Role of oncogenic pathways and KRAS/BRAF mutations in the behavior of colon adenocarcinoma in renal transplant patients. Transplantation. 2012;93:509-517. [PMID: 22245873 DOI: 10.1097/TP.0b013e318242be46]

Contrast-enhanced US in Renal Transplant Complications: Overview and Imaging Features

Renal transplant is the first-line treatment of end-stage renal disease. The increasing number of transplants performed every year has led to a larger population of transplant patients. Complications may arise during the perioperative and postoperative periods, and imaging plays a key role in this scenario. Contrast-enhanced US (CEUS) is a safe tool that adds additional value to US. Contrast agents are usually administered intravenously, but urinary tract anatomy and complications such as stenosis or leak can be studied using intracavitary administration of contrast agents. Assessment of the graft and iliac vessels with CEUS is particularly helpful in identifying vascular and parenchymal complications, such as arterial or venous thrombosis and stenosis, acute tubular injury, or cortical necrosis, which can lead to graft loss. Furthermore, infectious and malignant graft involvement can be accurately studied with CEUS, which can help in detection of renal abscesses and in the differentiation between benign and malignant disease. CEUS is also useful in interventional procedures, helping to guide percutaneous aspiration of collections with better delimitation of the graft boundaries and to guide renal graft biopsies by avoiding avascular areas. Potential postprocedural vascular complications, such as pseudoaneurysm, arteriovenous fistula, or active bleeding, are identified with CEUS. In addition, newer quantification tools such as CEUS perfusion are promising, but further studies are needed to approve its use for clinical purposes. ©RSNA, 2024 Supplemental material is available for this article.

Colorectal Cancer after Kidney Transplantation: A Screening Colonoscopy Case-Control Study

The incidence of colorectal cancer in kidney transplant recipients has been previously reported with conflicting results. In this study, we investigated if the incidence of colorectal advanced neoplasms in kidney transplant recipients, evaluated with screening colonoscopy, was higher than in healthy individuals. One-hundred sixty kidney transplant recipients undergoing screening colonoscopy were compared with 594 age- and sex-matched healthy individuals. Advanced colorectal neoplasia was found in 22 patients (13.7%), including four patients (2.5%) with colorectal cancer. Compared with the healthy population, kidney transplant recipients did not have an increased risk of developing a colorectal cancer (OR 0.69; 95% CI 0.236–2.063, p = 0.688) although it developed at a younger age. In contrast, kidney transplant recipients had a higher risk of developing an advanced adenoma compared with the control group (OR 1.65; 95% CI 0.930–2.981, p = 0.04). In conclusion, kidney transplant recipients did not have an increased incidence of colorectal cancer compared with healthy population. However, transplant patients displayed a higher incidence of colorectal adenomas, suggesting that screening colonoscopy in kidney transplant recipients should be expanded to include even younger recipients (<50 years old).

Effect of immunosuppression in miRNAs from extracellular vesicles of colorectal cancer and their influence on the pre-metastatic niche

Colorectal cancer (CRC) occurs with more aggressiveness in kidney transplant recipients compared to the general population. Immunosuppressive therapy plays a crucial role in the development of post-transplant malignancy. Concretely, cyclosporine A (CsA) has intrinsic pro-oncologic properties, while several studies report a regression of cancer after the introduction of rapamycin (RAPA). However, their effect on the extracellular vesicle (EV) content from CRC cell lines and their relevance in the pre-metastatic niche have not yet been studied. Here, we investigated the effect of RAPA and CsA in EV-miRNAs from metastatic and non-metastatic CRC cell lines and the role of relevant miRNAs transferred into a pre-metastatic niche model. EV-miRNA profiles showed a significant upregulation of miR-6127, miR-6746-5p, and miR-6787-5p under RAPA treatment compared to CsA and untreated conditions in metastatic cell lines that were not observed in non-metastatic cells. From gene expression analysis of transfected lung fibroblasts, we identified 22 shared downregulated genes mostly represented by the histone family involved in chromatin organization, DNA packaging, and cell cycle. These results suggest that EV-miR-6127, miR-6746-5p and miR-6787-5p could be a potential epigenetic mechanism induced by RAPA therapy in the regulation of the pre-metastatic niche of post-transplant colorectal cancer.

Comprehensive Review on Colorectal Cancer and Transplant

Colorectal cancer (CRC) is a common malignancy worldwide. Some studies suggest that organ recipients are at a higher risk for CRC than the general population. The underlying transplant indications and their inherent risk factors for CRC may drive the variation in incidence rates that are seen in patients receiving different allografts. Recipients with cystic fibrosis are now recognized as a population at high risk for CRC at a young age. Transplant recipients have high mortality following a CRC diagnosis, even if it is detected at an early stage. Certain types of immunosuppression have been shown to accelerate cancer transformation and may contribute to the more aggressive phenotype seen in organ recipients. Given the high incidence and progressive nature of posttransplant CRC, shorter screening intervals with a modality that can detect early-stage polyps may be essential to prevent mortality. Future research is needed to better elucidate the role of immunosuppression in carcinogenesis. This comprehensive review examines CRC risk, screening, and management specific to organ transplant candidates and recipients.

Prevalence of advanced colorectal neoplasm after kidney transplantation: surveillance based on the results of screening colonoscopy

BACKGROUND AND AIM

The aim of this study was to determine whether the prevalence of advanced colorectal neoplasms increases in kidney transplant recipients and to define the appropriate duration for surveillance colonoscopy after kidney transplantation (TPL).

METHODS

Our study consisted of 248 kidney transplant patients who underwent a colonoscopy at Seoul National University Hospital from 1996 to 2008. For each patient, two or more age- and sex-matched controls were identified from a population of asymptomatic individuals.

RESULTS

Twenty (8.1 %) patients had advanced colonic neoplasms, including colorectal cancers (four patients, 1.6 %), after kidney TPL. A case-control study showed that the odds of advanced colonic neoplasms occurring in TPL patients were 2.3 times greater than in the matched subjects. In addition, TPL patients 50 years of age or older had an approximate 5.4-fold higher risk of developing advanced neoplasms than did the matched subjects (OR 5.370; 95 % CI 2.543-11.336; P < 0.001). Age and history of advanced neoplasms were associated with an increased risk of developing advanced neoplasms after TPL. The 5-year cumulative incidence rate of advanced neoplasms was 3.6 % in the 82 patients with normal or non-advanced adenomas detected via screening colonoscopy before TPL.

CONCLUSIONS

Colonoscopy is recommended for patients before and after kidney TPL, especially for those 50 years of age or older. Colonoscopy surveillance after TPL is warranted strictly according to the baseline risk stratification.

Diagnosis and treatment of rectal or anal carcinoma after renal transplantation

AIM: To report a case of rectal adenocarcinoma and a case of anal squamous cell carcinoma in situ after renal transplantation, and review the relevant literature.

METHODS: A case of squamous cell carcinoma in situ arising in a patient 2 years after renal transplantation and a case of rectal adenocarcinoma arising in a patient 14 years after renal transplantation were collected. The resected specimens were fixed in buffered formalin, paraffin-embedded, 4 μm-sectioned, and reviewed by two pathologists. Human papillary virus (HPV) and Epstein-Barr virus (EBV) were detected both in the adenocarcinoma and squamous carcinoma. K-ras and BRAF genes were sequenced in rectal adenocarcinoma to identify mutations.

RESULTS: The patient suffering from squamous cell carcinoma in situ was a 54-year-old female, with a history of mixed hemorrhoid for 30 years without obvious bleeding. The regimen of mycophenolate mofetil (MMF), prednisone (Pred) and tacrolimus was used to control rejection reactions. Six months after transplantation, the patients complained of intermittent painless hemorrhage. The diagnosis of mixed hemorrhoid was made by colonoscopy and conservative treatment was performed consequently for the next year. Since the hemorrhage became worse in the last month, hemorrhoid resection was performed. Squamous carcinoma in situ was diagnosed. There was no HPV or EBV infection. No adverse events occurred in the next 36-mo follow-up period. The patient suffering from rectal adenocarcinoma was a 39-year old male who complained of bloody stools for one year and aggravation for 1 mo. Colonoscopy revealed a space-occupying lesion localized in the rectum. He was diagnosed with renal failure 15 years ago and accepted renal allograft 14 years ago. MMF and Pred were used as the immunosuppressant for 12 years and stopped as the allograft lost its function 2 years ago. Anterior resection was performed and pathologic examination revealed poorly differentiated adenocarcinoma mixed with mucinous adenocarcinoma accompanied with numerous cancerous emboli and lymph node metastasis (pT3N2aM0). After 18 mo of follow-up, he suffered from abdominal relapse and hepatic metastasis. The lymphocytes infiltrating into the carcinoma were negative for EBER. Wild-type K-ras and BRAF were detected.

CONCLUSION: Bloody stools can be the fist sign of anal or rectal carcinoma. Immunosuppressive drugs may act as a pivotal enhancer during the pathogenesis of carcinoma. The patients sensitive to immunosuppression therapy and/or undergoing long-term immunosuppression therapy should be cautious of carcinoma.