM classification [9] (Table 4.1). It should be noted that there is a separate TNM staging system for prostatic UC [9]. Of note, for cancers occurring in the urethral diverticulum, stage T2 is not applicable as urethral diverticula are lacking periurethral muscle [33].

Table 4.1: TNM classification (8th edition) for urethral carcinoma [9]

T - Primary Tumour

TX

Primary tumour cannot be assessed

T0

No evidence of primary tumour

Urethra (male and female)

Ta

Non-invasive papillary, polypoid, or verrucous carcinoma

Tis

Carcinoma in situ

T1

Tumour invades subepithelial connective tissue

T2

Tumour invades any of the following: corpus spongiosum, prostate, periurethral muscle

T3

Tumour invades any of the following: corpus cavernosum, beyond prostatic capsule, anterior vagina, bladder neck (extraprostatic extension)

T4

Tumour invades other adjacent organs (invasion of the bladder)

Urothelial (transitional cell) carcinoma of the prostate

Tis pu

Carcinoma in situ, involvement of prostatic urethra

Tis pd

Carcinoma in situ, involvement of prostatic ducts

T1

Tumour invades subepithelial connective tissue (for tumours involving prostatic urethra only)

T2

Tumour invades any of the following: prostatic stroma, corpus spongiosum, periurethral muscle

T3

Tumour invades any of the following: corpus cavernosum, beyond prostatic capsule, bladder neck (extraprostatic extension)

T4

Tumour invades other adjacent organs (invasion of the bladder or rectum)

N - Regional Lymph Nodes

NX

Regional lymph nodes cannot be assessed

N0

No regional lymph node metastasis

N1

Metastasis in a single lymph node

N2

Metastasis in multiple lymph nodes

M - Distant Metastasis

M0

No distant metastasis

M1

Distant metastasis

4.2. Tumour grade

Non-urothelial urethral carcinoma is graded by a trinomial system that differentiates between well-differentiated (G1), moderately-differentiated (G2), and poorly-differentiated tumours (G3). Table 4.2 lists the different grading systems according to the WHO 1973 and 2004 systems [34]. The 2004 classification corresponds to the 2016 WHO classification [35].

Table 4.2: Histopathological grading of urothelial and non-urothelial primary urethral carcinoma [34]

Urothelial urethral carcinoma

PUNLMP

Papillary urothelial neoplasm of low malignant potential

Low grade

Well differentiated

High grade

Poorly differentiated

Non-urothelial urethral carcinoma

Gx

Tumour grade not assessable

G1

Well differentiated

G2

Moderately differentiated

G3

Poorly differentiated

4.3. Handling of tumour specimens

Specimen handling should follow the general rules as published by the International Collaboration on Cancer Reporting [36].

Table 4.3: Required and recommended elements for pathology reporting of carcinoma of the urethra in urethrectomy specimens [9,36]

Required

Recommended

Operative procedure


Clinical information

Previous history of urinary tract disease or distant metastasis

Additional specimens submitted



Previous therapy

Maximum tumour dimension

Cannot be assessed


Other clinical information

No macroscopically visible tumour

Tumour focality


Maximum tumour dimension (largest tumour)

Other tumour dimensions (than maximum dimension) of the largest tumour


Macroscopic tumour site


Block identification key


Macroscopic extent of invasion


Associated epithelial lesions


Histological tumour type

Histological subtype/variant (urothelial carcinoma)

Extranodal spread for involved regional lymph node(s)


Non-invasive carcinoma


Coexistent pathology


Histological tumour grade


Ancillary studies


Microscopic extent of invasion




Lymphovascular invasion




Margin status




Regional lymph node status

No regional lymph nodes submitted



4.4. Guideline for staging and classification systems

Recommendation

Strength rating

Use the 2017 TNM classification and 2004/2016 WHO grading systems for pathological staging and grading of primary urethral carcinoma.

Strong