ORIGINAL PAPER Heterogeneity of pT3 Colorectal Carcinomas According to the Depth of Invasion Rita Bori & István Sejben & Mihály Svébis & Kornél Vajda & László Markó & Gábor Pajkos & Gábor Cserni Received: 3 August 2008 / Accepted: 8 January 2009 / Published online: 27 January 2009 # Arányi Lajos Foundation 2009 Abstract Colorectal carcinomas (CRCs) infiltrating through the muscularis propria layer without infiltration of adjacent structures, organs or the serosa—i.e. the pT3 tumors, compose the largest subset of large intestinal carcinomas treated by surgical resection. They are hetero- geneous in terms of prognosis. CRCs treated by surgery in a period of 69 months were prospectively classified as pT3a tumors (invading to a maximum of 5 mm beyond the muscularis propria) and pT3b tumors (invading deeper). Their nodal status, incidence of vascular invasion and the presence or absence of distant metastases were analyzed in relation to the depth of invasion. Of the 593 CRCs primarily treated by surgery 429 were pT3 tumors. CRCs categorized as pT3a had significantly lower rates of nodal involvement (44% vs 75%), massive nodal involvement (pN2) (9% vs 39%), venous invasion (17% vs 30%) and distant metastasis (11% vs 28%) than pT3b tumors. Significant differences in these prognostic variables in pT3a and pT3b cancers were observed both for carcinomas of the colon and those of the rectum. Such differences were not obvious in further 66 ypT3 cases of rectal carcinoma receiving neoadjuvant treatment before surgery. Tumors in the pT3a category are associated with a better prognostic profile than pT3b tumors. This subdivision might be useful in both prognostication and treatment planning. Keywords Colorectal carcinoma . TNM . Depth of invasion . Metastasis . Venous invasion Introduction The main prognosticators of colorectal carcinomas include the presence or absence of distant metastasis, the depth of invasion through the anatomic layers of the bowel, regional lymph node involvement and vascular (venous) invasion. The first three of these parameters are included in practically all staging systems [1], including the TNM (tumor-node-metastasis) classification of malignant tumors. [2, 3] The presence of both distant and nodal metastases and also that of venous invasion is related to the depth of invasion which is reflected by the pT category of the TNM classification. [4–7] The presence of nodal metastases is also associated with the presence of distant ones. [8] Most of the cases of colorectal carcinomas treated surgically currently belong to the category of pT3 tumors, i.e. those invading through the muscularis propria, but not crossing the limits of the organ including the peritoneum. The depth of invasion is at least in part a time dependent variable (the disease needs to cross the submucosal and muscularis layers before) and reflects the time span since the tumor was formed. On the other side, it may also be related to tumor aggressivity, as more aggressive tumors are Pathol. Oncol. Res. (2009) 15:527–532 DOI 10.1007/s12253-009-9149-x R. Bori (*) : I. Sejben : G. Cserni Department of Pathology, Bács-Kiskun County Teaching Hospital, Nyíri út 38., 6000 Kecskemét, Hungary e-mail: boririta@hotmail.com M. Svébis Department of Surgery, Bács-Kiskun County Teaching Hospital, Kecskemét, Hungary K. Vajda Department of Surgery, City Hospital, Kiskunfélegyháza, Hungary L. Markó : G. Pajkos Department of Oncology, Bács-Kiskun County Teaching Hospital, Kecskemét, Hungary