Peritoneal elastic lamina invasion: limitations in its use as a prognostic marker in stage II colorectal cancer.

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 < .001). Right-sided tumors were also associated with a reduction in the staining intensity of the elastic lamina (P < .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.