Microsatellite Instability and Adjuvant Chemotherapy in Stage II Colon Cancer. Am J Clin Oncol. 2019;42:573-580. [PMID: 31166206 DOI: 10.1097/coc.0000000000000554]

Use of Circulating Tumor DNA to Guide Decision-making in Adjuvant Colon Cancer

PURPOSE OF REVIEW

The use of circulating tumor DNA (ctDNA) assays to guide clinical decision-making in early-stage colon cancer is an area of rapidly advancing active research. With assays clinically available, clinicians must be informed how to best use this novel tool to treat patients.

RECENT FINDINGS

Recent observational and prospective studies have suggested that ctDNA has potential to guide clinical decision-making in early-stage colon cancer by detecting minimal residual disease (MRD) and predicting recurrence risks. MRD-negative patients may be able to de-escalate or forgo adjuvant chemotherapy (ACT) without compromising disease-free survival or overall survival, while MRD-positive patients may benefit significantly from ACT. Recent and ongoing studies have given reason for optimism about the future of ctDNA as a useful biomarker for clinicians treating early-stage colon cancer. Data thus far are mostly limited to observational studies; inconsistent results highlight the need for caution. As more evidence emerges, ctDNA may become standard of care for colon cancer patients.

Analysis of clinical characteristics of mismatch repair status in colorectal cancer: a multicenter retrospective study

BACKGROUND

Microsatellite instability (MSI) caused by DNA mismatch repair (MMR) deficiency is of great significance in the occurrence, diagnosis and treatment of colorectal cancer (CRC).

AIM

This study aimed to analyze the relationship between mismatch repair status and clinical characteristics of CRC.

METHODS

The histopathological results and clinical characteristics of 2029 patients who suffered from CRC and underwent surgery at two centers from 2018 to 2020 were determined. After screening the importance of clinical characteristics through machine learning algorithms, the patients were divided into deficient mismatch repair (dMMR) and proficient mismatch repair (pMMR) groups based on the immunohistochemistry results and the clinical feature data between the two groups were observed by statistical methods.

RESULTS

The dMMR and pMMR groups had significant differences in histologic type, TNM stage, maximum tumor diameter, lymph node metastasis, differentiation grade, gross appearance, and vascular invasion. There were significant differences between the MLH1 groups in age, histologic type, TNM stage, lymph node metastasis, tumor location, and depth of invasion. The MSH2 groups were significantly different in age. The MSH6 groups had significant differences in age, histologic type, and TNM stage. There were significant differences between the PMS2 groups in lymph node metastasis and tumor location. CRC was dominated by MLH1 and PMS2 combined expression loss (41.77%). There was a positive correlation between MLH1 and MSH2 and between MSH6 and PMS2 as well.

CONCLUSIONS

The proportion of mucinous adenocarcinoma, protruding type, and poor differentiation is relatively high in dMMR CRCs, but lymph node metastasis is rare. It is worth noting that the expression of MMR protein has different prognostic significance in different stages of CRC disease.

Radiologic T staging of colon cancer: renewed interest for clinical practice

Radiologic imaging, especially MRI, has long been the mainstay for rectal cancer staging and patient selection for neoadjuvant therapy prior to surgical resection. In contrast, colonoscopy and CT have been the standard for colon cancer diagnosis and metastasis staging with T and N staging often performed at the time of surgical resection. With recent clinical trials exploring the expansion of the use of neoadjuvant therapy beyond the anorectum to the remainder of the colon, the current and future state of colon cancer treatment is evolving with a renewed interest in evaluating the role radiology may play in the primary T staging of colon cancer. The performance of CT, CT colonography, MRI, and FDG PET-CT for colon cancer staging will be reviewed. N staging will also be briefly discussed. It is expected that accurate radiologic T staging will significantly impact future clinical decisions regarding the neoadjuvant versus surgical management of colon cancer.

Exploring the Expression and Prognosis of Mismatch Repair Proteins and PD-L1 in Colorectal Cancer in a Chinese Cohort

Purpose

Exploring the expression and prognosis of mismatch repair proteins and PD-L1 in colorectal cancer.

Patients and Methods

A total of 272 patients with surgically resected CRC were enrolled in the study from January 2018 to May 2022 at Nanjing Drum Tower Hospital (The Affiliated Hospital of Nanjing University Medical School). Surgically resected samples were collected from patients along with general, clinicopathological, and imaging data for each patient. Immunohistochemistry (IHC) was used to detect expression of MSH2, MSH6, MLH1, and PMS2 proteins in tumor tissue. X-squared (X2) testing was performed to investigate the correlation between expression of MMR proteins and PD-L1 in CRC tumor tissues and clinicopathological characteristics. Correlation analysis was also used to compare the deletion of four MMR proteins in CRC tumor tissues. A survival curve and Log rank test were used to investigate the relationship between the expression of MMR proteins and PD-L1 with regard to CRC patient prognosis and survival.

Results

MMR protein expression deletion was correlated with tumor location, the degree of tissue differentiation, and TNM stage (P<0.05). PD-L1 expression was correlated with TNM stage (P<0.05). Correlation analysis of deletion of MMR protein isoform expression found that PMS2 deletion was significantly correlated with MLH1 deletion (P<0.05). Similarly, MSH2 deletion was significantly correlated with MSH6 deletion (P<0.05). PMS2 deletion was also found to be correlated with PD-L1 expression (P<0.05). Progression-free survival was found to be significantly longer in mismatch repair-proficient (pMMR) patients compared with mismatch repair-deficient (dMMR) patients.

Conclusion

Deletion of MMR proteins and expression of PD-L1 are closely related to clinicopathological characteristics and overall prognosis of CRC patients. This suggests the relevance of MMR and PD-L1 as potential biomarkers for treatment of CRC patients.

Practical recommendations for using ctDNA in clinical decision making

The continuous improvement in cancer care over the past decade has led to a gradual decrease in cancer-related deaths. This is largely attributed to improved treatment and disease management strategies. Early detection of recurrence using blood-based biomarkers such as circulating tumour DNA (ctDNA) is being increasingly used in clinical practice. Emerging real-world data shows the utility of ctDNA in detecting molecular residual disease and in treatment-response monitoring, helping clinicians to optimize treatment and surveillance strategies. Many studies have indicated ctDNA to be a sensitive and specific biomarker for recurrence. However, most of these studies are largely observational or anecdotal in nature, and peer-reviewed data regarding the use of ctDNA are mainly indication-specific. Here we provide general recommendations on the clinical utility of ctDNA and how to interpret ctDNA analysis in different treatment settings, especially in patients with solid tumours. Specifically, we provide an understanding around the implications, strengths and limitations of this novel biomarker and how to best apply the results in clinical practice.

Colorectal Cancer Liver Metastases: Genomics and Biomarkers with Focus on Local Therapies

Molecular cancer biomarkers help personalize treatment, predict oncologic outcomes, and identify patients who can benefit from specific targeted therapies. Colorectal cancer (CRC) is the third-most common cancer, with the liver being the most frequent visceral metastatic site. KRAS, NRAS, BRAF V600E Mutations, DNA Mismatch Repair Deficiency/Microsatellite Instability Status, HER2 Amplification, and NTRK Fusions are NCCN approved and actionable molecular biomarkers for colorectal cancer. Additional biomarkers are also described and can be helpful in different image-guided hepatic directed therapies specifically for CRLM. For example, tumors maintaining the Ki-67 proliferation marker after thermal ablation was shown to be particularly resilient to ablation. Ablation margin was also shown to be an important factor in predicting local recurrence, with a ≥10 mm minimal ablation margin being required to attain local tumor control, especially for patients with mutant KRAS CRLM.

Adjuvant chemotherapy and survival outcomes in rectal cancer patients with good response (ypT0-2N0) after neoadjuvant chemoradiotherapy and surgery: A retrospective nationwide analysis

Background

For rectal cancer, it remains unclear how to incorporate tumor response to neoadjuvant chemoradiotherapy (nCRT) when deciding whether to give adjuvant chemotherapy. In this study, we aim to determinate the survival benefit of adjuvant chemotherapy for rectal cancer patients with good response (ypT0-2N0) after nCRT and surgery.

Methods

The study cohort included 720 rectal cancer patients who had good response (ypT0-2N0) after nCRT and surgery, who did or did not receive adjuvant chemotherapy between January 2007 and December 2017, from the Taiwan Cancer Registry and National Health Insurance Research database. The Kaplan-Meier method, log-rank tests, and Cox regression analysis were performed to investigate the effect of adjuvant chemotherapy on 5-year overall survival (OS) and disease-free survival (DFS).

Results

Of 720 patients, 368 (51.1%) received adjuvant chemotherapy and 352 (48.9%) did not. Patients who received adjuvant chemotherapy were more likely to be female, younger (≤ 65), with advanced clinical T (3-4)/N (1-2) classification and ypT2 classification. No significant difference in 5-year OS (p=0.681) or DFS (p=0.942) were observed by receipt of adjuvant chemotherapy or not. Multivariable analysis revealed adjuvant chemotherapy was not associated with better OS (adjusted hazard ratio [aHR], 1.03; 95% Confidence Interval [CI], 0.88-1.21) or DFS (aHR, 1.05; 95% CI, 0.89-1.24). Stratified analysis for OS and DFS found no significant protective effect in the use of adjuvant chemotherapy, even for those with advanced clinical T or N classification.

Conclusion

Adjuvant chemotherapy may be omitted in rectal cancer patients with good response (ypT0-2N0) after nCRT and surgery.

Biomarkers in Metastatic Colorectal Cancer: Status Quo and Future Perspective

Colorectal cancer (CRC) is the third most frequent cancer worldwide, and its incidence is steadily increasing. During the last two decades, a tremendous improvement in outcome has been achieved, mainly due to the introduction of novel drugs, targeted treatment, immune checkpoint inhibitors (CPIs) and biomarker-driven patient selection. Moreover, progress in molecular diagnostics but also improvement in surgical techniques and local ablative treatments significantly contributed to this success. However, novel therapeutic approaches are needed to further improve outcome in patients diagnosed with metastatic CRC. Besides the established biomarkers for mCRC, such as microsatellite instability (MSI) or mismatch repair deficiency (dMMR), RAS/BRAF, sidedness and HER2 amplification, new biomarkers have to be identified to better select patients who derive the most benefit from a specific treatment. In this review, we provide an overview about therapeutic relevant and established biomarkers but also shed light on potential promising markers that may help us to better tailor therapy to the individual mCRC patient in the near future.

Approach to Resectable Gastric Cancer: Evolving Paradigm of Neoadjuvant and Adjuvant Treatment

OPINION STATEMENT

Recent therapeutic advances have prolonged survival in patients with metastatic gastric cancer, though the prognosis for patients with locally advanced resectable gastric cancer remains poor. Long-term survival after resection of locally advanced gastric adenocarcinoma is dependent on early eradication of micrometastatic disease and optimal surgical resection. Preoperative therapy with a docetaxel-containing three-drug regimen has recently been shown to be superior to an anthracycline-containing three-drug regimen or two-drug therapy with a fluoropyrimidine and platinum. Chemoradiation is not essential and is reserved for patients with suboptimal resection. Emerging research strategies include introduction of pre- and postoperative checkpoint blockade and biomarker-directed therapy.

Adjuvant Therapy for Stage II Colon Cancer: ASCO Guideline Update

PURPOSE

To develop recommendations for adjuvant therapy for patients with resected stage II colon cancer.

METHODS

ASCO convened an Expert Panel to conduct a systematic review of relevant studies and develop recommendations for clinical practice.

RESULTS

Twenty-one observational studies and six randomized controlled trials met the systematic review inclusion criteria.

RECOMMENDATIONS

Adjuvant chemotherapy (ACT) is not routinely recommended for patients with stage II colon cancer who are not in a high-risk subgroup. Patients with T4 tumors are at higher risk of recurrence and should be offered ACT, whereas patients with other high-risk factors, including sampling of fewer than 12 lymph nodes in the surgical specimen, perineural or lymphatic invasion, poorly or undifferentiated tumor grade, intestinal obstruction, tumor perforation, or grade BD3 tumor budding, may be offered ACT. The addition of oxaliplatin to fluoropyrimidine-based ACT is not routinely recommended, but may be offered as a result of shared decision making. Patients with mismatch repair deficiency/microsatellite instability tumors should not be routinely offered ACT; if the combination of mismatch repair deficiency/microsatellite instability and high-risk factors results in a decision to offer ACT, oxaliplatin-containing chemotherapy is recommended. Duration of oxaliplatin-containing chemotherapy is also addressed, with recommendations for 3 or 6 months of treatment with capecitabine and oxaliplatin or fluorouracil, leucovorin, and oxaliplatin, with decision making informed by key evidence of 5-year disease-free survival in each treatment subgroup and the rate of adverse events, including peripheral neuropathy.Additional information is available at www.asco.org/gastrointestinal-cancer-guidelines.

A Simple, Accurate and Cost-Effective Capillary Electrophoresis Test with Computational Methods to Aid in Universal Microsatellite Instability Testing

Background: Microsatellite instability (MSI) testing is important for the classification of Lynch syndrome, as a prognostic marker and as a guide for adjuvant chemotherapy in colorectal cancer (CRC). The gold standard for determining MSI status has traditionally been fluorescent multiplex polymerase chain reaction (PCR) and capillary gel electrophoresis (CGE). However, its use in the clinical setting has diminished and has been replaced by immunohistochemical (IHC) detection of loss of mismatch repair protein expression due to practicability and cost. The aim of this study was to develop a simple, cost-effective and accurate MSI assay based on CGE. Method: After amplification of microsatellites by polymerase chain reaction (PCR) using the National Cancer Institute (NCI) panel (BAT 25, BAT26, D5S346, D2S123, D17S250) of MSI markers, parallel CGE was utilized to classify colorectal cancers as MSI-H, MSI-L and MSS using the 5200 Fragment Analyzer System. Cell lines and patient cancer specimens were tested. DNA from 56 formalin-fixed paraffin-embedded cancer specimens and matched normal tissue were extracted and CGE was performed. An automated computational algorithm for MSI status determination was also developed. Results: Using the fragment analyser, MSI status was found to be 100% concordant with the known MSI status of cell lines and was 86% and 87% concordant with immunohistochemistry (IHC) from patient cancer specimens using traditional assessment and our MSI scoring system, respectively, for MSI determination. The misclassification rate was mainly attributed to IHC, with only one (1.8%) sampling error attributed to CGE testing. CGE was also able to distinguish MSI-L from MSI-H and MSS, which is not possible with IHC. An MSI score based on total allelic variability that can accurately determine MSI status was also successfully developed. A significant reduction in cost compared with traditional fluorescent multiplex PCR and CGE was achieved with this technique. Conclusions: A simple, cost-effective and reliable method of determining MSI status and an MSI scoring system based on an automatic computational algorithm to determine MSI status, as well as degree of allelic instability in colorectal cancer, has been developed using the 5200 Fragment Analyzer System.

Is Microsatellite Status Associated With Prognosis in Stage II Colon Cancer With High-Risk Features?

BACKGROUND

The influence of microsatellite instability on prognosis in high-risk stage II colon cancer is unknown.

OBJECTIVE

This study aimed to investigate the relationship between microsatellite instability and overall survival in high-risk stage II colon cancer.

DESIGN

This is a retrospective review of the National Cancer Database from 2010 to 2016.

SETTINGS

This study included national cancer epidemiology data from the American College of Surgeons Commission on Cancer.

PATIENTS

Included were 16,788 patients with stage II colon adenocarcinoma and known microsatellite status (1709 microsatellite unstable).

MAIN OUTCOME MEASURES

The primary outcome measured was overall survival.

RESULTS

Microsatellite unstable cancers with high-risk features had significantly better overall survival than microsatellite stable cancers with high-risk features (5-year survival 80% vs 72%, p = 0.01), and had survival equivalent to microsatellite stable cancers with low-risk features (5-year survival, 80%). When stratified by specific high-risk features, patients with lymphovascular invasion, perineural invasion, or high-grade histology had overall survival similar to patients without these features, only in microsatellite unstable cancers. However, patients with high-risk features of T4 stage, positive margins, and <12 lymph nodes saw no survival benefit based on microsatellite status. This was confirmed on multivariable Cox regression modeling. A subgroup analysis of patients who did not receive chemotherapy similarly demonstrated that microsatellite unstable cancers with lymphovascular invasion, perineural invasion, or high-grade histology had overall survival similar to microsatellite unstable cancers without those features.

LIMITATIONS

The study is limited by the lack of specific clinical data and potential treatment bias.

CONCLUSIONS

In microsatellite unstable cancers, lymphovascular invasion, perineural invasion, and high-grade histology are not associated with worse overall survival, even when deferring adjuvant chemotherapy. These data support National Comprehensive Cancer Network recommendations to forego chemotherapy in stage II cancers with microsatellite instability and these features. In contrast, some high-risk features were associated with worse survival despite microsatellite unstable biology, and therapies to improve survival need to be explored. See Video Abstract at http://links.lww.com/DCR/B500. ¿EL ESTADO MICROSATÉLITE ESTÁ ASOCIADO CON EL PRONÓSTICO EN EL CÁNCER DE COLON EN ESTADIO II CON CARACTERÍSTICAS DE ALTO RIESGO: Se desconoce la influencia de la inestabilidad microsatélite en el pronóstico del cáncer de colon en estadio II de alto riesgo.Investigar la relación entre la inestabilidad microsatélite y la supervivencia general en el cáncer de colon en estadio II de alto riesgo.Revisión retrospectiva de la base de datos nacional del cáncer de 2010 a 2016.Este estudio incluyó datos nacionales de epidemiología del cáncer de la Comisión de Cáncer del Colegio Americano de Cirujanos.16,788 pacientes con adenocarcinoma de colon en estadio II y estado microsatélite conocido (1,709 microsatélite inestables).Supervivencia global.Los cánceres microsatélite inestables con características de alto riesgo tuvieron una supervivencia general significativamente mejor que los cánceres microsatélite estables con características de alto riesgo (supervivencia a 5 años 80% vs 72%, p = 0.01), y tuvieron una supervivencia equivalente a los cánceres microsatélite estables con características de bajo riesgo (supervivencia a 5 años 80%). Al estratificar por características específicas de alto riesgo, los pacientes con invasión linfovascular, invasión perineural o histología de alto grado tuvieron una supervivencia general similar a la de los pacientes sin estas características, solo en cánceres microsatélite inestables. Sin embargo, los pacientes con características de alto riesgo en estadio T4, márgenes positivos y <12 ganglios linfáticos no tuvieron ningún beneficio de supervivencia basado en el estado de microsatélites. Esto se confirmó en un modelo de regresión de Cox multivariable. Un análisis de subgrupos de pacientes que no recibieron quimioterapia demostró de manera similar que los cánceres microsatélite inestables con invasión linfovascular, invasión perineural o histología de alto grado tenían una supervivencia general similar a los cánceres microsatélite inestables sin esas características.El estudio está limitado por la falta de datos clínicos específicos y el posible sesgo de tratamiento.En los cánceres microsatélite inestables, la invasión linfovascular, la invasión perineural y la histología de alto grado no se asocian con una peor sobrevida general, incluso cuando se aplaza la quimioterapia adyuvante. Estos datos respaldan las recomendaciones de la National Comprehensive Cancer Network de omitir la quimioterapia en los cánceres en estadio II con inestabilidad microsatélite y estas características. Por el contrario, algunas características de alto riesgo se asociaron con una peor supervivencia a pesar de la biología microsatélite inestable, y es necesario considerar las terapias para mejorar la supervivencia.Consulte Video Resumen en http://links.lww.com/DCR/B500. (Traducción-Dr. Jorge Silva Velazco).

Management of colorectal cancer in the era of COVID-19: Challenges and suggestions

The Coronavirus (COVID-19) pandemic had a huge impact on all sectors around the world. In particular, the healthcare system has been subject to an enormous pressure that has surpassed its ability in many instances. Additionally, the pandemic has called for a review of our daily medical practices, including our approach to colorectal cancer management where treatment puts patients at high risk of virus exposure. Given their higher median age, patients are at an increased risk for severe symptoms and complications in cases of infection, especially in the setting of immunosuppression. Therefore, a review of the routine colorectal cancer practices is needed to minimize risk of exposure. Oncologists should weigh risk of exposure versus the patient's oncologic benefits when approaching management. In addition, treatment protocols should be modified to minimize hospital visits and admissions while maintaining the same treatment efficacy. In this review, we will focus on challenges that colorectal cancer patients face during the pandemic, while highlighting the priority in each case. We will also discuss the evidence for potential modifications to existing treatment plans that could reduce infectious exposure without compromising care. Finally, we will discuss the impact of the socio-economic difficulties faced by Lebanese patients due to a poor economy toppled by an unexpected pandemic.

Detection of Microsatellite Instability: State of the Art and Future Applications in Circulating Tumour DNA (ctDNA)

Simple Summary

Microsatellite instability (MSI) is a molecular fingerprint for defects in the mismatch repair system (dMMR) and is associated with higher risks of cancers. MSI/dMMR tumours are characterized by the accumulation of mutations throughout the genome, and particularly in microsatellite (MS) DNA repeat sequences. MSI stands as a major biomarker for familial cancer risk assessment, cancer prognosis, and therapeutic choices. Standard-of-care classification of MSI/dMMR tumours is most frequently achieved using immunohistochemistry or PCR-based assay directed against a set of five MS regions. However, novel molecular methods based on tumour tissue or plasma samples have been developed and could enter in the future trends of MSI testing. Here, we provide insights into these emerging approaches and discuss their advantages and limitations.

Abstract

Microsatellite instability (MSI) is a molecular scar resulting from a defective mismatch repair system (dMMR) and associated with various malignancies. MSI tumours are characterized by the accumulation of mutations throughout the genome and particularly clustered in highly repetitive microsatellite (MS) regions. MSI/dMMR status is routinely assessed in solid tumours for the initial screening of Lynch syndrome, the evaluation of cancer prognosis, and treatment decision-making. Currently, pentaplex PCR-based methods and MMR immunohistochemistry on tumour tissue samples are the standard diagnostic methods for MSI/dMMR. Other tissue methods such as next-generation sequencing or real-time PCR-based systems have emerged and represent viable alternatives to standard MSI testing in specific settings. The evolution of the standard molecular techniques has offered the opportunity to extend MSI determination to liquid biopsy based on the analysis of cell-free DNA (cfDNA) in plasma. This review aims at synthetizing the standard and emerging techniques used on tumour tissue samples for MSI/dMMR determination. We also provide insights into the MSI molecular techniques compatible with liquid biopsy and the potential clinical consequences for patients with solid cancers.

Mismatch repair phenotype determines the implications of tumor grade and CDX2 expression in stage II-III colon cancer

Mismatch repair (MMR) deficiency is an indicator of good prognosis in localized colon cancer but also associated with lack of expression of caudal-type homeobox transcription factor 2 (CDX2) and high tumor grade; markers that in isolation indicate a poor prognosis. Our study aims to identify clinically relevant prognostic subgroups by combining information about tumor grade, MMR phenotype, and CDX2 expression. Immunohistochemistry for MMR proteins and CDX2 was performed in 544 patients with colon cancer stage II-III, including a cohort from a randomized trial. In patients with proficient MMR (pMMR) and CDX2 negativity, hazard ratio (HR) for cancer death was 2.93 (95% CI 1.23-6.99, p = 0.015). Cancer-specific survival for pMMR/CDX2-negative cases was 35.8 months (95% CI 23.4-48.3) versus 52.1-53.5 months (95% CI 45.6-58.6, p = 0.001) for the remaining cases (CDX2-positive tumors or deficient MMR (dMMR)/CDX2-negative tumors). In our randomized cohort, high tumor grade was predictive of response to adjuvant fluorouracil-levamisole in pMMR patients, with a significant interaction between tumor grade and treatment (p = 0.036). For pMMR patients, high tumor grade was a significant marker of poor prognosis in the surgery-only group (HR 4.60 (95% CI 1.68-12.61), p = 0.003) but not in the group receiving chemotherapy (HR 0.66 (95% CI 0.15-3.00), p = 0.587). To conclude, patients with pMMR and CDX2 negativity have a very poor prognosis. Patients with pMMR and high-graded tumors have a poor prognosis but respond well to adjuvant chemotherapy. CDX2 expression and tumor grade did not impact prognosis in patients with dMMR.

Correlation of tumor microenvironment from biopsy and resection specimens in untreated colorectal cancer patients: a surprising lack of agreement

Background

Colorectal cancer (CRC) tumor microenvironment (TME) characteristics, such as tumor infiltrating lymphocyte (TIL) densities and PD-L1 status, are predictive of recurrence, disease-free survival, and overall survival. In many malignancies, TME characteristics are also predictive of response to immunotherapy. As window of opportunity studies using neoadjuvant immunotherapy become more common and treatment guidelines incorporate TME features, accurate assessment of the pre-treatment TME using the biopsy specimen is critical. However, no study has thoroughly evaluated the correlation between the TMEs of the biopsy and resection specimens.

Methods

We conducted a retrospective analysis of patients with stage I–III CRC with matched biopsy and resection specimens. CD3+, CD4+, CD8+, and FoxP3+ lymphocyte populations at the center of tumor (CT) and invasive margin (IM) and tumor PD-L1 status in the biopsy and resection specimens were evaluated. TIL populations were compared using Mann–Whitney U tests or Student’s t tests and correlated using Pearson r.

Results

CD3+ and CD4+ densities were significantly higher in the CT of the biopsy relative to the resection specimen Comparing biopsy and resection specimens, no TIL population at either the CT or IM had a correlation coefficient > 0.5. Determining PD-L1 status based on biopsy tissue resulted in a sensitivity of 37.1%, specificity of 81.4%, and accuracy of 61.5%.

Conclusions

These findings demonstrate significant discordance between the TME of the biopsy and resection specimens. Caution should be used when basing treatment decisions on pre-treatment endoscopic biopsy findings and when interpreting changes in the TME between pre-treatment biopsy and resection specimens after neoadjuvant therapy.

Electronic supplementary material

The online version of this article (10.1007/s00262-020-02784-5) contains supplementary material, which is available to authorized users.

Current status on microsatellite instability, prognosis and adjuvant therapy in colon cancer: A nationwide survey of medical oncologists, colorectal surgeons and gastrointestinal pathologists

BACKGROUND

There is significant variation in attitude both towards the role of microsatellite instability (MSI) in predicting prognosis, and towards its role in guiding which Stage II colon cancer patients may benefit from adjuvant chemotherapy.

AIM

To examine the current status of specialist attitudes towards MSI in guiding prognosis and adjuvant therapy in stage II colon cancer.

METHODS

The Pathology in Colon Cancer, Prognosis and Uptake of Adjuvant Therapy (PiCC UP) Australia and New Zealand questionnaire was distributed to colorectal surgeons, medical oncologists and pathologists after institutional board approval. A 5-scale Likert score was used to assess attitudes towards 23 pathological features for prognosis and 18 features for adjuvant therapy. Data were analysed using a rating scale and graded response model in item response theory (IRT) on STATA (Stata MP, version 15; StataCorp LP).

RESULTS

164 specialists (45 oncologists, 86 surgeons and 33 pathologists) participated. 80.5% regularly attended colorectal multidisciplinary team (MDT) meetings. 89.63% and 59.26% of specialists reported that MSI status was likely or definitely to influence prognosis in colon cancer and recommendations for adjuvant therapy in Stage II colon cancer respectively. IRT modelling was achieved in 17 pathological features for prognosis. MSI IRT score was 4.47 (95% CI: 4.05-4.68). IRT modelling was achieved in 10 pathological features for adjuvant therapy. MSI IRT score was 3.62 (2.89-4.15). MSI ranked 10 (of 17) in order of importance in determining prognosis and ranked three (of 10) in guiding adjuvant therapy.

CONCLUSION

MSI status is considered an important biomarker when selecting patients for adjuvant therapy in Stage II colon cancer. MSI is also considered useful in prognostication of colon cancer. MSI status was ranked similar to the tumour grade of differentiation and the presence of perineural invasion.

Early stage colon cancer: Current treatment standards, evolving paradigms, and future directions

Colon cancer continues to be one of the leading causes of mortality and morbidity throughout the world despite the availability of reliable screening tools and effective therapies. The majority of patients with colon cancer are diagnosed at an early stage (stages I to III), which provides an opportunity for cure. The current treatment paradigm of early stage colon cancer consists of surgery followed by adjuvant chemotherapy in a select group of patients, which is directed at the eradication of minimal residual disease to achieve a cure. Surgery alone is curative for the vast majority of colon cancer patients. Currently, surgery and adjuvant chemotherapy can achieve long term survival in about two-thirds of colon cancer patients with nodal involvement. Adjuvant chemotherapy is recommended for all patients with stage III colon cancer, while the benefit in stage II patients is not unequivocally established despite several large clinical trials. Contemporary research in early stage colon cancer is focused on minimally invasive surgical techniques, strategies to limit treatment-related toxicities, precise patient selection for adjuvant therapy, utilization of molecular and clinicopathologic information to personalize therapy and exploration of new therapies exploiting the evolving knowledge of tumor biology. In this review, we will discuss the current standard treatment, evolving treatment paradigms, and the emerging biomarkers, that will likely help improve patient selection and personalization of therapy leading to superior outcomes.

Genomic Alterations and Their Implications on Survival in Nonmetastatic Colorectal Cancer: Status Quo and Future Perspectives

The selection of treatment according to genomic alterations is a standard approach in metastatic colorectal cancer but is only starting to have an impact in the earlier stages of the disease. The status if genes like KRAS, BRAF, and MMR has substantial survival implications, and concerted research efforts have revolutionized treatment towards precision oncology. In contrast, a genomic-based approach has not changed the adjuvant setting after curative tumor-resection in the daily routine so far. This review focuses on the current knowledge regarding prognostic and predictive genomic biomarkers in patients with locally advanced nonmetastasized colorectal cancer. Furthermore, we provide an outlook on future challenges for a personalized adjuvant treatment approach in patients with colorectal cancer.

Clinical significance of MLH1/MSH2 for stage II/III sporadic colorectal cancer

BACKGROUND

The development of colorectal cancer (CRC) is a complicated multistep process that involves an accumulation of mutations in tumor suppressor genes and oncogenes. In the process of DNA replication, base mismatch often occurs due to various factors leading to abnormal expression of mismatch repair genes (MMR), among which MLH1 and MSH2 are the most important. Recently, numerous studies indicated that MLH1/MSH2 phenotype is associated with CRC. We wanted to elucidate the role of MLH1/MSH2 in the prediction and prognosis of CRC through long-term clinical observation.

AIM

To evaluate the prognostic and predictive significance of MLH1/MSH2 in patients with stage II-III CRC using immunohistochemical analysis and GeneScan.

METHODS

Specimens from 681 patients with CRC (395 stage II and 286 stage III, 387 males and 294 females) who underwent curative surgical resection from 2013 to 2016 were tested. Immunohistochemistry was used to analyze MMR status and the microsatellite status of 133 patients was determined by GeneScan analysis.

RESULTS

Five hundred and fifty (80.76%) patients were MLH1/MSH2 positive and 131 (19.24%) were negative by immunohistochemistry. MLH1/MSH2-positive tumors were significantly more frequent in the colon than in the rectum, and had poor differentiation and less mucin production (P < 0.05). Patients of different groups did not differ in terms of age, gender, tumor size, tumor stage, lymphocytic infiltration, or circumscribed margin. MLH1/MSH2-negative patients had a more favorable OS than MLH1/MSH2-positive patients (P < 0.001). Univariate and multivariate analyses demonstrated MLH1/MSH2 expression as an independent prognostic and predictive factor for stage II/III CRC. MLH1/MSH2 expression was a strong prognostic factor in all patients [P < 0.001, hazard ratio (HR) = 4.064, 95%CI: 2.241–7.369]. Adjuvant chemotherapy had a greater correlation with survival advantage in MLH1/MSH2-negative patients with stage III disease (P < 0.001, HR = 7.660, 95%CI: 2.974–15.883). However, patients with stage II disease or MLH1/MSH2-positive patients with stage III disease did not benefit from adjuvant chemotherapy. GeneScan analysis demonstrated that among 133 patients, 105 (78.95%) were microsatellite stable, and 28 (21.05%) had microsatellite instability (MSI), including 18 (13.53%) with high MSI and 10 (7.52%) with low MSI. This is consistent with the immunohistochemical results.

CONCLUSION

MLH1/MSH2 phenotype constitutes a pathologically and clinically distinct subtype of sporadic CRC. MLH1/MSH2 is an independent prognostic and predictive factor for outcome of stage II-III CRC.