Clinical significance of pT sub-classification in surgical pathology of colorectal cancer.
OBJECTIVE
Tumour stage is the strongest prognostic parameter in colorectal cancer. The study aimed to evaluate the prognostic impact of pT2, pT3, and pT4 sub-classification.


METHODS
Three hundred eighty-one surgical colorectal cancer specimens were retrospectively re-evaluated. pT2 tumours were sub-classified according to infiltration of the inner circumferential (pT2a) or outer longitudinal (pT2b) layer of the muscularis propria. pT3 tumours were sub-classified by measuring the maximal tumour invasion beyond the outer border of the muscularis propria (pT3a <or= 1 mm, pT3b > 1-5 mm, pT3c > 5-15 mm, and pT3d > 15 mm). pT4 tumours were sub-classified according to invasion of other organs or structures (pT4a) or perforation of the visceral peritoneum (pT4b). Data were correlated with other pathological parameters and patient outcome.


RESULTS
Seventy pT2 tumours were re-classified as 37 pT2a and 33 pT2b tumours. There was no significant association with tumour grade, angioinvasion, or lymph node involvement and no significant impact on prognosis. Two hundred eighteen pT3 tumours were re-classified as 49 pT3a, 83 pT3b, 53 pT3c, and 33 pT3d tumours. pT3 sub-classification was significantly associated with tumour grade, angioinvasion, and lymph node involvement and proved to be an independent prognostic variable with respect to progression-free and cancer-specific survival. A cut-off level of 5 mm is recommended. Sixty-five pT4 tumours were re-classified as 15 pT4a and 50 pT4b tumours. There was no significant association with tumour grade, angioinvasion, or lymph node involvement and no significant impact on prognosis.


CONCLUSIONS
pT3 sub-classification was significantly associated with patient outcome. In contrast, pT2 and pT4 sub-classification did not show clinical significance.
Pollheimer
Marion J
MJ
Institute of Pathology, Medical University, Auenbruggerplatz 25, 8036 Graz, Austria.
Kornprat
Peter
P
Pollheimer
Verena S
VS
Lindtner
Richard A
RA
Schlemmer
Andrea
A
Rehak
Peter
P
Langner
Cord
C
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002454:Cell Differentiation; D015179:Colorectal Neoplasms / Q000401:mortality / Q000473:pathology* / Q000556:secondary / Q000601:surgery; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D012004:Rectal Neoplasms / Q000401:mortality / Q000473:pathology* / Q000556:secondary / Q000601:surgery; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome