TABLE 1.
Definition and categorization of tumor deposits (TDs) in staging systems
| Staging system (publication year) | Terminology | Definition | Categorization criteria for tumor staging |
|---|---|---|---|
| TNM5 (1997) | Tumor nodule | A nodule in perirectal or pericolic adipose tissue without histological evidence of a residual lymph node in the nodule. | A tumor nodule of >3 mm in diameter is classified as regional LNM; a tumor nodule up to 3 mm in diameter is classified in the T category as a discontinuous extension, i.e., T3. |
| TNM6 (2002) | Tumor nodule | A tumor nodule in the pericolic or perirectal adipose tissue without histological evidence of residual lymph node in the nodule. | If the nodule has the form and smooth contour of a lymph node, it is classified in the pN category as a regional LNM; if the nodule has an irregular contour, it should be classified in the T category and also coded as V1 (microscopic venous invasion) or V2, if it was grossly evident, because there is a strong likelihood that it represents venous invasion. |
| TNM7 (2009) | Tumor deposits (satellites) | Macroscopic or microscopic nests or nodules in the pericolorectal adipose tissue's lymph drainage area of a primary carcinoma without histological evidence of residual lymph node in the nodule. | If tumor deposits are observed with lesions that would otherwise be classified as T1 or T2, then the T classification is not changed, but the nodule(s) is recorded as N1c. If a nodule is considered by the pathologist as a totally replaced lymph node (generally having a smooth contour), it should be recorded as a positive lymph node and not as a satellite, and each nodule should be separately counted as a lymph node in the final pN determination. |
| TNM8 (2017) | Tumor deposits (satellites) | Discrete macroscopic or microscopic nodules of cancer in the pericolorectal adipose tissue's lymph drainage area of a primary carcinoma that are discontinuous from the primary and without histological evidence of residual lymph node or identifiable vascular or neural structure. |
If a vessel wall is identifiable on H&E, elastic, or other stains, it should be classified as a venous invasion (V1/2) or lymphatic invasion (L1). Similarly, the lesion should be classified as a perineural invasion (Pn1) if neural structures are identifiable. The presence of tumor deposits does not change the primary tumor T category but changes the node status (N) to pN1c if all regional lymph nodes are negative on pathological examination. |
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JSCCR8 (2013) JSCCR9 (2018) |
Extramural cancer deposits without lymph node structure (EX) |
Extramural cancer deposits with no lymph node structure within the regional lymph node area. EX includes localized lesions comprising lymphatic invasion, venous invasion, perineural invasion (vascular/perineural invasion lesions), and other lesions (tumor nodule: [ND]). All tumor deposits located in the extramural fatty tissue are regarded as EX in tumors in which continuous spread is confined within the SM or MP. Tumor deposits located ≥5 mm from the leading edge of the primary tumor are designated as EX for tumors that directly penetrate the MP. |
ND is treated as LNM and each ND is separately counted as a lymph node in the final pN determination. Vascular/perineural invasion lesions are treated as T‐factor, thereby changing the final pT determination (i.e., T3) in tumors that would otherwise be classified as T1 or T2. ND with histological evidence of venous invasion or perineural invasion in the nodule is recorded with a symbol of ND(V+) or ND(Pn+) because it represents a strong likelihood of getting a poor prognosis. |
Abbreviation: EX, extramural cancer deposit without lymph node structure; H&E, hematoxylin and eosin staining; JSCCR, Japanese Society for Cancer of the Colon and Rectum; LNM, lymph node metastasis; MP, muscularis propria; ND(Pn+), tumor nodule with histological evidence of perineural invasion in the nodule; ND(V+), tumor nodule with histological evidence of venous invasion in the nodule; ND, tumor nodule without histological evidence of residual lymph node structure; SM, submucosal layer.