Isacco Maretto

The Potential of Restaging in the Prediction of Pathologic Response After Preoperative Chemoradiotherapy for Rectal Cancer

BackgroundWe performed this study to prospectively evaluate the postchemoradiotherapy performance of transrectal ultrasonography (TRUS), pelvic computed tomography (CT) scan and magnetic resonance imaging (MRI), and endoscopic biopsies for predicting the pathologic complete response of rectal cancer patients.MethodsFour weeks after completion of preoperative chemoradiotherapy, 46 consecutive patients with mid to low rectal cancer were prospectively evaluated by proctoscopy, TRUS, and pelvic CT scan and MRI. On the basis of T and N status, patients were classified as T0 or T1–4 and N-negative or N-positive. For each staging modality used, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were calculated. Findings were compared with the pathologic tumor-node-metastasis stage.ResultsOn histopathologic analysis, 12 patients had pT0 and 34 had pT1–4 lesions; out of 45 assessable patients, 9 were N-positive. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy in predicting T status (T0 vs. T ≥1) were 77%, 33%, 74%, 36%, and 64%, respectively, for TRUS; 100%, 0%, 74%, not assessable, and 74% for CT; and 100%, 0%, 77%, not assessable, and 77% for MRI. The corresponding figures in predicting N status (N-negative vs. N-positive) were, respectively, 37%, 67%, 21%, 81%, and 61% for TRUS; 78%, 58%, 32%, 91%, and 62% for CT; and 33%, 74%, 25%, 81%, and 65% for MRI.ConclusionsCurrent rectal cancer staging modalities after chemoradiotherapy allow good prediction of node-negative cases, although none of them is able to predict the pathologic complete response on the rectal wall.

Local excision after preoperative chemoradiotherapy for rectal cancer: results of a multicenter phase II clinical trial.

BACKGROUND: Transanal local excision has been suggested as an attractive approach for patients with rectal cancer who show a major clinical response after preoperative chemoradiotherapy. OBJECTIVE: To evaluate the impact of transanal local excision on the local recurrence of rectal cancer in patients who had a major clinical response after preoperative chemoradiotherapy. DESIGN: Sequential 2-stage phase II study for early efficacy. SETTING: Multicenter study. PATIENTS: Patients with clinical T3 or low-lying T2 rectal adenocarcinoma that showed a major clinical response after a preoperative chemoradiotherapy. Eligible patients underwent a full-thickness transanal local excision. According to their histopathology, the patients staged as ypT0-1 were observed, while the remaining patients were recommended to undergo a subsequent total mesorectal excision. MAIN OUTCOME MEASURES: A local recurrence rate of ⩽5% was set as a successful rate for stopping the trial early after the first stage. RESULTS: The study group included 63 patients. Before chemoradiotherapy, patients were staged as clinical T3 (n = 42) and T2 (n = 21). After the local excision, 43 patients fulfilled the criteria to be observed with no further treatment. Nine of the remaining 20 patients for whom a subsequent total mesorectal excision was recommended refused surgery. Two of these patients who refused surgery had intraluminal local recurrence; both had a ypT2 tumor and underwent salvage surgery. The estimated cumulative 3-year overall survival, disease-free survival and local disease-free survival were 91.5% (95% CI: 75.9–97.2), 91.0% (95% CI: 77.0–96.6) and 96.9% (95% CI: 80.3–99.5), respectively. LIMITATIONS: The time of follow-up is still short and the sample size is limited. CONCLUSIONS: Our data suggest that local excision is a good option for patients with a major clinical response after chemoradiotherapy. A longer period of follow-up is required to confirm these findings.

Prospective assessment of imaging after preoperative chemoradiotherapy for rectal cancer.

BACKGROUND The aim of the study was to assess the accuracy of imaging techniques in predicting pathologic tumor (ypT), node (ypN) stages and the circumferential resection margin (ypCRM) status of rectal cancers after preoperative chemoradiotherapy (CRT). METHODS Using pelvic computed tomography (CT), magnetic resonance imaging (MRI), and endorectal ultrasound (ERUS), 90 consecutive patients with locally advanced mid-to-low rectal cancer were prospectively assessed. Postirradiation T and N stages and infiltration of the CRM, as assessed by CT, MRI and ERUS, were compared with histopathologic findings. RESULTS The accuracy of ypT staging was low, whatever the imaging technique used (37% by CT, 34% by MRI, and 27% by ERUS), the most frequent inaccuracy being overstaging. Imaging showed a good specificity and good negative predictive values (NPV) when mural staging was grouped into ypT ≤ 3 and ypT4 categories; in particular, ERUS achieved a 92% specificity and 95% NPV. CRM involvement was correctly predicted in 71% of patients by CT (74% specificity; 93% NPV) and in 85% by MRI (88% specificity; 95% NPV). The accuracy for nodal staging was 62%, 68%, and 65% by CT, MRI and ERUS, respectively; the corresponding NPV were 88%, 78%, and 76%. CONCLUSION Current imaging techniques are inaccurate in restaging rectal cancer after CRT but are useful in predicting T ≤ 3 tumors, cases with negative nodes and tumor-free CRM. These findings may be of clinical relevance for planning less invasive surgery.

Telomerase is an independent prognostic marker of overall survival in patients with colorectal cancer.

Background:Colorectal cancer (CRC) is an important cause of cancer-related death. Prediction of recurrence is an important issue in the treatment of disease, particularly for stage II patients. The level of telomere-specific reverse transcriptase (hTERT), the catalytic component of the telomerase complex, increases along with CRC progression, but its prognostic value is still unclear.Methods:One hundred and thirty-seven CRC patients were studied for hTERT expression in tumour cells by real-time PCR. hTERT level was evaluated as a prognostic factor of overall survival (OS) in all patients and of disease recurrence in a subgroup of 50 stage II patients.Results:The median hTERT level was 93.8 copies (interquartile range 48–254). Patients with high hTERT levels (above the median) showed a significantly worse survival than those with low hTERT levels (below the median; log-rank test P<0.0001; hazard ratio (HR)=3.30 (95% confidence interval (CI) 1.98–5.52); P<0.0001). The negative prognostic value of high hTERT level is independent of the pathological stage and microsatellite instability (HR=2.09 (95% CI 1.20–3.64), P=0.009). Moreover, in stage II CRC, high hTERT levels identified patients with a higher risk of disease recurrence (HR=3.06 (95% CI 1.03–9.04), P=0.043) and death (HR=3.24 (95% CI 1.37–7.71), P=0.008).Conclusion:hTERT level is an independent prognostic marker of OS in CRC patients. In addition, assessment of hTERT level could improve stratification of stage II CRC patients for the risk of disease recurrence.

The role of MYH gene in genetic predisposition to colorectal cancer: Another piece of the puzzle

Biallelic germline mutations in the MYH gene cause MYH-Associated Polyposis but patients with a single mutation possibly have an increased colorectal cancer (CRC) risk. Using DNA from consecutive CRC patients we carried out a case-control study, with the aim to contribute data on the Italian population. Genotyping of four MYH mutations found two biallelic and two monoallelic carriers among 439 cases, and only one heterozygous individual among 247 age-matched controls. The frequencies of the mutant alleles were 0.68% (6/878) and 0.20% (1/494), respectively. These differences were not statistically significant. Results on the monoallelic carriers were combined with those from 11 studies on other populations, and the risk of developing a CRC was estimated with an OR=1.11 (95% CI=0.90; 1.36), yet not reaching a significant evidence of increased CRC risk.

Prediction of rectal lymph node metastasis by pelvic computed tomography measurement

AIM Rectal cancer staging represents a crucial step to select the best treatment for this tumour. Particularly after neo-adjuvant chemoradiotherapy (CRT), it may influence the surgical procedure (e.g. radical resection vs. local excision). The aim of this study was to determine the best lymph node size cut-off at computed tomography (CT) to predict nodal metastasis in rectal cancer patients with and without preoperative CRT. METHODS A consecutive series of patients operated on for primary mid-low rectal adenocarcinoma, all staged with pelvic CT scan, were subdivided as follows: those who underwent surgery alone treatment without CRT (Group A) and those who underwent preoperative CRT (Group B). All CT scans were re-viewed by a single radiologist and, based on the lymph node size, findings were compared with pathologic lymph node status (pN). At each lymph node size cut-off value, the following were calculated: accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV). The best cut-off value was defined as having an accuracy >or=70% with the highest NPV. RESULTS The study population consisted of 162 patients: Group A (n=52) and Group B (n=110). Patients classified as pN-positive (n=45) had a higher number of and larger sized lymph nodes by CT scan than patients classified as pN-negative (n=117). The cut-off values with an accuracy >or=70% ranged between 7 and 11 mm in Group A and between 9 and 14 mm in Group B. The cut-off with the best NPV was 7 mm for Group A and 10mm for Group B. CONCLUSIONS Acknowledging the limitations of the dimensional criterion, lymph node size cut-off values found in our study may be useful for planning rectal cancer treatment using CT scan.

A functional biological network centered on XRCC3: A new possible marker of chemoradiotherapy resistance in rectal cancer patients

Preoperative chemoradiotherapy is widely used to improve local control of disease, sphincter preservation and to improve survival in patients with locally advanced rectal cancer. Patients enrolled in the present study underwent preoperative chemoradiotherapy, followed by surgical excision. Response to chemoradiotherapy was evaluated according to Mandards Tumor Regression Grade (TRG). TRG 3, 4 and 5 were considered as partial or no response while TRG 1 and 2 as complete response. From pretherapeutic biopsies of 84 locally advanced rectal carcinomas available for the analysis, only 42 of them showed 70% cancer cellularity at least. By determining gene expression profiles, responders and non-responders showed significantly different expression levels for 19 genes (P < 0.001). We fitted a logistic model selected with a stepwise procedure optimizing the Akaike Information Criterion (AIC) and then validated by means of leave one out cross validation (LOOCV, accuracy = 95%). Four genes were retained in the achieved model: ZNF160, XRCC3, HFM1 and ASXL2. Real time PCR confirmed that XRCC3 is overexpressed in responders group and HFM1 and ASXL2 showed a positive trend. In vitro test on colon cancer resistant/susceptible to chemoradioterapy cells, finally prove that XRCC3 deregulation is extensively involved in the chemoresistance mechanisms. Protein-protein interactions (PPI) analysis involving the predictive classifier revealed a network of 45 interacting nodes (proteins) with TRAF6 gene playing a keystone role in the network. The present study confirmed the possibility that gene expression profiling combined with integrative computational biology is useful to predict complete responses to preoperative chemoradiotherapy in patients with advanced rectal cancer.

Predictive response biomarkers in rectal cancer neoadjuvant treatment

Locally advanced rectal cancer (RC) treatment is a challenge, because RC has a high rate of local recurrence. To date preoperative chemoradiotherapy (pCRT) is widely accepted as standard protocol of care for middle-low RC, but complete tumour response rate ranges from 4 to 44% and 5-year local recurrence rate is 6%. Better understanding of molecular biology and carcinogenesis pathways could be used both for pre-neoplastic lesions and locally recurrence diagnosis, and for tumour response prediction to therapy. Circulating molecules, gene expression and protein signature are promising sources to biomarker discovery. Several studies have evaluated potential predictors of response and recently, cell-free Nucleic Acid levels have been associated to tumour response to neoadjuvant therapies. Alternative method is the serum or plasma proteome and peptidome analysis. It may be ideally suited for its minimal invasiveness and it can be repeated at multiple time points throughout the treatment in contrast to tissue-based methods which still remain the most reliable and specific approach. Many studies have analyzed preoperative rectal tissue prognostic factor, but data are controversial or not confirmed.

Serum miR-125b is a non-invasive predictive biomarker of the pre-operative chemoradiotherapy responsiveness in patients with rectal adenocarcinoma

Background Therapeutic management of Locally Advanced Rectal Cancer (LARC) involves pre-operative chemoradiotherapy (pCRT) followed by surgery. However, after pCRT the complete pathological response is approximately 20%, whereas in 20 to 40% of patients the response is poor or absent. Methods Cancer biopsy specimens (n= 38) and serum samples (n= 34) obtained before pCRT from 38 LARC patients were included in the study. Patients were classified in responders (R, tumor regression grade [TRG] 1-2; n= 16) and non-responders (NR, TRG 3-5; n= 22) according to the pathological response observed upon surgery. We performed miRNA microarrays analysis on biopsy specimens, and validated the selected candidates both by qRT-PCR (tissue and serum) and by in situ hybridization (tissue, miR-125b) analyses. Results Eleven miRNAs were significantly different between R and NR (miR-154, miR-409-3p, miR-127-3p, miR-214*, miR-299-5p and miR-125b overexpressed in NR; miR-33a, miR-30e, miR-338-3p, miR-200a and miR-378 decreased). In particular, miR-125b resulted to be the best candidate to discriminate the two groups (AUC of 0.9026; 95% CI, 0.7618-1.043). Additionally, miR-125b serum levels were significantly overexpressed in NR patients compared to R (p-value=0.0087), with an excellent discriminating power (AUC of 0.782; 95% CI, 0.6123-0.9518). Conclusions The obtained results further support the clinical impact of miRNA analysis. High miR-125b expression in tissue and serum were associated with a poor treatment response in LARC patients, therefore miR-125b could be considered as a possible novel non-invasive biomarker of response in LARC treatment.

Gene and microRNA Expression Are Predictive of Tumor Response in Rectal Adenocarcinoma Patients Treated with Preoperative Chemoradiotherapy

Preoperative chemoradiotherapy (pCRT) followed by surgery is the standard treatment for locally advanced rectal cancer (LARC). However, tumor response to pCRT is not uniform, and there are no effective predictive methods. This study investigated whether specific gene and miRNA expression are associated with tumor response to pCRT. Tissue biopsies were obtained from patients before pCRT and resection. Gene and miRNA expression were analyzed using a one‐color microarray technique that compares signatures between responders (R) and non‐responders (NR), as measured based on tumor regression grade. Two groups composed of 38 “exploration cohort” and 21 “validation cohort” LARC patients were considered for a total of 32 NR and 27 R patients. In the first cohort, using SAM Two Class analysis, 256 genes and 29 miRNAs that were differentially expressed between the NR and R patients were identified. The anti‐correlation analysis showed that the same 8 miRNA interacted with different networks of transcripts. The miR‐630 appeared only with the NR patients and was anti‐correlated with a single transcript: RAB5B. After PAM, the following eight transcripts were strong predictors of tumor response: TMEM188, ITGA2, NRG, TRAM1, BCL2L13, MYO1B, KLF7, and GTSE1. Using this gene set, an unsupervised cluster analysis was applied to the validation cohort and correctly assigned the patients to the NR or R group with 85.7% accuracy, 90% sensitivity, and 82% specificity. All three parameters reached 100% when both cohorts were considered together. In conclusion, gene and miRNA expression profiles may be helpful for predicting response to pCRT in LARC patients. J. Cell. Physiol. 232: 426–435, 2017.