Robert Geraghty

Stage II colonic adenocarcinoma: a detailed study of pT4N0 with emphasis on peritoneal involvement and the role of tumour budding

Canney A L, Kevans D, Wang L M, Hyland J M P, Mulcahy H E, O’Donoghue D P, O’Sullivan J, Geraghty R & Sheahan K 
(2012) Histopathology 61, 488–496

Enrichment of Inflammatory IL-17 and TNF-α Secreting CD4(+) T Cells within Colorectal Tumors despite the Presence of Elevated CD39(+) T Regulatory Cells and Increased Expression of the Immune Checkpoint Molecule, PD-1.

T cell infiltration into colorectal tumors has been shown to correlate with improved patient outcomes. However, more detailed information on the makeup and relationships between the infiltrating T cell subsets is lacking. We therefore correlated the extent of immune infiltration into colorectal tumors with the frequencies of various T cell subsets. We prospectively recruited 22 patients at the time of surgical resection for colorectal cancer. The Klintrup–Mäkinen (KM) score was used to estimate the extent of immune infiltration into colorectal tumors. The frequencies of CD4 and CD8 T cells that produced cytokines or expressed the inhibitory molecule programed cell death 1 (PD-1) were determined by flow cytometry in colorectal tumor and matched uninvolved colonic tissue. In addition, the frequency of CD4 regulatory T cell (Treg) subsets was determined. An increased frequency of CD4 T cells producing IL-17 (Th17 cells) was observed in colorectal tumor tissue compared with adjacent uninvolved tissue. These Th17 cells mostly coproduced TNF-α, but not IFN-γ. IL-17 expression correlated positively with TNF-α and IL-10. Increased expression of the immune checkpoint molecule PD-1 was found in colorectal tumors compared with adjacent uninvolved tissue. There was a negative correlation between expression of PD-1 and IFN-γ, but not IL-17, for both CD4+ and CD8+ T cells. CD4+CD25+CD127lo and CD4+CD25+CD127loFoxP3+CD39+ Treg cells were enriched in colorectal tumors. A positive correlation between KM score and percentage CD4+CD25+CD127lo Treg cells was observed in tumors, suggesting that increased immune infiltration is associated with an increased proportion of Treg cells. In addition, there was a negative correlation between the frequency of CD4+CD25+CD127lo Treg cells and the expression of IFN-γ and IL-2, but not IL-17, in tumors. Taken together, these data suggest that both PD-1 expressing T cells and Treg cells within the tumor may have a suppressive effect on T cells secreting IFN-γ, IL-2, or TNF-α, but not Th17 cells.

Screening for mismatch repair deficiency in colorectal cancer: data from three academic medical centers

Reflex immunohistochemistry (rIHC) for mismatch repair (MMR) protein expression can be used as a screening tool to detect Lynch Syndrome (LS). Increasingly the mismatch repair‐deficient (dMMR) phenotype has therapeutic implications. We investigated the pattern and consequence of testing for dMMR in three Irish Cancer Centres (CCs). CRC databases were analyzed from January 2005–December 2013. CC1 performs IHC upon physician request, CC2 implemented rIHC in November 2008, and CC3 has been performing rIHC since 2004. The number of eligible patients referred to clinical genetic services (CGS), and the number of LS patients per center was determined. 3906 patients were included over a 9‐year period. dMMR CRCs were found in 32/153 (21%) of patients at CC1 and 55/536 (10%) at CC2, accounting for 3% and 5% of the CRC population, respectively. At CC3, 182/1737 patients (10%) had dMMR CRCs (P < 0.001). Additional testing for the BRAF V600E mutation, was performed in 49 patients at CC3 prior to CGS referral, of which 29 were positive and considered sporadic CRC. Referrals to CGS were made in 66%, 33%, and 30% of eligible patients at CC1, CC2, and CC3, respectively. LS accounted for CRC in eight patients (0.8%) at CC1, eight patients (0.7%) at CC2, and 20 patients (1.2%) at CC3. Cascade testing of patients with dMMR CRC was not completed in 56%. Universal screening increases the detection of dMMR tumors and LS kindreds. Successful implementation of this approach requires adequate resources for appropriate downstream management of these patients.

Tumor Budding and PDC Grade are Stage Independent Predictors of Clinical Outcome in Mismatch Repair Deficient Colorectal Cancer

Mismatch repair deficient (dMMR) colorectal cancer (CRC) despite its association with poor histologic grade often has improved prognosis compared with MMR proficient CRC. Tumor budding and poorly differentiated clusters (PDCs) may predict metastatic potential of colorectal adenocarcinoma (CRC). In addition, their assessment may be more reproducible than the evaluation of other histopathologic parameters. Therefore, we wished to determine their potential as prognostic indicators in a cohort of dMMR CRC patients relative to histologic grade. We investigated the predictive value of conventional WHO grade, budding, PDC grade and other histopathologic parameters on the presence of lymph node metastasis (LNM) and clinical outcome in 238 dMMR CRCs. MMR status was determined by immunohistochemistry for the mismatch repair proteins hMLH1, hMSH2, hMSH6, and hPMS2. Tumor budding and PDCs were highly correlated (r=0.701; P<0.000). Both budding and PDC grade were associated with WHO grade, perineural invasion, lympho-vascular invasion, and extramural vascular invasion, and the presence of LNM in dMMR CRC (P<0.009). Independent predictors of LNM were PDC grade (odds ratio, 4.12; 95% confidence interval [CI], 1.69-10.04; P=0.011) and EMVI (odds ratio, 3.81; 95% CI, 1.56-9.19; P<0.000). Only pTstage (hazard ratio [HR], 4.11; 95% CI, 1.48-11.36; P=0.007) and tumor budding (HR, 2.99; 95% CI, 1.72-5.19; P<0.000) were independently associated with worse disease-free survival (DFS). If tumor budding was excluded from the model, PDC grade became significant for DFS (HR, 2.34; 95% CI, 1.34-4.09; P=0.003). WHO Grade does not independently correlate with clinical outcome in dMMR CRC. PDC grade and extramural vascular invasion are independent predictors of LNM. Tumor budding and pTstage are the best predictors of DFS. If tumor budding cannot be assessed, PDC grade may be used as a prognostic surrogate.

Correlation of immunohistochemical mismatch repair protein status between colorectal carcinoma endoscopic biopsy and resection specimens

Background Microsatellite instability is reflective of a deficient mismatch repair system (dMMR), which may be due to either sporadic or germline mutations in the relevant mismatch repair (MMR) gene. MMR status is frequently determined by immunohistochemistry (IHC) for mismatch repair proteins (MMRPs) on colorectal cancer (CRC) resection specimens. However, IHC testing performed on endoscopic biopsy may be as reliable as that performed on surgical resections. Aim We aimed to evaluate the reliability of MMR IHC staining on preoperative CRC endoscopic biopsies compared with matched-surgical resection specimens. Methods A retrospective search of our institution’s histopathology electronic database was performed. Patients with CRC who had MMR IHC performed on both their preoperative endoscopic biopsy and subsequent resection from January 2010 to January 2016 were included. Concordance of MMR staining between biopsy and resection specimens was assessed. Results From 2000 to 2016, 53 patients had MMR IHC performed on both their preoperative colorectal endoscopic biopsy and resection specimens; 10 patients (18.87%) demonstrated loss of ≥1 MMRP on their initial endoscopic tumour biopsy. The remainder (81.13%) showed preservation of staining for all MMRPs. There was complete agreement in MMR IHC status between the preoperative endoscopic biopsies and corresponding resection specimens in all cases (κ=1.000, P<0.000) with a sensitivity of 100% (95% CI 69.15 to 100) and specificity of 100% (95% CI 91.78 to 100) for detection of dMMR. Conclusion Endoscopic biopsies are a suitable source of tissue for MMR IHC analysis. This may provide a number of advantages to both patients and clinicians in the management of CRC.