TNM staging system of colorectal carcinoma: a critical appraisal of challenging issues.
BACKGROUND
Colorectal cancer is the leading cause of morbidity and death among gastrointestinal tumors and ranks fourth after lung, breast, and ovarian cancers. Despite a continuous refinement of the T (tumor), N (node), and M (metastasis) staging system to express disease extent and define prognosis, and eventually to guide treatment, the outcome of patients with colorectal cancer may vary considerably even within the same tumor stage. Therefore, the need for new factors, either morphologic or molecular, that could more precisely stratify patients into different risk categories is clearly warranted.


OBJECTIVE
To present the state of the art with regard to the colorectal cancer staging system and to discuss confusing and/or challenging issues, including the assessment of peritoneal membrane involvement, vascular invasion, tumor deposits, and pathologic tumor response to neoadjuvant chemoradiotherapy.


METHODS
Literature review of relevant articles indexed in PubMed (US National Library of Medicine) and primary material from the authors' institutions.


CONCLUSIONS
Two emerging needs exist for the TNM system, namely, further stratification of patients with the same tumor stage and incorporation of nonanatomic factors, the latter including molecular and treatment factors. The identification and classification of morphologic features encountered in the pathologic examination of colorectal cancer specimens may be difficult and a source of subjective variability. Enhanced pathologic analysis, agreed-upon standard protocols, and standardization should improve the completeness and accuracy of pathology reports.
Puppa
Giacomo
G
Division of Pathology, G. Fracastoro City Hospital, Verona, Italy. gpuppa@yahoo.com
Sonzogni
Angelica
A
Colombari
Romano
R
Pelosi
Giuseppe
G
D000970:Antineoplastic Agents / Q000627:therapeutic use; D015179:Colorectal Neoplasms / Q000098:blood supply / Q000188:drug therapy / Q000473:pathology*; D006801:Humans; D009367:Neoplasm Staging / Q000379:methods / Q000639:trends*; D009389:Neovascularization, Pathologic / Q000473:pathology; D010537:Peritoneum / Q000473:pathology; D016896:Treatment Outcome
D000970:Antineoplastic Agents