4. STAGING AND CLASSIFICATION SYSTEM
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 [7] (Table 4.1). It should be noted that there is a separate TNM staging system for prostatic UC [7]. Of note, for cancers occurring in the urethral diverticulum, stage T2 is not applicable as urethral diverticula are lacking periurethral muscle [32].
Table 4.1: TNM classification (8th edition) for urethral carcinoma [7]
| TNM classification (8th edition) for urethral carcinoma | |
| 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). In primary urothelial carcinoma histological subtypes are extremely rare. Table 4.2 lists the different grading systems according to the WHO 2022 system [33].
Table 4.2: Histopathological grading of urothelial and non-urothelial primary urethral carcinoma [33]
| 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 [34].
Table 4.3: Required and recommended elements for pathology reporting of carcinoma of the urethra in urethrectomy specimens [7, 34]
| 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 2022 WHO grading system for pathological staging and grading of primary urethral carcinoma. | Strong |