PTEN in colorectal cancer: a report on two Cowden syndrome patients

Gastrointestinal manifestations in PTEN hamartoma tumor syndrome

The PTEN hamartoma tumor syndrome (PHTS) is a heterogeneous set of multisystem disorders caused by germline pathogenic variants in the PTEN tumor suppressor gene. Manifestations include developmental anomalies and proliferative lesions. Evidence of involvement of the GI tract has accrued over time, leading to the incorporation of GI manifestations (multiple hamartomas, glycogenic acanthosis and colorectal cancer) into the diagnostic criteria. Polyps of the upper and lower GI tract are found in most adult patients and in a significant fraction of children. Polyps tend to be of mixed histology, with a predominance of hamartomas and ganglioneuromas. PHTS patients are also at increased risk of colorectal cancer, and surveillance by colonoscopy is advised starting at the age of 35-40 years. A number of additional manifestations, including eosinophilic gastrointestinal disorders, have been observed in few or single cases, and their association with PHTS has yet to be determined.

Revised Danish guidelines for the cancer surveillance of patients with Cowden Syndrome

INTRODUCTION

Cowden syndrome is a cancer predisposition syndrome caused by pathogenic variants in PTEN. The affected patients possess an increased risk of breast, thyroid, renal, colorectal, endometrial cancers as well as malignant melanoma. Thus prophylactic surveillance and follow up is crucial for these patients.

METHODS

A review of the literature including existing guidelines from the years 1996 until 2017 was carried out. In total, 2078 scientific papers were identified through database searches on Cowden syndrome. Among these, 11 manuscripts were included based on scientific relevance and quality. Expert consensus was reached to define management guidelines.

RESULTS

The literature revealed a high risk of cancer in specific organs for patients diagnosed with Cowden Syndrome. Alternative management guidelines were proposed and discussed.

CONCLUSIONS

Here we propose a revised set of management guidelines for patients with Cowden syndrome in Denmark to address the increased risk of various cancer types.

Incidence, clinical features and possible etiology of early onset (≤40 years) colorectal neoplasms

The aim of the study was to investigate the clinical features, including survival, of patients with colorectal malignancies developed at a very early age (≤40 years), together with possible factors involved in the pathogenesis of these rare neoplasms. The study took advantage of the existence of a specialized colorectal cancer Registry active from 1984. 57 patients met the criteria of early onset cancer; main epidemiological data, morphology, stage, familial aggregation, possible role of inheritance and survival were analyzed. Despite the relevant increase over time of all registered patients, joiningpoint analysis of crude incidence rate of early onset colorectal neoplasms revealed a certain stability of these tumors (EAPC: 2.4, CI 14-22) with a constant prevalence of the male sex. Stage at diagnosis did not show significant variations between early onset and maturity onset colorectal neoplasms. Hereditary as well as familial cases were significantly (P < 0.005 and 0.03) more frequent among patients with early onset tumors, although in the majority of them no specific etiological factor could be identified. Survival was more favorable in patients with early onset tumors, though this had to be attributed to the higher presence of some histological types in early onset cases. Survival was significantly more favorable for patients of all ages registered in the last decade. Incidence of early onset colorectal cancer was relatively stable between 1984 and 2008. A male preponderance was evident through the registration period. Hereditary and familial cases were significantly more frequent among early onset case. A well defined etiology could be observed in 16% of the cases (versus 2-3% in older individuals). Five-year survival showed a significant improvement over time.

Colonic manifestations of PTEN hamartoma tumor syndrome: Case series and systematic review

AIM: To investigate our clinical experience with the colonic manifestations of phosphatase and tensin homolog on chromosome ten (PTEN) hamartoma tumor syndrome (PHTS) and to perform a systematic literature review regarding the same.

METHODS: This study was approved by the appropriate institutional review board prior to initiation. A clinical genetics database was searched for patients with PHTS or a component syndrome that received gastrointestinal endoscopy or pathology interpretation at our center. These patient’s records were retrospectively reviewed for clinical characteristics (including family history and genetic testing), endoscopy results and pathology findings. We also performed a systematic review of the literature for case series of PHTS or component syndromes that reported gastrointestinal manifestations and investigations published after consensus diagnostic criteria were established in 1996. These results were compiled and reported.

RESULTS: Eight patients from our institution met initial inclusion criteria. Of these, 5 patients underwent 4.2 colonoscopies at mean age 45.8 ± 10.8 years. All were found to have colon polyps during their clinical course and polyp histology included adenoma, hyperplastic, ganglioneuroma and juvenile. No malignant lesions were identified. Two had multiple histologic types. One patient underwent colectomy due to innumerable polyps and concern for future malignant potential. Systematic literature review of PHTS patients undergoing endoscopy revealed 107 patients receiving colonoscopy at mean age 37.4 years. Colon polyps were noted in 92.5% and multiple colon polyp histologies were reported in 53.6%. Common polyp histologies included hyperplastic (43.6%), adenoma (40.4%), hamartoma (38.3%), ganglioneuroma (33%) and inflammatory (24.5%) polyps. Twelve (11.2%) patients had colorectal cancer at mean age 46.7 years (range 35-62). Clinical outcomes secondary to colon polyposis and malignancy were not commonly reported.

CONCLUSION: PHTS has a high prevalence of colon polyposis with multiple histologic types. It should be considered a mixed polyposis syndrome. Systematic review found an increased prevalence of colorectal cancer and we recommend initiating colonoscopy for colorectal cancer surveillance at age 35 years.

Epithelial-specific loss of PTEN results in colorectal juvenile polyp formation and invasive cancer

Cowden syndrome (CS) is a rare autosomal dominant cancer-prone disorder caused by germ-line mutation of the phosphatase and tensin homolog mutated on chromosome 10 (PTEN) tumor-suppressor gene. Affected patients commonly develop juvenile polyps, and show an elevated risk of developing colorectal cancers. The etiology of these peculiar polyps remains unclear, although previous work has suggested somatic PTEN alterations in the stroma of juvenile polyps. After a long latency period, we find epithelial-specific PTEN deletion to cause formation of juvenile polyps in the colorectum without stromal PTEN loss. More important, we find that these lesions closely recapitulate all of the characteristic histopathological features of juvenile polyps seen in patients with CS, including stromal alterations and dysplastic transformation to colorectal carcinoma. The stromal alterations we identify after epithelial-specific PTEN loss suggest that PTEN may be involved in altered epithelial-mesenchymal cross talk, which, in turn, predisposes to colorectal neoplasia and polyposis. Our transgenic model is the first to recapitulate colorectal juvenile polyposis in patients with CS. We conclude that stromal PTEN loss is not a prerequisite for the formation of juvenile polyps, and that colorectal juvenile polyps in CS are bona fide neoplastic precursor lesions.

Hamartomatous polyposis syndromes

Hamartomas are tumour-like malformations, consisting of disorganized normal tissues, typical of the site of tumour manifestation. Familial manifestation of hamartomatous polyps can be noted in juvenile polyposis syndrome (JPS), Peutz-Jeghers’ syndrome (PJS), hereditary mixed polyposis syndrome (HMPS) and PTEN hamartoma tumour syndrome (PHTS). All the aforementioned syndromes are inherited in an autosomal dominant manner and form a rather heterogenous group both in respect to the number and localization of polyps and the risk of cancer development in the alimentary tract and other organs. Individual syndromes of hamartomatous polyposis frequently manifest similar symptoms, particularly during the early stage of the diseases when in several cases their clinical pictures do not allow for differential diagnosis. The correct diagnosis of the disease using molecular methods allows treatment to be implemented earlier and therefore more effectively since it is followed by a strict monitoring of organs that manifest a predisposition for neoplastic transformation.

Role of SALL4 in the progression and metastasis of colorectal cancer

Background

Human cancer cells resemble stem cells in expression signatures leading them to share some features, most notably, self-renewal. A complex network of transcription factors and signaling molecules are required for continuance of this trait. SALL4 is a zinc finger transcriptional activator crucial for maintenance of self-renewal in stem cells; however, its expression level has not yet been elucidated in colorectal tumor cells. To determine this level and probable clinicopathological consequences, its expression was analyzed.

Methods

SALL4 expression in fresh tumoral and distant tumor-free tissues from 46 colorectal samples was compared by real-time polymerase chain reaction (PCR).

Results

Greater than a two-fold increase in SALL4 expression was detected in 87% of tumors vs. normal related tissues. SALL4 expression was significantly correlated with tumor cell metastasis to lymph nodes, especially in moderately-differentiated tumor samples (P < 0.05). Furthermore, higher levels of SALL4 mRNA expression were significantly associated with younger than older patients with tumor cells in stages I and II (P < 0.05).

Conclusions

These results indicate a relationship between SALL4 expression and tumor cell metastasis to lymph nodes and consequent advancement of tumors to advanced stages III and IV. Along with the promising evidence of its role in self-renewal in various cancers, SALL4 may have a role in progression, development and maintenance of colorectal cancers.

Is colorectal surveillance indicated in patients with PTEN mutations?

AIM

Patients with germline phosphatase and tensin homologue (PTEN) mutations develop hamartomatous lesions in several organs and are at increased risk of various malignancies. We assessed the lifetime risk of benign and malignant gastrointestinal lesions in patients with a proven PTEN mutation.

METHOD

Data on gender, mutation, dates of birth, last contact, and diagnosis, location and type of gastrointestinal lesions were collected from nine countries. The lifetime risk of gastrointestinal lesions was calculated by Kaplan-Meier methods.

RESULTS

A total of 156 patients (67 men, 43%) from 101 families with a PTEN mutation were included. Patients were born between 1928 and 2008. Benign gastrointestinal polyps were reported in 49 (31%) patients at a mean age of 38 years (range 18-62 years) and were most often hamartomas. Twenty-two (44%) patients had upper as well as lower gastrointestinal lesions, 14 (29%) had only colonic lesions and 13 (27%) had gastrointestinal lesions at unknown sites. The cumulative risk of developing benign gastrointestinal polyps was 70% at age 60. Four patients (two men) developed colorectal carcinoma at 53, 57, 59 and 62 years, respectively. The cumulative risk of developing colorectal carcinoma was 18% at age 60. Except for one carcinoid in the small intestine, no upper gastrointestinal cancers were observed.

CONCLUSION

Benign gastrointestinal lesions are common in PTEN mutation carriers, and a three- to four-fold increased lifetime risk of colorectal cancer compared with the general population may exist. Colorectal screening of patients with germline PTEN mutations is recommended, starting at age 40 years.