Extent Of Local Tumour Spread

Blocks

Due to tumour heterogeneity and variation in direct extension, multiple blocks of tumour and adjacent structures should be taken to ensure a representative sample. A useful general principle is one block per centimetre diameter of tumour mass with targeting of specific areas, e.g. solid foci in ovarian tumours, haemorrhagic foci in testicular tumours (choriocarcinoma).

Colorectal carcinoma: 4 or 5 blocks to show the tumour in relation to mucosa, wall, serosa and mesentery.

Thyroid nodule: 8 to 10 blocks including the capsule to distinguish fol-licular adenoma from minimally invasive follicular carcinoma. Ovarian tumours: 1 block/centimetre diameter to account for the spectrum of benign, borderline and malignant changes in one lesion, particularly mucinous tumours.

Border

Pushing/infiltrative.

Lymphocytic reaction

Prominent/sparse.

Carcinomas with a pushing border and prominent lymphocytic reaction are regarded as having a better prognosis than those with a diffusely irregular infiltrating margin and sparse lymphocytic reaction, e.g. col-orectal carcinoma, head and neck carcinoma, malignant melanoma, medullary carcinoma of breast, advanced gastric carcinoma.

3Tumour necrosis: apoptotic (single cell) or coagulative (confluent with pyknotic nuclear material in eosinophilic debris).

Perineural spread

Carcinoma prostate, gall bladder and extrahepatic bile duct, pancreas and adenoid cystic carcinoma. In prostatic cancer there is some evidence that perineural invasion relates to the presence of extracapsular spread of disease and in other cancers it increases the likelihood of local recurrence.

Breslow depth/Clark level

Malignant melanoma. Direct linear measurement (mm) and anatomical level of invasion of the vertical component are strong prognostic indicators.

TNM (Tumour Nodes Metastases) classification

The TNM classification is an international gold standard for the assessment of spread of cancer and the revised 6th edition has been published by the UICC (International Union Against Cancer) taking into account new prognostic information, investigations and treatments. The system has evolved over 50 years as a tool for the careful collection of accurate data pertaining to cancer spread which can then be consistently related to planning of treatment, prognosis, evaluation of treatment and exchange of information between clinicians and centres. Virtues are that it translates into hard data some of the subjective language used in descriptive pathology reports and also encourages the pathologist to be more analytical in approach. It also improves pathologist-to-clinician communication. The post-surgical histopathological classification is designated pTNM and is based on pre-treatment, surgical and pathological information.

pT requires resection of the primary tumour or biopsy adequate for evaluation of the highest pT category or extent of local tumour spread pN requires removal of lymph nodes sufficient to evaluate the absence of regional node metastasis (pN0) and also the highest pN category pM requires microscopic examination of distant metastases which is often not available to the pathologist and therefore designated on clinical or radiological grounds. If available (e.g. a multidisciplinary meeting), the TNM categories can be stratified into clinical stage groupings which are used to select and evaluate therapy, e.g. carcinoma in situ is stage 0 while distant metastases is stage IV. However, for the most part the pathologist concentrates on pT and pN which gives reasonably precise data to estimate prognosis and calculate end results. Stage grouping is mostly based on the anatomical extent of disease, but for some tumour sites or entities other factors are included: histological type (thyroid), age (thyroid), grade (bone, soft tissue, prostate), tumour markers (testis) and risk factors (ges-tational trophoblastic tumour).

Multiple synchronous tumours (diagnosis within 2 months of each other): classify the tumour with the highest pT category and indicate the number of tumours in brackets, e.g. pT2 (4). In simultaneous bilateral cancers of paired organs each tumour should be classified independently. Systemic or multicentric cancers potentially involving many discrete organs are categorized only once in any individual, e.g. malignant lymphoma, leukaemia, Kaposi's sarcoma and mesothelioma. If there is doubt about the assigned T, N or M category in a particular case then the lower (i.e. less advanced) category is chosen. Note that in practice the multi-disciplinary meeting may choose to upgrade the category to ensure that the patient receives adequate therapy, particularly in younger and fit individuals. When size is a criterion for the pT category, it is a measurement of the actual unfixed invasive component. Adjacent in-situ change is not counted and if the fixed specimen shows a significant discrepancy with the clinical tumour measurement, the latter is chosen.

Direct spread into an adjacent organ is recorded in the pT classification and is not considered distant metastasis, whereas direct spread into a regional lymph node is considered in the pN category.

pT primary tumour pTX primary tumour cannot be assessed histologically pT0 no histological evidence of primary tumour pTis carcinoma in situ pT1, pT2, pT3, pT4 increasing size and/or local extent of the primary tumour histologically pN regional lymph nodes pNX regional lymph nodes cannot be assessed histologically (either not present or less than the number recommended for a regional lymphadenectomy appropriate to the organ concerned)

pN0 no regional lymph node metastasis histologically pN1, pN2, pN3 increasing involvement of regional lymph nodes histologically.

Main categories can be subdivided for further specificity, e.g. pT1a or pT1b to signify unifocality or multifocality.

Note than an X classification does not necessarily signify inadequate staging, e.g. known metastatic disease (pM1) supersedes the pN category, or pNX may arise because of a correct decision to treat by local excision, e.g. therapeutic polypectomy in the colorectum.

The TNM classification is applied to carcinoma only in the majority of tissues. Other qualifying malignant tumours are malignant mesothe-lioma, malignant melanoma, gestational trophoblastic tumours, germ cell tumours and retinoblastoma.

TNM optional descriptors

L lymphatic invasion

LX cannot be assessed L0 not present L1 present.

V venous invasion

VX cannot be assessed V0 not present V1 microscopic V2 macroscopic.

Note that lymphovascular invasion does not qualify as local spread of tumour in the pT classification (except liver and testis).

Prefix y tumour is classified during or after initial multimodality therapy r recurrent tumour, staged after a disease-free interval a classification first determined at autopsy.

Suffix m multiple primary tumours at a single site mi nodal micrometastasis <2mm. i nodal isolated tumour cells (ITC) <0.2mm sn sentinel nodes cy positive pleural or peritoneal washings, e.g. pM1 (cy +). An exception is primary ovarian carcinoma where cy + is part of the pT category.

Where appropriate, other internationally recognized staging systems are also given, e.g.

Malignant lymphoma Ann Arbor

Gynaecological cancers International Federation of Gynaecology and Obstetrics (FIGO)

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