Pathological and molecular predictors of the response of rectal cancer to neoadjuvant radiochemotherapy

P53 status as a predictive biomarker for patients receiving neoadjuvant radiation-based treatment: a meta-analysis in rectal cancer

Background

Numerous studies have yielded inconsistent results regarding the relationship between p53 status and the response to neoadjuvant radiation-based therapy in patients with rectal cancer. We conducted a meta-analysis to clarify the relationship between p53 status and response to radiation-based therapy in rectal cancer.

Methods/Findings

A total of 30 previously published eligible studies including 1,830 cases were identified and included in this meta-analysis. Wild-type form of p53 status (low expression of p53 protein and/or wild-type p53 gene) was associated with pathologic response in rectal cancer patients who received neoadjuvant radiation-based therapy (good response: risk ratio [RR] = 1.30; 95% confidence intervals [CI] = 1.14–1.49; p<0.001; complete response RR = 1.65; 95% CI = 1.19–2.30; p = 0.003; poor response RR = 0.85; 95% CI = 0.75–0.96; p = 0.007). In further stratified analyses, this association remained for sub-groups of good and poor response in neoadjuvant radiotherapy (RT) setting, good and complete response in chemoradiotherapy (CRT) setting. And the association between response and the presence of p53 gene mutations was stronger than that between response and protein positivity.

Conclusion

The results of the present meta-analysis indicate that P53 status is a predictive factor for response in rectal cancer patient undergoing neoadjuvant radiation-based therapy.

An update on preoperative radiotherapy for locally advanced rectal cancer

Even in patients undergoing an optimal surgical technique (e.g., total mesorectal excision), radiotherapy provides a significant benefit in the local control of rectal cancer. Compared with postoperative treatment, chemoradiotherapy given preoperatively has been shown to decrease local recurrence rates and toxicity. Additionally, preoperative chemoradiotherapy permits the early identification of tumor responses to this cytotoxic treatment by surgical pathology. Pathological parameters reflecting the tumor response to chemoradiotherapy have been shown to be surrogate markers for long-term clinical outcomes. Post-chemoradiotherapy downstaging from cStage II-III to ypStage 0-I indicates a favorable prognosis, with no difference between ypStage 0 and ypStage I. Research is ongoing to develop useful tools (clinical, molecular, and radiological) for clinical determination of the pathologic chemoradiotherapeutic response before surgery, and possibly even before preoperative treatment. In the future, risk-adapted strategies, including intensification of preoperative therapy, conservative surgery, or the selective administration of postoperative chemotherapy, will be realized for locally-advanced rectal cancer patients based on their response to preoperative chemoradiotherapy.

Prediction in rectal cancer

The treatment of rectal cancer largely depends on disease stage at diagnosis, based on which patients can be classified as low, intermediate, or high risk. Prognostic and predictive markers, specific to each risk category, can be applied for optimal risk classification and subsequent treatment allocation. These markers are either histopathological, determined with imaging, or have a biomolecular background. This review provides an overview of the current status of treatment options and the use of prognostic and predictive markers in each risk category. An effort was made to identify those markers that are currently lacking in, but have the potential to improve, the clinical decision process by discussing the data from recent studies aimed at the development of new prognostic and predictive markers. At this moment, none of the markers studied has been proven to be of significant, independent value, justifying implementation in daily clinical practice. However, recent developments in imaging techniques and biomolecular research do show great potential.

Meta-analysis of histopathological features of primary colorectal cancers that predict lymph node metastases

BACKGROUND

Treatment decisions for colorectal cancer vary based on lymph node status. While some histopathological features of the primary tumor correlate with lymph node spread, the relative influences of these risk factors are not well quantified.

OBJECTIVE

This study aims to systematically review published studies relating histopathological features of primary colorectal cancer to the presence of lymph node metastases and to determine how reliable certain factors might be at predicting nodal metastasis when only the primary lesion is available for study.

DATA SOURCES

Inclusive literature search using EMBASE and Ovid MEDLINE databases plus manual reference checks of all articles correlating lymphatic spread with colorectal cancer (any T stage) from 1984 to mid-2008 was performed.

STUDY SELECTION

This search generated two levels of screening utilized on 602 citations, yielding 123 articles for full review. Data reported from 76 articles were chosen.

MAIN OUTCOME MEASURES

The relative influence of each histopathological feature on the likelihood of lymphatic metastases was determined. Fixed-effects meta-analysis was performed, and results were reported as Mantel-Haenszel odds ratios (OR).

RESULTS

Of 42 histopathological features analyzed, only 40.4% were reported in >2 articles. The positive predictive values for the top quartile of most frequently reported risk factors were 25.5-86.4%. Among the commonly reported histopathological findings, lymphatic invasion (OR, 8.62) significantly outperformed tumor depth (T2 vs. T1; OR, 2.62) and overall differentiation (OR, 2.38) in predicting nodal spread. For the rectal cancer subset, risk factors differed from the overall colorectal group in predictive ability; poor differentiation at the invasive front (OR, 6.08) and tumor budding (OR, 5.82) were the most predictive.

LIMITATIONS

This literature search is limited by the small number of studies examining only rectal cancers and the potential changes in histological and/or surgical techniques over the study period.

CONCLUSIONS

No single histopathological feature of colorectal cancer reliably predicted lymph node metastases. Several risk factors that correlate highly with nodal disease are not routine components of standard pathology reports. Until further research establishes histopathological or molecular patterns for predicting lymph node spread, caution should be exercised when basing treatment decisions solely on these factors.

The surgical significance of residual mucosal abnormalities in rectal cancer following neoadjuvant chemoradiotherapy

BACKGROUND

Local excision of rectal cancer after neoadjuvant chemoradiotherapy (CRT) has been proposed as an alternative to radical surgery in selected patients. However, little is known about the significance of the morphological and histological features of residual tumour.

METHODS

Patients who had undergone CRT at the authors' institution between 1997 and 2010 were identified. Multiple features were assessed as putative markers of pathological response. These included: gross residual disease, diameter of residual mucosal abnormalities, tumour differentiation, presence of lymphovascular/perineural invasion and lymph node ratio.

RESULTS

Data from 220 of 276 patients were suitable for analysis. Diameter of residual mucosal abnormalities correlated strongly with pathological tumour category after CRT (ypT) (P < 0·001). Forty of 42 tumours downstaged to ypT0/1 had residual mucosal abnormalities of 2·99 cm or less after CRT. Importantly, 19 of 31 patients with a complete pathological response had evidence of a residual mucosal abnormality consistent with an incomplete clinical response. The ypT category was associated with both pathological node status after CRT (P < 0·001) and lymph node ratio (P < 0·001). Positive nodes were found in only one of 42 patients downstaged to ypT0/1. The risk of nodal metastases was associated with poor differentiation (P = 0·027) and lymphovascular invasion (P < 0·001).

CONCLUSION

In this series, the majority of patients with a complete pathological response did not have a complete clinical response. In tumours downstaged to ypT0/1 after CRT, residual mucosal abnormalities were predominantly small and had a 2 per cent risk of positive nodes, thus potentially facilitating transanal excision. The presence of adverse histological characteristics risk stratified tumours for nodal metastases.

Response prediction in the multimodality therapy of locally advanced rectal cancer

SUMMARY Neoadjuvant therapies have been established in the multimodality treatment of locally advanced rectal cancer. Radiation with concurrent 5-fluorouracil-based chemotherapy followed by surgical resection is considered to be the standard of care in advanced rectal cancer. However, recent studies revealed that patients with complete histopathologic response seem to benefit most from neoadjuvant therapies. Consequently, predictive markers to allow individualization of multimodality therapy in locally advanced rectal cancer are mostly required to identify those who will benefit the most. Unfortunately, there is still an immense lack of factors for response assessment in patients with rectal cancer undergoing multimodality treatment. While conventional diagnostic tools lack sufficient accuracy to provide information for response assessment, newer techniques such as [18F]-fluorodeoxyglucose-PET and diffusion-weighted MRI show promising results. In addition, studies on molecular factors for response assessment in rectal cancer are encouraging but still do not provide a reliable instrument for utilization in clinical practice.

Apoptotic proteins as prognostic markers and indicators of radiochemosensitivity in stage II/III rectal cancers

AIM

The expression of pro-apoptotic (Bax) and anti-apoptotic (mutated p53, Bcl-2, Bclxl) proteins was determined retrospectively using immunohistochemistry in pre-treatment biopsy samples from patients with rectal cancer treated with or without preoperative chemoradiation to investigate their role as prognostic markers and indicators of radiochemosensitivity.

METHOD

Biopsy samples from 67 patients operated for stage II/III rectal cancer and enrolled in an active follow-up programme were examined 8-10 years after surgery. Thirty-three had been treated with immediate surgery followed, in selected cases, by adjuvant postoperative chemoradiation. Thirty-four had preoperative chemoradiation. Immunohistochemical staining was carried out using an automated immunostainer on sections of paraffin-embedded tissue.

RESULTS

Independent prognostic factors for rectal cancer death were pN status (hazard ratio 3.82; 95% CI 1.67-8.73) and a high level of Bclxl positivity (hazard ratio 4.75; 95% CI 2.10-10.72) according to multivariate regression analysis by stepwise selection. Bax expression was associated with downstaging and higher survival in irradiated patients (P = 0.0004).

CONCLUSION

Pretreatment evaluation of apoptotic Bax and anti-apoptotic Bclxl factors in biopsy samples of stage II/III rectal cancers may be helpful in selecting tumours that will respond to chemoradiation or in identifying patients who will have limited benefit from chemoradiation and should therefore be selected for a more aggressive systemic regimen.

[Locally advanced rectal cancer management: which role for the pathologist in 2011?]

Locally advanced rectal cancers mainly correspond to lieberkünhien adenocarcinomas and are defined by T3-T4 lesions with or without regional metastatic lymph nodes. Such tumors benefit from neoadjuvant treatment combining chemotherapy and radiotherapy, followed by surgery with total mesorectum excision. Such a strategy can decrease the rate of local relapse and lead to an easier complementary surgery. The pathologist plays an important role in the management of locally advanced rectal cancer. Indeed, he is involved in the gross examination of the mesorectum excision quality and in the exhaustive sampling of the most informative areas. He also has to perform a precise histopathological analysis, including the determination of the circumferential margin or clearance and the evaluation of tumor regression. All these parameters are major prognostic factors which have to be clearly included in the pathology report. Moreover, the next challenge for the pathologist will be to determine and validate new prognostic and predictive markers, notably by using pre-therapeutic biopsies. The goal of this mini-review is to emphasize the pathologist's role in the different steps of the management of locally advanced rectal cancers and to underline its implication in the determination of potential biomarkers of aggressiveness and response.

Can mesorectal lymph node excision be avoided in rectal cancer surgery?

Rectal excision is the standard in rectal cancer treatment. The morbidity of rectal excision, together with the low rate of positive lymph nodes in patients with a good response after radiochemotherapy, raises the challenging concept of organ preservation. Patients with a complete response can benefit from a nonoperative strategy based on a strict follow up. Those with a complete or subcomplete response can be treated by local excision. Limitations in accurately assessing a complete response by conventional and modern imaging modalities suggest that local excision is more appropriate for the majority of patients when organ preservation is being considered. The encouraging results of retrospective series of local excision in downstaged clinical T2/T3 low rectal cancer after radiochemotherapy, however, need to be confirmed by the ongoing multicentre phase II United States and phase III French trials before routinely proposing organ preservation in patients with a good response.

Identification of a biomarker profile associated with resistance to neoadjuvant chemoradiation therapy in rectal cancer

OBJECTIVE

To identify a biomarker profile associated with tumor response to chemoradiation (CRT) in locally advanced rectal cancer.

BACKGROUND

Rectal cancer response to neoadjuvant CRT is variable. Whereas some patients have a minimal response, others achieve a pathologic complete response (pCR) and have no viable cancer cells in their surgical specimens. Identifying biomarkers of response will help select patients more likely to benefit from CRT.

METHODS

This study includes 132 patients with locally advanced rectal cancer treated with neoadjuvant CRT followed by surgery. Tumor DNA from pretreatment tumor biopsies and control DNA from paired normal surgical specimens was screened for mutations and polymorphisms in 23 genes. Genetic biomarkers were correlated with tumor response to CRT (pCR vs non-pCR), and the association of single or combined biomarkers with tumor response was determined.

RESULTS

Thirty-three of 132 (25%) patients achieved a pCR and 99 (75%) patients had non-pCR. Three individual markers were associated with non-pCR; v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog mutation (P = 0.0145), cyclin D1 G870A (AA) polymorphism (P = 0.0138), and methylenetetrahydrofolate reductase (NAD(P)H) C677T (TT) polymorphism (P = 0.0120). Analysis of biomarker combinations revealed that none of the 27 patients with both tumor protein p53 (p53) and v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog mutations had a pCR. Further, in patients with both p53 and v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog mutations or the cyclin D1 G870A (AA) polymorphism or the methylenetetrahydrofolate reductase (NAD(P)H) C677T (TT) polymorphism (n = 52) the association with non-pCR was further strengthened; 51 of 52 (98%) of patients were non-pCR. These biomarker combinations had a validity of more than 70% and a positive predictive value of 97% to 100%, predicting that patients harboring these mutation/polymorphism profiles will not achieve a pCR.

CONCLUSIONS

A specific biomarker profile is strongly associated with non-pCR to CRT and could be used to select optimal oncologic therapy in rectal cancer patients. ClinicalTrials.org Identifier: NCT00335816.

Chromosomal copy number alterations are associated with tumor response to chemoradiation in locally advanced rectal cancer

Rectal cancer response to chemoradiation (CRT) varies from no response to a pathologic complete response (pCR). Identifying predictive biomarkers of response would therefore be useful. We assessed whether chromosomal copy number alterations (CNAs) can assist in predicting pCR. Pretreatment tumor biopsies and paired normal surgical tissues from the proximal resection margin were collected from 95 rectal cancer patients treated with preoperative CRT and total mesorectal excision in a prospective Phase II study. Tumor and control DNA were extracted, and oligonucleotide array-based comparative genomic hybridization (aCGH) was used to identify CNAs, which were correlated with pCR. Ingenuity pathway analysis (IPA) was then used to identify functionally relevant genes in aberrant regions. Finally, a predictive model for pCR was built using support vector machine (SVM), and leave-one-out cross validation assessed the accuracy of aCGH. Chromosomal regions most commonly affected by gains were 20q11.21-q13.33, 13q11.32-23, 7p22.3-p22.2, and 8q23.3-q24.3, and losses were present at 18q11.32-q23, 17p13.3-q11.1, 10q23.1, and 4q32.1-q32.3. The 25 (26%) patients who achieved a pCR had significantly fewer high copy gains overall than non-pCR patients (P = 0.01). Loss of chromosomal region 15q11.1-q26.3 was significantly associated with non-pCR (P < 0.00002; Q-bound < 0.0391), while loss of 12p13.31 was significantly associated with pCR (P < 0.0003; Q-bound < 0.097). IPA identified eight genes in the imbalanced chromosomal regions that associated with tumor response. SVM identified 58 probes that predict pCR with 76% sensitivity, 97% specificity, and positive and negative predictive values of 91% and 92%. Our data indicate that chromosomal CNAs can help identify rectal cancer patients more likely to develop a pCR to CRT.

Immunohistochemical analysis of tumour regression grade for rectal cancer after neoadjuvant chemoradiotherapy

AIM

Tumour regression grade (TRG) as defined by Rödel et al. has been used as an independent prognostic factor for rectal carcinoma after preoperative treatment by chemoradiotherapy (CRT). Determination of TRG 2 and 3, semiquantitatively defined as more or less than 50% tumour regression, respectively, does not appear to correlate with prognosis. The purpose of this study was to find an immunohistochemical pattern to permit improved stratification of intermediate responders defined by disease free (DFS) and overall survival (OS).

METHOD

Immunohistochemistry of EGFR (epidermal growth factor receptor), VEGF (vascular endothelial growth factor), CD133 antibody, p53 antibody and Ki67 antibody was evaluated using tissue microarrays (TMA) on post-treatment surgical specimens from 88 patients. CD133 expression was confirmed in the whole section when available.

RESULTS

At a median follow-up of 40 months, TRG was found to be an independent predictor of DFS (P = 0.05) and OS (P = 0.001) but no differences were found between TRG 2 and 3 in terms of DFS (P = 0.74) or OS (P = 0.41). The results of TMA showed an immunohistochemically poor prognostic profile for intermediate responders configured by negativity of CD133 expression. However, when examining CD133 expression in the whole section, there was an intermediate correlation with TMA and the prognostic significance was lost.

CONCLUSION

The results did not confirm the value of immunohistochemistry in predicting the prognosis of patients with rectal cancer following neoadjuvant chemoradiotherapy. This questions the accuracy of TMA in detecting CD133 expression in this setting.

Serum biomarkers which correlate with failure to respond to immunotherapy and tumor progression in a murine colorectal cancer model

PURPOSE

To advance our understanding of mechanisms involved in tumor progression/regression, a CT26 colorectal mouse model treated intra-tumorally with DISC-herpes simplex virus as immunotherapy was used in the discovery and validation phases to investigate and ultimately identify biomarkers correlating with the failure to respond to immunotherapy.

EXPERIMENTAL DESIGN

For the discovery phase, serum protein/peptide profiles of a retrospective sample collection (total n=70) were analyzed using MALDI-TOF-MS combined with artificial neural networks. Following identification of the key predictive peptides using ESI-MS/MS, validation of the identified proteins was carried out on serum and tissues collected in an independent sample set (total n=60).

RESULTS

Artificial neural network analysis resulted in four discriminatory peaks with an accuracy of 86%, sensitivity of 90% and specificity of 81% between the progressor/regressor groups. Three of the identified discriminatory markers were upregulated and demonstrated a positive correlation with tumor progression following DISC-herpes simplex virus therapy. Immunovalidation studies corroborated the MALDI-TOF-MS findings. Immunohistochemistry revealed that serum amyloid A-1 and serum amyloid P produced in the liver localized intracellularly in CT26 tumor tissue.

CONCLUSIONS

MALDI-TOF-MS and BI analysis of the serum proteome of tumor-bearer mice undergoing immunotherapy, identified biomarkers associating with "failure to respond" and biological arrays confirmed these findings.

Predictive factors of the response of rectal cancer to neoadjuvant radiochemotherapy

Locally advanced rectal cancer is currently treated with pre-operative radiochemotherapy (pRCT), but the response is not uniform. Identification of patients with higher likelihood of responding to pRCT is clinically relevant, as patients with resistant tumors could be spared exposure to radiation or DNA-damaging drugs that are associated with adverse side effects. To highlight predictive biomarkers of response to pRCT, a systematic search of PubMed was conducted with a combination of the following terms: "rectal", "predictive", "radiochemotherapy", "neoadjuvant", "response" and "biomarkers". Genetic polymorphisms in epithelial growth factor receptor (EGFR) and thymidylate synthase (TS) genes, the expression of several markers, such as EGFR, bcl-2/bax and cyclooxygenase (COX)-2, and circulating biomarkers, such as serum carcinoembryonic antigen (CEA) level, are promising as predictor markers, but need to be further evaluated. The majority of the studies did not support the predictive value of p53, while the values of Ki-67, TS and p21 is still controversial. Gene expression profiles of thousands of genes using microarrays, microRNA studies and the search for new circulating molecules, such as human telomerase reverse transcriptase mRNA and cell-free DNA, are providing interesting results that might lead to the identification of new useful biomarkers. Evaluation of biomarkers in larger, prospective trials are required to guide therapeutic strategies.

A combined strategy of SAGE and quantitative PCR Provides a 13-gene signature that predicts preoperative chemoradiotherapy response and outcome in rectal cancer

PURPOSE

Preoperative chemoradiotherapy (CRT) is the treatment of choice for rectal cancer (RC), but half of the patients do not respond, suffer unnecessary toxicities, and surgery delays. We aimed to develop a model that could predict a clinically meaningful response to CRT by using formalin-fixed paraffin-embedded (FFPE) biopsies.

EXPERIMENTAL DESIGN

We first carried out an exploratory screening of candidate genes by using SAGE technology to evaluate dynamic changes in the RC transcriptome in selected refractory patients before and after CRT. Next, 53 genes (24 from SAGE and 29 from the literature) were analyzed by qPCR arrays in FFPE initial biopsies from 94 stage II/III RC patients who were preoperatively treated with CRT. Tumor response was defined by using Dworak's tumor regression grade (2-3-4 vs. 0-1). Multivariate Cox methods and stepwise algorithms were applied to generate an optimized predictor of response and outcome.

RESULTS

In the training cohort (57 patients), a 13-gene signature predicted tumor response with 86% accuracy, 87% sensitivity, and 82% specificity. In a testing cohort (37 patients), the model correctly classified 6 of 7 nonresponders, with an overall accuracy of 76%. A signature-based score identified patients with a higher risk of relapse in univariate (3-year disease-free survival 64% vs. 90%, P = 0.001) and multivariate analysis (HR = 4.35 95% CI: 1.2-15.75, P = 0.02), in which it remained the only statistically significant prognostic factor.

CONCLUSIONS

A basal 13-gene signature efficiently predicted CRT response and outcome. Multicentric validation by the GEMCAD collaborative group is currently ongoing. If confirmed, the predictor could be used to improve patient selection in RC studies.

Rectum-conserving surgery in the era of chemoradiotherapy

BACKGROUND

A complete pathological response occurs in 10-30 per cent of patients with locally advanced rectal cancer undergoing neoadjuvant chemoradiotherapy (CRT). The standard of care has been radical surgery with high morbidity risks and the challenges of stomata despite the favourable prognosis. This review assessed minimalist approaches (transanal excision or observation alone) to tumours with a response to CRT.

METHODS

A systematic review was performed using PubMed and Embase databases. Keywords included: 'rectal', 'cancer', 'transanal', 'conservative', 'complete pathological response', 'radiotherapy' and 'neoadjuvant'. Original articles from all relevant listings were sourced. These were hand searched for further articles of relevance. Main outcome measures assessed were rates of local recurrence and overall survival, and equivalence to radical surgery.

RESULTS

Purely conservative 'watch and wait' strategies after CRT are still controversial. Originally used for elderly patients or those who refused surgery, the data support transanal excision of rectal tumours showing a good response to CRT. A complete pathological response in the T stage (ypT0) indicates < 5 per cent risk of nodal metastases.

CONCLUSION

Rectal tumours showing an excellent response to CRT may be suitable for local excision, with equivalent outcomes to radical surgery. This approach should be the subject of prospective clinical trials in specialist centres.

Polo-like kinase 1 as predictive marker and therapeutic target for radiotherapy in rectal cancer

The ability to predict tumor sensitivity toward radiotherapy may significantly impact the selection of patients for preoperative combined-modality therapy. The aim of the present study was to test the predictive value of Polo-like kinase 1 (PLK1) in rectal cancer patients and to investigate whether PLK1 plays a direct role in mediating radiation sensitivity. PLK1 expression was evaluated by immunohistochemistry (n = 76) or Affymetrix HG133 microarray (n = 20) on pretreatment biopsies of patients with advanced rectal cancer. Expression was correlated with both tumor regression in the resected specimen and long-term clinical outcome. Furthermore, we used small interfering RNAs (siRNAs) to down-regulate PLK1 expression in colorectal cancer cells and analyzed the effects of PLK1-specific siRNAs by Western blot and quantitative real-time PCR analysis, FACScan analysis, caspase 3/7 assays, and colony-forming assays. We observed that increased PLK1 protein expression was significantly related to a poorer tumor regression and a higher risk of local recurrence in uni- and multivariate analysis. A significant decrease of PLK1 expression by siRNAs in combination with ionizing radiation induced an increased percentage of apoptotic cells and increased caspase 3/7 activity. Furthermore, enhanced G(2)-M levels, decreased cellular viability, and reduced clonogenic survival were demonstrated, indicating a radiosensitizing effect of PLK1 depletion. Therefore, PLK1 may be a novel predictive marker for radiation response as well as a promising therapeutic target in rectal cancer patients.

A large-scale candidate gene approach identifies SNPs in SOD2 and IL13 as predictive markers of response to preoperative chemoradiation in rectal cancer

Neoadjuvant radiochemotherapy followed by total mesorectal excision is now the standard treatment for locally advanced rectal cancer. However, tumor response to chemoradiation varies widely among individuals and cannot be determined before the final pathologic evaluation. The aim of this study was to identify germline genetic markers that could predict sensitivity or resistance to preoperative radiochemotherapy (RT-CT) in rectal cancer. We evaluated the predictive value of 128 single-nucleotide polymorphisms (SNPs) in 71 patients preoperatively treated by RT-CT. The selected SNPs were distributed over 76 genes that are involved in various cellular processes such as DNA repair, apoptosis, proliferation or immune response. The SNPs superoxide dismutase 2 (SOD2) rs4880 (P=0.005) and interleukin-13 (IL13) rs1800925 (P=0.0008) were significantly associated with tumor response to chemoradiation. These results reinforce the idea of using germline polymorphisms for personalized treatment.

Cytokeratin staining for complete remission in rectal cancer after chemoradiation

BACKGROUND AND AIMS

Pathologic complete remission (CR) of rectal cancer after neoadjuvant chemoradiation therapy (CRT) is generally confirmed by routine hematoxylin and eosin (H&E) staining. The aim of this study was to identify residual rectal cancer cells in primary lesions of patients with pathologic CR by immunohistochemical staining for cytokeratin.

PATIENTS AND METHODS

The medical records of 358 rectal cancer patients who underwent neoadjuvant CRT prior to radical surgery between October 2002 and August 2007 were reviewed. The authors stained sections of resected specimens of 58 patients (15.9%; 42 males; mean age 54 years) who achieved pathologic CR (as determined originally by H&E staining) with H&E and performed immunohistochemistry (IHC) using monoclonal anti-cytokeratin antibody. These stained sections were reviewed for residual rectal cancer cells by a pathologist.

RESULTS

Of the 58 patients that achieved CR by initial pathologic examinations, eight (13.8%) were found to contain tumor by cytokeratin IHC. H&E staining revealed that six of these were positive for cancer cells, but the remaining two were negative for residual rectal cancer cells.

CONCLUSION

Through better identification of residual rectal cancer cells, cytokeratin IHC offers a means of improving staging accuracy and thus provides useful information for prognosis and treatment decisions for patients with rectal cancer who had a clinical CR after CRT.

[Clinical and histopathological results after the neo-adjuvant treatment of advanced rectal tumors]

The role of the surgical intervention is decisive in treating colorectal tumors. The neo-adjuvant radio-chemotherapy has improved the efficacy of the treatment of advanced rectum tumors. In order to decrease the size and stage of advanced rectal carcinoma and to increase the rate of resecability, we introduced neoadjuvant radio-chemotherapy. We carried out neo-adjuvant and surgical treatment in case of 67 patients with rectal adenocarcinoma (T 2-4 N 1-2 M 0 ) between June 1, 2005 and July 31, 2008. The average age of the patients was 61.2 years, the division according to sex was 44 males/23 females. Regarding the local stage of the rectal process or the proximity to the sphincter, we applied radio-chemotherapy (radiotherapy 25 times altogether 45 Gy and on the first and last week for 5-5 days they received 350 mg/m 2 /day 5-FU and 20 mg/m 2 /day leucovorin chemotherapy, recently complemented with 3 x 1.8 Gy advanced boost radiation aiming at the macroscopic tumor site with security zone). Patients underwent surgery 8 weeks on average after restaging examinations. Thirty-eight patients underwent anterior rectal resection with double stapler procedure; there were 18 abdominoperineal rectal extirpations, 7 Hartmann operations and 4 per annum excisions. Compared to the preoperative staging, the histological evaluation of the resected specimens showed total remission (pT 0 N 0 ) in 11% and partial remission in 43%. The morbidity necessitating reoperation was 5.9%, without mortality and suture insufficiency. The long-term neo-adjuvant oncological treatment led to down-staging of rectal tumors in most cases and increased the resecability and rate of resection operations.

Pharmacogenetic analysis in neoadjuvant chemoradiation for rectal cancer: high incidence of somatic mutations and their relation with response

Aims: The identification of predictive markers of response to chemoradiotherapy treatment remains a promising approach for patient management in order to obtain the best response with minor side effects. Initially, we investigated whether the analysis of several markers previously studied and others not yet evaluated could predict response to 5-fluorouracil- and capecitabine-based neoadjuvant treatment in locally advanced rectal cancer. Methods & materials: We studied germline and tumoral samples of 65 stage II/III rectal patients. A panel of pharmacogenetic markers was genotyped in paired peripheral blood samples and rectal cancer tumors. Results: Our results seem to confirm the previously described association of thymidylate synthase and the prediction of chemoradiotherapy response in rectal cancer. However, it failed to confirm the clinical utility proposed for XRCC1, ERCC1, ERCC2, MTHFR and EGFR polymorphisms in blood/germline samples. Subsequently, with the aim of improving prediction of individual response and assessing the role of studied polymorphisms in response to treatment, we determined if changes in tumor response to these markers could predict clinical outcome. We found a high degree of changes between germline and tumor samples, mainly somatic mutations without microsatellite instability, and a minor frequency of loss-of-heterozygosity events. In tumoral samples, XRCC1 appeared to be significantly associated (p = 0.006) with downstaging of the tumor (odds ratio: 7.93; 95% CI: 1.03–60.83), but the increasing of TYMS low-expression alleles contradict the previous results observed in germline samples. Conclusion: The detection of somatic mutations in rectal cancer tumors led us to re-evaluate the utility of the tests performed in blood samples for these polymorphisms in rectal cancer. Furthermore, studies aimed at assessing the influence of pharmacogenetic markers in treatment response performed in blood samples should take into account the particular pattern of hypermutability present in each tumor type. We hypothesize that different patterns of hypermutability present in each tumor type would be related to the different results in association studies related to response to the treatment.

Factors influencing local failure in rectal cancer: analysis of 2315 patients from a population-based series

PURPOSE

This study aimed to identify risk factors for local failure in an effort to optimize treatment for rectal cancer.

METHODS

A total of 154 patients with local failure after abdominal resection were identified from a population-based consecutive series of 2315 patients who underwent operations for rectal cancer in the Stockholm region between January 1995 and December 2004. Surgeons trained in total mesorectal excision performed the surgery, and preoperative radiotherapy was given according to defined protocols. Data from the 9 hospitals in the region, prospectively registered in a database, were reviewed with regard to tumor location and stage, radiation therapy, surgical treatment, and follow-up.

RESULTS

In a multivariable analysis, independent risk factors for local failure were distal tumor location and advanced tumor and nodal stage, omission of preoperative radiation, residual disease, and hospitals with lower caseload. Low anterior resection and total mesorectal excision were deployed more often in centers with low failure rates. Discriminators for radiation therapy were patients with male gender, less advanced age, and tumors situated <6 cm from the anal verge.

CONCLUSION

The variability of patient outcome according to local failure depends on tumor stage, nodal stage, and location. Omission of radiation therapy and surgical performance are important additional risk factors to consider when optimizing treatment for rectal cancer.

Increased spontaneous apoptosis, but not survivin expression, is associated with histomorphologic response to neoadjuvant chemoradiation in rectal cancer

PURPOSE

Survivin has been shown to be an important mediator of cellular radioresistance in vitro. This study aims to compare survivin expression and apoptosis to histomorphologic responses to neoadjuvant radiochemotherapy (RCT) in rectal cancer.

MATERIALS AND METHODS

Thirty-six pre-treatment biopsies were studied. Survivin mRNA and protein expression plus TUNEL staining for apoptosis was performed. Response to treatment was assessed using a 5-point tumour regression grade.

RESULTS

Survivin expression was not found to be predictive of response to RCT (p = NS). In contrast, spontaneous apoptosis was significantly (p = 0.0051) associated with subsequent response to RCT. However, no association between survivin expression and levels of apoptosis could be identified.

CONCLUSIONS

This in vivo study failed to support in vitro studies showing an association between survivin and response to chemotherapy and radiation therapy. These results caution against the translation of the in vitro properties of survivin into a clinical setting.

Prognostic value of carcinoembryonic antigen level in rectal cancer treated with neoadjuvant chemoradiotherapy

BACKGROUND

The purpose of this study was to identify clinical and pathological parameters to improve prediction of disease-free survival (DFS) and overall survival (OS) in patients treated with neoadjuvant chemoradiotherapy for rectal cancer.

METHODS

Between July 1995 and May 2007, 148 patients with primary rectal adenocarcinoma received neoadjuvant chemoradiotherapy followed by mesorectal excision. Preoperative treatment included various protocols, UFT and leucovorin (28%) and oxaliplatin-based chemotherapy (72%). Clinical and pathological variables were evaluated in relation to patient outcomes.

RESULTS

Thirteen percent of patients achieved a complete pathologic response. No response or minimal response as defined by Dworak (Tumor Regression Grade 0/1) was observed in 30 patients (20%). At a median follow-up of 37 months, the 3-year DFS and OS were 64% and 83%, respectively. Pre-treatment serum carcinoembryonic antigen (CEA) level </= 2.5 ng/ml was associated with higher DFS (74 vs. 53%; p = 0.018), higher complete pathologic responses (21 vs. 9%; p = 0.05), and less recurrences (24 vs. 44%; p = 0.014).

CONCLUSION

The data suggest that a CEA level </= 2.5 ng/ml might be a predictor not only of tumor response, as has been suggested before, but also of DFS. This finding could be useful in the future to predict individual risk and to develop more aggressive or alternative strategies.

Molecular genetic changes associated with colorectal carcinogenesis are not prognostic for tumor regression following preoperative chemoradiation of rectal carcinoma

PURPOSE

Preoperative chemotherapy and radiation has become the standard of care for many patients with rectal cancer. The therapy may have toxicity and delays definitive surgery. It would therefore be desirable to identify those cancers that will not regress with preoperative therapy. We assessed a series of rectal cancers for the molecular changes of loss of heterozygosity of the APC and DCC genes, K-ras mutations, and microsatellite instability, changes that have clearly been associated with rectal carcinogenesis.

METHODS AND MATERIALS

Diagnostic colonoscopic biopsies from 53 patients who received preoperative chemotherapy and radiation were assayed using polymerase chain reaction techniques followed by single-stranded conformation polymorphism and DNA sequencing. Regression of the primary tumor was evaluated using the surgically removed specimen.

RESULTS

Twenty-three lesions (45%) were found to have a high degree of regression. None of the molecular changes were useful as indicators of regression.

CONCLUSIONS

Recognized molecular changes critical for rectal carcinogenesis including APC and DCC loss of heterozygosity, K-ras mutations, and microsatellite instability are not useful as indicators of tumor regression following chemoradiation for rectal carcinoma.

Preoperative chemoradiotherapy in locally advanced rectal cancer: correlation of a gene expression-based response signature with recurrence

Preoperative chemoradiotherapy is recommended for locally advanced rectal cancer (UICC stage II/III). We recently demonstrated that responsive and nonresponsive tumors showed differential expression levels of 54 genes. In this follow-up study, we investigated the relationship between this gene set and disease-free (DFS) and overall survival (OS). Pretherapeutic biopsies from 30 participants in the CAO/ARO/AIO-94 trial of the German Rectal Cancer Study Group were analyzed using gene expression microarrays. Statistical analysis was performed to identify differentially expressed genes between recurrent and nonrecurrent tumors and to correlate these changes with disease recurrence and outcome. After a median follow-up of 59 months, seven of eight patients with recurrent disease was a nonresponder, and one responsive tumor recurred. Response to chemoradiotherapy was significantly correlated with an improved DFS (log rank P=0.028), whereas OS did not differ significantly (P=0.11). Applying a class comparison analysis, we identified 20 genes that were differentially expressed between recurrent and nonrecurrent tumors (P<0.001). Analyzing the first two principal components of the 54 genes previously identified to predict response, we observed that this response signature correlated with an increased risk of cancer recurrence. These data suggest that the genetic basis of local response also affects the genetic basis of tumor recurrence. Genes that are indicative of nonresponse to preoperative chemoradiotherapy might also be linked to an increased risk of tumor recurrence.

Caveolin-1 as a prognostic marker for local control after preoperative chemoradiation therapy in rectal cancer

PURPOSE

Caveolin-1 is a protein marker for caveolae organelles and has an essential impact on cellular signal transduction pathways (e.g., receptor tyrosine kinases, adhesion molecules, and G-protein-coupled receptors). In the present study, we investigated the expression of caveolin-1 in patients with rectal adenocarcinoma and correlated its expression pattern with the risk for disease recurrences after preoperative chemoradiation therapy (CRT) and surgical resection.

METHODS AND MATERIALS

Caveolin-1 mRNA and protein expression were evaluated by Affymetrix microarray analysis (n = 20) and immunohistochemistry (n = 44) on pretreatment biopsy samples of patients with locally advanced adenocarcinoma of the rectum, and were correlated with clinical and histopathologic characteristics as well as with 5-year rates of local failure and overall survival.

RESULTS

A significantly decreased median caveolin-1 intracellular mRNA level was observed in tumor biopsy samples as compared with noncancerous mucosa. Individual mRNA levels and immunohistologic staining, however, revealed an overexpression in 7 of 20 patients (35%) and 17 of 44 patients (38.6%), respectively. Based on immunohistochemical evaluation, local control rates at 5 years for patients with tumors showing low caveolin-1 expression were significantly better than for patients with high caveolin-1-expressing carcinoma cells (p = 0.05; 92%, 95% confidence interval [95% CI] = 82-102% vs. 72%, 95% CI = 49-84%). A low caveolin-1 protein expression was also significantly related to an increased overall survival rate (p = 0.05; 45%, 95% CI 16-60% vs. 82%, 95% CI = 67-97%).

CONCLUSION

Caveolin-1 may provide a novel prognostic marker for local control and survival after preoperative CRT and surgical resection in rectal cancer.

Biologically conformal treatment: biomarkers and functional imaging in radiation oncology

'Conformal radiation therapy' is the standard of care in radiation oncology, referring to the process of shaping the radiation beam to precisely match a tumor's physical dimensions. We describe 'biologically conformal radiotherapy', in which the radiation oncologist matches the prescribed treatment to a tumor's biological characteristics and the host's predicted tolerance of radiation. This paradigm emphasizes that not all tumors are equally sensitive to radiation; conversely, some patients are especially susceptible to radiation's side effects. Patients bearing radioresistant tumors or those prone to toxicity may be best treated with the incorporation of targeted radiation modulators or, in extreme cases, by a different modality. The biological characteristics of tumors can be assessed by a wide range of techniques: functional imaging (positron emission tomography and advanced magnetic resonance imaging), single gene/protein molecular techniques and 'omic' technologies. This paper reviews the latest advances in the use of biomarkers and functional imaging in guiding patients to receive the most appropriate treatment.

Carcinoembryonic antigen as a predictor of pathologic response and a prognostic factor in locally advanced rectal cancer patients treated with preoperative chemoradiotherapy and surgery

PURPOSE

To evaluate the role of serum carcinoembryonic antigen (CEA) as a predictor of response to preoperative chemoradiotherapy (CRT) and prognostic factor for rectal cancer.

MATERIALS AND METHODS

The study retrospectively evaluated 352 locally advanced rectal cancer patients who underwent preoperative CRT followed by surgery. Serum CEA levels were determined before CRT administration (pre-CRT CEA) and before surgery (post-CRT CEA). Correlations between pre-CRT CEA levels and rates of good response (Tumor regression grade 3/4) were explored. Patients were categorized into three CEA groups according to their pre-/post-CRT CEA levels (ng/mL) (Group A: pre-CRT CEA <or= 3; B: pre-CRT CEA >3, post-CRT CEA <or=3; C: pre- and post-CRT CEA >3 ng/mL), and their oncologic outcomes were compared.

RESULTS

Of 352 patients, good responses were achieved in 94 patients (26.7%). The rates of good response decreased significantly as the pre-CRT CEA levels became more elevated (CEA [ng/mL]: <or=3, 36.4%; 3-6, 23.6%; 6-9, 15.6%; >9, 7.8%; p < 0.001). The rates of good response were significantly higher in Group A than in Groups B and C (36.4% vs. 17.3% and 14.3%, respectively; p < 0.001). The 3-year disease-free survival rate was significantly better in Groups A and B than in Group C (82% and 79% vs. 57%, respectively; p = 0.005); the CEA grouping was identified as an independent prognostic factor (p = 0.025).

CONCLUSIONS

In locally advanced rectal cancer patients, CEA levels could be of clinical value as a predictor of response to preoperative CRT and as an independent prognostic factor after preoperative CRT and curative surgery.

Preoperative radiochemotherapy is successful also in patients with locally advanced rectal cancer who have intrinsically high apoptotic tumours

BACKGROUND

Not all patients with locally advanced rectal cancer (LARC) respond equally to neo-adjuvant radiochemotherapy (RCT). Patients with highly apoptotic less advanced rectal cancers do not benefit from short-term radiotherapy. This study investigates whether this is also the case in the setting of RCT for LARC.

PATIENTS AND METHODS

Tissue microarrays were constructed of biopsy and resection specimens of 201 LARC patients. Apoptosis (M30) and several apoptosis-regulating proteins [p53, Bcl-2, Bax, cyclooxygenase-2 (Cox-2) and mamma serine protease inhibitor (maspin)] were studied with immunohistochemistry. Subsequently, predictive values for local recurrence (LR), overall survival (OS) and histological tumour regression were analysed.

RESULTS

Apoptotic levels, quantified as the number of apoptotic cells/mm(2) tumour epithelium, were higher in posttherapy tissues compared with biopsies (P < 0.001). Biopsies from clinical T4 stage tumours demonstrated significantly higher levels of apoptosis than clinical T3 stage tumours (P = 0.020). Therapy-induced apoptosis was higher when the interval between the last day of irradiation and surgery increased (P < 0.001, correlation coefficient = 0.355). Pre- and posttherapy apoptosis, p53, Bcl-2, Bax and Cox-2 were not associated with LR, OS or tumour regression. Intense pretherapy cytoplasmatic staining of maspin indicated a higher risk on LR (P = 0.009) only.

CONCLUSION

Combined RCT is also successful in highly apoptotic tumours and is therefore independent of intrinsic apoptosis.

Circulating lymphangiogenic growth factors in gastrointestinal solid tumors, could they be of any clinical significance?

Metastasis is the principal cause of cancer mortality, with the lymphatic system being the first route of tumor dissemination. The glycoproteins VEGF-C and VEGF-D are members of the vascular endothelial growth factor (VEGF) family, whose role has been recently recognized as lymphatic system regulators during embryogenesis and in pathological processes such as inflammation, lymphatic system disorders and malignant tumor metastasis. They are ligands for the VEGFR-3 receptor on the membrane of the lymphatic endothelial cell, resulting in dilatation of existing lymphatic vessels as well as in vegetation of new ones (lymphangiogenesis). Their determination is feasible in the circulating blood by immunoabsorption and in the tissue specimen by immunohistochemistry and reverse transcription polymerase chain reaction (RT-PCR). Experimental and clinicopathological studies have linked the VEGF-C, VEGF-D/VEGFR3 axis to lymphatic spread as well as to the clinical outcome in several human solid tumors. The majority of these data are derived from surgical specimens and malignant cell series, rendering their clinical application questionable, due to subjectivity factors and post-treatment quantification. In an effort to overcome these drawbacks, an alternative method of immunodetection of the circulating levels of these molecules has been used in studies on gastric, esophageal and colorectal cancer. Their results denote that quantification of VEGF-C and VEGF-D in blood samples could serve as lymph node metastasis predictive biomarkers and contribute to preoperative staging of gastrointestinal malignancies.

Predictive value of Ki67 and p53 in locally advanced rectal cancer: Correlation with thymidylate synthase and histopathological tumor regression after neoadjuvant 5-FU-based chemoradiotherapy

AIM: To investigate the predictive value of Ki67 and p53 and their correlation with thymidylate synthase (TS) gene expression in a rectal cancer patient cohort treated according to a standardized recommended neoadjuvant treatment regimen.

METHODS: Formalin fixed, paraffin embedded pre-therapeutical tumor biopsies (n = 22) and post-therapeutical resection specimens (n = 40) from patients with rectal adenocarcinoma (clinical UICC stage II/III) receiving standardized neoadjuvant 5-fluorouracil (5-FU) based chemoradiotherapy were studied for Ki67 and p53 expression by immunohistochemistry and correlated with TS mRNA expression by quantitative TaqMan real-time PCR after laser microdissection. The results were compared with histopathological tumor regression according to a standardized semiquantitative score grading system.

RESULTS: Responders (patients with high tumor regression) showed a significantly lower Ki67 expression than non-responders in the pre-therapeutical tumor biopsies (81.2% vs 16.7%; P < 0.05) as well as in the post-therapeutical resection specimens (75.8% vs 14.3%; P < 0.01). High TS mRNA expression was significantly correlated with a high Ki67 index and low TS mRNA expression was significantly correlated with a low Ki67 index in the pre-therapeutical tumor biopsies (corr. coef. = 0.46; P < 0.01) as well as in the post-therapeutical resection specimens (corr. coef. = 0.40; P < 0.05). No significant association was found between p53 and TS mRNA expression or tumor regression.

CONCLUSION: Ki67 has, like TS, predictive value in rectal cancer patients after neoadjuvant 5-FU based chemoradiotherapy. The close correlation between Ki67 and TS indicates that TS is involved in active cell cycle processes.

Rectal cancer radiotherapy

Adjuvant therapy for rectal cancer has undergone significant modifications over the past 30 years, including the addition of radiation therapy, significant improvements in surgical technique, and the administration of systemic therapy. Historically, curative resection commonly required an abdominoperineal resection and permanent colostomy. Adjuvant radiation therapy not only improved local control and overall survival, but allowed the opportunity for sphincter-preserving resections in patients with adequate sphincter function and tumors located approximately 1-2 cm from the dentate line. Local recurrence, a primary mode of failure in rectal cancer, has been improved by the development of the total mesorectal excision, with en-bloc resection of the rectum and its lymphovascular mesentery, the mesorectum. Removing micrometastatic disease within the mesorectum has also enhanced sphincter preservation without compromising local control or survival. Locoregional recurrence has remained a significant issue for patients with locally advanced disease (node positive or high T stage). Multiple studies have shown that the addition of chemotherapy further improves outcomes versus surgery alone or combined surgery and radiation, due both to the radiosensitizing properties of certain systemic agents as well as to the direct cytotoxic effect of the chemotherapy on micrometastatic disease. Adjuvant concurrent chemoirradiation in locally advanced rectal cancer confers a significant improvement in local control and overall survival compared with either modality alone. The future direction of treatment for rectal cancer will certainly consist of improved imaging and other diagnostic techniques to determine more accurately the need for adjuvant therapy. Multimodality therapy with radiotherapy administered in combination with systemic and biologic agents as radiation sensitizers is currently under investigation and may allow for improved local control and perhaps allow for minimizing the extent of surgery in selected situations.

Combined analysis of VEGF and EGFR predicts complete tumour response in rectal cancer treated with preoperative radiotherapy

The ability to predict complete pathologic response or sensitivity to radiation before treatment would have a significant impact on the selection of patients for preoperative radiotherapy or chemo-radiation therapy schedules. The aim of this study was to determine the value of epidermal growth factor receptor (EGFR), vascular endothelial growth factor (VEGF), p53, Bcl-2 and apoptosis protease-activating factor-1 (APAF-1) as predictors of complete pathologic tumour regression in patients undergoing preoperative radiotherapy for advanced rectal cancer. Pretreatment tumour biopsies from predominantly cT3 patients undergoing a preoperative high-dose-rate brachytherapy protocol were immunostained for EGFR, VEGF, p53, Bcl-2 and APAF-1. Immunoreactivity was evaluated by three pathologists. Cut-off scores for tumour marker positivity were obtained by receiver-operating characteristic (ROC) curve analysis. The association of marker expression with complete pathologic response was analysed in univariate and multivariable analysis. Multi-marker phenotypes of the independent protein markers were evaluated. In multivariable analysis, loss of VEGF (P-value=0.009; odds ratio (OR) (95% CI)=0.24 (0.08–0.69)) and positive EGFR (P-value=0.01; OR (95% CI)=3.82 (1.37–10.6)) both demonstrated independent predictive value for complete pathologic response. The odds of complete response were 12.8 for the multi-marker combination of VEGF-negative and EGFR-positive tumours. Of the 34 EGFR-negative- and VEGF-positive cases, 32 (94.1%) had no complete pathologic response. The combined analysis of VEGF and EGFR is predictive of complete pathologic response in patients undergoing preoperative radiotherapy. In addition, the findings of this study have identified a subgroup of simultaneous EGFR-negative and VEGF-positive patients who are highly resistant to radiotherapy and should perhaps be considered candidates for innovative neoadjuvant combined modalities.

Long-term efficacy of preoperative radiotherapy for locally advanced low rectal cancer

BACKGROUND AND AIMS

The purpose of this study was to assess the long-term efficacy of preoperative radiotherapy for locally advanced low rectal cancer.

MATERIALS AND METHODS

Between April 1990 and June 2005, all patients who underwent surgery for low rectal cancer with a pretreatment diagnosis of T3 or resectable T4 without distant metastasis were enrolled. The total dose of radiation was 45 Gy. Patients with a partial or complete response were defined as radiotherapy responders (RT-R) and the others as radiotherapy non-responders (RT-NR). Patients who did not receive radiotherapy were termed the non-radiotherapy group (NRT). The endpoint of this study was overall survival and local and/or distant metastasis.

RESULTS

There were 24 patients in RT-R, 26 in RT-NR, and 40 in NRT. Gastrointestinal complications were commonly observed in all groups. RT-R had a significantly higher incidence of genitourinary complications. Five-year overall survival rate was 79.6% in RT-R, 58.9% in RT-NR, and 58.8% in NRT. The difference was significant in favor of RT-R over the others (P=0.015, 0.024, respectively). Five-year local recurrence-free survival rate was 100% in RT-R, 81.5% in RT-NR, and 74.9% in NRT. RT-R had significantly improved local control compared with the others (P=0.034, 0.021, respectively). Five-year distant metastasis-free survival was not statistically different among all groups.

CONCLUSIONS

Survival benefit of preoperative radiotherapy was limited to responders. Considering the increased risk of adverse effects, identification of predictors of radiosensitivity is required in order to provide the most suitable treatment for individual patients.

Survivin, p53, and Ki-67 as predictors of histopathologic response in locally advanced rectal cancer treated with preoperative chemoradiotherapy

PURPOSE

The ability to predict response to chemoradiotherapy before the treatment may allow protecting poorly responding patients from the side effects of neoadjuvant treatment. Several molecular markers have been proposed to radio and chemosensitivity of rectal cancer. In this study, from pre-irradiation tumor biopsies, a novel and promising candidate factor survivin, and p53 and Ki-67 were assessed as predictors of response to preoperative chemoradiotherapy.

MATERIALS AND METHODS

Expression of each marker was evaluated by immunohistochemistry on pretreatment biopsies from 37 patients having rectal cancer treated with preoperative chemoradiotherapy and curative surgery. Treatment response was assessed histopathologically in the resected surgical specimen.

RESULTS

There was no correlation between expression of p53, Ki-67, and survivin with response to preoperative chemoradiotherapy and prognosis.

CONCLUSIONS

Our data suggest that these molecular markers are not helpful to identify patients who would have benefit from neoadjuvant treatment of rectal cancer. Further investigations are necessary to select patients for preoperative treatment based on analysis of the preoperative biopsies.

Microarray-based prediction of tumor response to neoadjuvant radiochemotherapy of patients with locally advanced rectal cancer

BACKGROUND & AIMS

Neoadjuvant chemoradiotherapy has become a standard treatment of locally advanced rectal carcinomas, even though the responsiveness varies from complete response to resistance. The aim of the study was to evaluate the capacity of gene expression signatures to identify responders and nonresponders pretherapeutically.

METHODS

By using microarray technology we generated gene expression profiles of 43 biopsy specimens of locally advanced rectal carcinomas. The transcription profile then was compared with histopathologic response and used to identify a set of genes discriminating responders from nonresponders.

RESULTS

We identified a gene expression signature of 42 genes, mostly encoding proteins that either play a role in the nucleus, such as the transcription factor ETS2, or are associated with transport function, such as the solute carrier SLC35E1, or the regulation of apoptosis, such as caspase-1. In leave-one-out cross-validation the correct classification of a responder was 71%, the specificity of the analysis for a correct classification of a nonresponder was 86%. By applying an additional statistical method of 200 successive splittings into training and test data sets we generated an individual prediction accuracy measure for each predicted response.

CONCLUSIONS

Our study shows that pretherapeutic prediction of response of rectal carcinomas to neoadjuvant chemoradiotherapy is feasible, and may represent a new valuable and practical tool of therapeutic stratification.

Gene expression profiling reveals two separate mechanisms regulating apoptosis in rectal carcinomas in vivo

The level of apoptosis in rectal carcinomas of patients treated by surgery only predicts local failure; patients with intrinsically high-apoptotic tumors develop less local recurrences than patients with low levels of apoptosis. To identify genes involved in this intrinsic apoptotic process in vivo, 47 rectal tumors with known apoptotic phenotype (24 low- and 23 high-apoptotic) were analyzed by oligonucleotide microarray technology. We identified several genes differentially expressed between low- and high-apoptotic tumors. Unsupervised clustering of the tumors based on expression levels of these genes separated the low-apoptotic from the high-apoptotic tumors, indicating a gene expression-dependent regulation. In addition, this clustering revealed two subgroups of high-apoptotic tumors. One high-apoptotic subgroup showed subtle differences in mRNA and protein expression of the known apoptotic regulators BAX, cIAP2 and ARC compared to the low-apoptotic tumors. The other subgroup of high-apoptotic tumors showed high expression of immune-related genes; predominantly HLA class II and chemokines, but also HLA class I and interferon-inducible genes were highly expressed. Immunohistochemistry revealed HLA-DR expression in epithelial tumor cells in 70% of these high-apoptotic tumors. The expression data suggest that high levels of apoptosis in rectal carcinoma patients can be the result of either slightly altered expression of known pro- and anti-apoptotic genes or high expression of immune-related genes.

Germline polymorphisms may act as predictors of response to preoperative chemoradiation in locally advanced T3 rectal tumors

PURPOSE

Patients with locally advanced T3 rectal tumors who present with complete pathologic response to preoperative chemoradiation have a low rate of local recurrence and an excellent prognosis. Predictive markers for complete pathologic response are needed with the perspective of improving individualized treatment of these patients. This study was designed to investigate the predictive value of a new combination of three gene polymorphisms: thymidylate synthase, epidermal growth factor receptor Sp1-216, and epidermal growth factor A61G.

METHODS

Pretreatment blood samples from 60 patients with locally advanced T3 rectal tumors were analyzed for thymidylate synthase, epidermal growth factor receptor Sp1-216, and epidermal growth factor A61G gene polymorphisms by polymerase chain reaction. Treatment consisted of preoperative radiotherapy (total dose 65 Gy) and concomitant chemotherapy (Uftoral) followed by total mesorectal excision eight weeks after treatment. Pathologic response was evaluated according to the tumor regression grade system.

RESULTS

Thirty percent (18/60) of patients presented with complete pathologic response. Patients with thymidylate synthase genotype 2/2 had a significantly higher rate of complete pathologic response with 53 percent (8/15) compared with 22 percent in the 2/3 or 3/3 group. When combining thymidylate synthase and epidermal growth factor A61G genotype analysis, a small subgroup with a complete pathologic response rate of 100 percent was identified. Only a minor proportion of the complete responders were identified by this combination. Adding the epidermal growth factor receptor Sp1-216 genotype analysis, a complete pathologic response rate of 64 percent in the combination group was found compared with 21 percent and an 87 percent risk of being a noncomplete responder in the noncombination group.

CONCLUSIONS

A promising new combination of predictive markers for complete pathologic response was presented and warrants further investigation in prospective clinical trials.

Non-operative treatment after neoadjuvant chemoradiotherapy for rectal cancer

The past decade has seen pronounced changes in the treatment of locally advanced rectal cancer. Historically, the standard of care involved surgery followed by adjuvant radiotherapy or chemoradiotherapy. More recently, the emergence of neo-adjuvant chemoradiotherapy has fundamentally changed the management of patients with locally advanced disease. In clinical trials, pathological complete responses of up to 25% have raised the question as to whether surgery can be avoided in a select cohort of patients. A trial of omission of surgery for selected patients with complete response after preoperative chemoradiotherapy has shown favourable long-term results. In this article, we outline emerging factors for achieving pathological complete response, non-operative strategies to date, methods for prediction of response to chemoradiotherapy, and future directions with the addition of MRI as a radiological guide to complete response.

Predicting the response of localised oesophageal cancer to neo-adjuvant chemoradiation

BACKGROUND

A complete pathological response to neo-adjuvant chemo-radiation for oesophageal cancer is associated with favourable survival. However, such a benefit is seen in the minority. If one could identify, at diagnosis, those patients who were unlikely to respond unnecessary toxicity could be avoided and alternative treatment can be considered. The aim of this review was to highlight predictive markers currently assessed and evaluate their clinical utility.

METHODS

A systematic search of Pubmed and Google Scholar was performed using the following keywords; "neo-adjuvant", "oesophageal", "trimodality", "chemotherapy", "radiotherapy", "chemoradiation" and "predict". The original manuscripts were sourced for further articles of relevance.

RESULTS

Conventional indices including tumour stage and grade seem unable to predict histological response. Immuno-histochemical markers have been extensively studied, but none has made its way into routine clinical practice. Global gene expression from fresh pre-treatment tissue using cDNA microarray has only recently been assessed, but shows considerable promise. Molecular imaging using FDG-PET seems to be able to predict response after neo-adjuvant chemoradiation has finished, but there is a paucity of data when such imaging is performed earlier.

CONCLUSION

Currently there are no clinically useful predictors of response based on standard pathological assessment and immunohistochemistry. Genomics, proteomics and molecular imaging may hold promise.

Combination of SELDI-TOF-MS and data mining provides early-stage response prediction for rectal tumors undergoing multimodal neoadjuvant therapy

OBJECTIVE

We investigated whether proteomic analysis of the low molecular weight region of the serum proteome could predict histologic response of locally advanced rectal cancer to neoadjuvant radiochemotherapy (RCT).

SUMMARY BACKGROUND DATA

Proteomic analysis of serum is emerging as a powerful new modality in cancer, in terms of both screening and monitoring response to treatment. No study has yet assessed its ability to predict and monitor the response of rectal cancer to RCT.

METHODS

Sequential serum samples from 20 patients undergoing RCT were prospectively collected. Time points sampled were as follows: pretreatment, 24/48 hours, 1 week, 2 weeks, 3 weeks, 5 weeks (last day of RCT), and presurgery. Response to treatment was measured using a 5-point tumor regression grade (TRG) based on the degree of residual tumor to fibrosis. All serum samples were analyzed in duplicate using surface-enhanced laser desorption/ionization-time of flight mass spectrometry (SELDI-TOF-MS). Support vector machine (SVM) analysis of spectra was used to generate a predictive algorithm for each time point based on proteins that were maximally differentially expressed between good and poor responders. This algorithm was then tested using leave-one-out cross validation.

RESULTS

In total, 230 spectra were generated representing all available time points from 9 good responders (TRG 1+2) and 11 poor responders (TRG 3-5). SVM analysis indicated that changes within the serum proteome at the 24/48 hours time point into treatment provided optimal classification accuracy. In more detail, a cohort of 14 protein peaks were identified that collectively differentiated between good and poor responders, with 87.5% sensitivity and 80% specificity.

CONCLUSIONS

Serum proteomic analysis may represent an early response predictor in multimodal treatment regimens of rectal cancer. These data suggest that this novel, minimally invasive modality may be a useful adjunct in the multimodal management of rectal cancer, and in the design of future clinical trials.

MRI after preoperative radiotherapy for rectal cancer; correlation with histopathology and the role of volumetry

The objective is to assess if tumor size after radiotherapy in patients with rectal cancer can be assessed by a second magnetic resonance imaging (MRI), after radiotherapy prior to surgery and to correlate changes observed on MRI with findings at histopathology at surgery. Twenty-five patients with MRI before and after radiotherapy were included. Variables studied were changes in tumor size, T-staging and distance to the circumferential resection margin (CRM). RVs was measured as tumor volume at surgery (Vs) divided by tumor volume at the initial MRI (Vi) in percent. RVm was defined as the tumor volume at the second MRI (Vm) divided by Vi in percent. The ypT-stage was the same or more favorable than the initial MRI T-stage in 24 of 25 patients. The second MRI was not more accurately predictive than the initial MRI for ypT-staging or distance to CRM (p > 0.05). Vm correlated significantly to Vs, as did RVs to RVm, although the former was always smaller than the latter. Vm and RVm correlated well with ypT-stage (p < 0.001). Volumetry seems to correlate with ypT-stage after preoperative radiotherapy for resectable rectal cancer. The value of a second MRI after radiotherapy for assessment of distance to CRM and ypT-staging is, however, not apparent.

Multivariate analysis approach to the plasma protein profile of patients with advanced colorectal cancer

The aim of the present study was to identify the pattern of plasma protein species of interest as markers of colorectal cancer (CRC). Using matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS), the plasma protein profile was determined in nine stage IV CRC patients (study group) and nine clean-colon healthy subjects (control group). Multivariate analysis methods were employed to identify distinctive disease patterns at protein spectrum. In the study and control groups, cluster analysis (CA) on the complete MALDI-MS spectra plasma protein profile showed a distinction between CRC patients and healthy subjects, thus allowing the identification of the most discriminating ionic species. Principal component analysis (PCA) and linear discriminant analysis (LDA) yielded similar grouping results. LDA with leave-one-out cross validation achieved a correct classification rate of 89% in both the patients and the healthy subjects.