Original contribution Peritoneal elastic lamina invasion: limitations in its use as a prognostic marker in stage II colorectal cancer ☆ Andrea Grin MD a,b , David E. Messenger MBChB c,d , Megan Cook MSc e , Brenda I. O'Connor BScN c,d , Sara Hafezi MD b,f , Hala El-Zimaity MD b,f , Richard Kirsch MBChB, PhD b,e, ⁎ a Department of Laboratory Medicine, St Michael's Hospital, Toronto, Canada M5B 1W8 b Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Canada M5S 1A5 c Zane Cohen Clinical Research Centre, Mount Sinai Hospital, Toronto, Canada M5G 1X5 d Division of General Surgery, Mount Sinai Hospital, Toronto, Canada M5G 1X5 e Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, Toronto, Canada M5G 1X5 f Department of Pathology, University Health Network, Toronto, Canada M5G 2C4 Received 13 May 2013; revised 10 July 2013; accepted 12 July 2013 Keywords: Colorectal cancer; Stage II; Elastic lamina invasion; Peritoneal involvement; Prognosis Summary Peritoneal involvement in colorectal cancer (CRC) is an adverse prognostic feature, which may prompt consideration of adjuvant chemotherapy in stage II disease. Controversies and challenges surrounding its assessment have led to consideration of peritoneal elastic lamina invasion (ELI) as an alternative marker of advanced local spread. The objectives of this study were (1) to evaluate the prognostic significance of peritoneal ELI in stage II CRC and (2) to determine the feasibility of ELI assessment in routine practice with the use of an elastic stain. Two hundred seventeen patients with stage II CRC (186, pT3; 31, pT4) were assessed for ELI and other established adverse histologic features. Of the pT3 tumors, 31 (16.7%) were ELI positive, 121 (65%) were ELI negative, and 34 (18.3%) lacked an identifiable elastic lamina. There were no significant differences in disease-free survival between pT3 ELI-negative and ELI-positive tumors (P = .517). The disease-free survival of pT4 tumors was significantly lower than that of pT3 ELI-negative tumors (P = .024) and pT3 ELI- positive tumors (P = .026), respectively. The elastic lamina was detected less frequently in right-sided pT3 tumors compared with left-sided tumors (65/91 [71.4%] versus 87/95 [91.6%], P b .001). Right- sided tumors were also associated with a reduction in the staining intensity of the elastic lamina (P b .001). In conclusion, peritoneal ELI was not an adverse prognostic factor in this study. The frequent absence of an identifiable elastic lamina, particularly in right-sided tumors, may limit the use of ELI as a prognostic marker in CRC. © 2013 Elsevier Inc. All rights reserved. 1. Introduction Prognosis after resection of colorectal cancer is deter- mined by the clinicopathologic stage. Although adjuvant therapy is typically recommended for patients with stage III ☆ Conflict of interest and funding disclosures: None. ⁎ Corresponding author. Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, 600 University Avenue, Toronto, ON, Canada M5G 1X5. E-mail address: rkirsch@mtsinai.on.ca (R. Kirsch). www.elsevier.com/locate/humpath 0046-8177/$ – see front matter © 2013 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.humpath.2013.07.013 Human Pathology (2013) 44, 2696–2705