[683] Retrospective Evaluation of Elastic Stain in the Assessment of Serosal Invasion of pT3N0Mx Colorectal Cancers

Wen Yih Liang, Chih Yi Hsu, Thomas Arnason, Alexander T Hawkins, Patricia Sylla, Gregory Y Lauwers. Veterans General Hospital-Taipei, Taipei, Taiwan; Massachusetts General Hospital, Boston, MA

Background: Peritoneal involvement is an important adverse prognostic factor in colorectal cancer (CRC) and determines a shift in pTNM stage. Peritoneal involvement can be difficult to identify both macroscopically and microscopically. Ancillary studies, such as elastic stains and CK7 immunohistochemical (IHC) stains, have been used to highlight the elastic lamina and peritoneal surface. The aims of this study were to determine whether these stains are useful to refine the level of tumor invasion and determine if restaging based on the results of these stains has prognostic significance in pT3 CRCs.
Design: We retrospectively performed one elastic stain per case on 244 consecutively resected pT3N0Mx CRCs. CK7 IHC was performed in an unselected subset of 169 cases. Associations between peritoneal elastic lamina invasion (ELI) and outcomes (recurrence, metastasis, and survival) were evaluated.
Results: The elastic lamina was identified in only 101 cases (41%), at a frequency of 45% in the cecum/ascending colon, 37% in the transverse, 45% in the descending/sigmoid, and 32% in the rectum. In total, 60 cases (24.6%) displayed ELI. Table 1 shows that peritoneal ELI was associated with a higher rate of recurrence and metastasis (p=0.0001), more disease-related death (p<0.0001) and worse 5-year survival (p=0.001). Mesothelial cells were highlighted by CK7 staining in only 27 cases (16%) and helped demonstrate serosal invasion in only 5 cases (3%).

Table 1
 ELNIELI-ELI+TotalP value
Cases number1434160244 
Recurrent or metastasis9.1%7.3%31.7%14.3%0.0001
Died of Disease4.5%2.4%26.7%9.8%<0.0001
5 year survival85.3%92.7%66.7%82.0%0.001
ELNI:elastic lamina not identified; ELI-/+:elastic laminal invasion absent/present

Conclusions: ELI was detected in 24.6% of pT3 CRCs and was a powerful predictor of adverse outcome compared to patients with tumors lacking ELI. In the elastic lamina not identified cases, the prognostic trend was intermediate, which reflects the expectation that this group would include a few cases where ELI was missed due to inadequate elastic lamina sampling. CK7 IHC was not a sensitive method to indicate peritoneal involvement and was therefore less useful. A single elastic stain is a very useful and inexpensive method to demonstrate peritoneal involvement and should be considered for routine use in all pT3 CRCs. The pT3 tumors with ELI have an adverse prognosis and should be classified separately in a higher stage group than pT3 tumors without evidence of ELI.
Category: Gastrointestinal

Wednesday, March 6, 2013 9:30 AM

Poster Session V # 83, Wednesday Morning


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