Consequences of testing for mismatch repair deficiency of colorectal cancer in clinical practice

INTRODUCTION

Mismatch repair deficiency (dMMR) can be found in Lynch syndrome (LS)-associated colorectal carcinoma and in 15% of sporadic colorectal cancer (CRC). Outcome of MMR-deficiency testing is important for surgical decisions as extended colectomy is recommended in young LS-patients with CRC. Moreover, the finding of a dMMR tumour has consequences for the choices of adjuvant chemotherapy as MMR-deficient CRC is resistant to 5-fluorouracil (5-FU) monotherapy. Aims of our study are to evaluate whether MMR-deficiency testing leads to (1) identification of LS, (2) change in surgical treatment and (3) adjustment of systemic therapy in patients with dMMR CRC.

METHODS

We performed a multicentre, retrospective study, in a community hospital and a University Medical Centre. We included all CRC-patients between 2012 and 2016 who were tested for microsatellite instability. We collected clinical data such as gender, age, referral to clinical geneticist, surgical procedure and choice of chemotherapy.

RESULTS

We analysed 225 CRCs. Twenty-four (10.7%) of 225 CRC were MMR-deficient. Of the 24 patients with dMMR CRC, 18 (75%) were referred to the clinical geneticist and in nine (37%) patients a MMR mutation was identified. In one (4%) of the 24 patients, a subtotal colectomy was performed. In seven (35%) out of 20 MMR deficient patients, the chemotherapy regimen was adjusted.

CONCLUSIONS

The finding of a dMMR CRC had consequences for decisions on chemotherapy in a relative high proportion of patients. We recommend testing in all patients with CRC independent of age at diagnosis, as proper treatment decisions and genetic counselling are very important.

Renal cancer and pneumothorax risk in Birt-Hogg-Dubé syndrome; an analysis of 115 FLCN mutation carriers from 35 BHD families

Background:

Birt–Hogg–Dubé (BHD) syndrome is an autosomal dominant condition caused by germline FLCN mutations, and characterised by fibrofolliculomas, pneumothorax and renal cancer. The renal cancer risk, cancer phenotype and pneumothorax risk of BHD have not yet been fully clarified. The main focus of this study was to assess the risk of renal cancer, the histological subtypes of renal tumours and the pneumothorax risk in BHD.

Methods:

In this study we present the clinical data of 115 FLCN mutation carriers from 35 BHD families.

Results:

Among 14 FLCN mutation carriers who developed renal cancer 7 were <50 years at onset and/or had multifocal/bilateral tumours. Five symptomatic patients developed metastatic disease. Two early-stage cases were diagnosed by surveillance. The majority of tumours showed characteristics of both eosinophilic variants of clear cell and chromophobe carcinoma. The estimated penetrance for renal cancer and pneumothorax was 16% (95% minimal confidence interval: 6–26%) and 29% (95% minimal confidence interval: 9–49%) at 70 years of age, respectively. The most frequent diagnosis in families without identified FLCN mutations was familial multiple discoid fibromas.

Conclusion:

We confirmed a high yield of FLCN mutations in clinically defined BHD families, we found a substantially increased lifetime risk of renal cancer of 16% for FLCN mutation carriers. The tumours were metastatic in 5 out of 14 patients and tumour histology was not specific for BHD. We found a pneumothorax risk of 29%. We discuss the implications of our findings for diagnosis and management of BHD.

Expanding CEP290 mutational spectrum in ciliopathies

Ciliopathies are an expanding group of rare conditions characterized by multiorgan involvement, that are caused by mutations in genes encoding for proteins of the primary cilium or its apparatus. Among these genes, CEP290 bears an intriguing allelic spectrum, being commonly mutated in Joubert syndrome and related disorders (JSRD), Meckel syndrome (MKS), Senior-Loken syndrome and isolated Leber congenital amaurosis (LCA). Although these conditions are recessively inherited, in a subset of patients only one CEP290 mutation could be detected. To assess whether genomic rearrangements involving the CEP290 gene could represent a possible mutational mechanism in these cases, exon dosage analysis on genomic DNA was performed in two groups of CEP290 heterozygous patients, including five JSRD/MKS cases and four LCA, respectively. In one JSRD patient, we identified a large heterozygous deletion encompassing CEP290 C-terminus that resulted in marked reduction of mRNA expression. No copy number alterations were identified in the remaining probands. The present work expands the CEP290 genotypic spectrum to include multiexon deletions. Although this mechanism does not appear to be frequent, screening for genomic rearrangements should be considered in patients in whom a single CEP290 mutated allele was identified.

No association between the Arg201Gly polymorphism of the DCC gene and colorectal cancer

BACKGROUND AND AIMS

In one small study, the DCC Arg201Gly polymorphism has been observed more frequently in colorectal cancer cases compared with controls. We wondered whether these results could be replicated in a much larger study.

METHODOLOGY

The DCC Arg201 Gly polymorphism was genotyped in 625 unselected Caucasian colorectal cancer patients and 220 controls. Association analysis was used to search for a difference between patients and controls. Subgroup analyses were performed for site of tumour, gender, age at diagnosis, family history of colorectal cancer and modified Dukes classification.

RESULTS

The association analyses revealed no difference in Arg201Gly genotype frequency between patients and controls, neither overall nor for different subgroups according to site of tumour, gender, age at diagnosis, family history of colorectal cancer and modified Dukes classification.

CONCLUSION

No association was observed between the Arg201Gly polymorphism of DCC and colorectal cancer risk.

Genes other than BRCA1 and BRCA2 involved in breast cancer susceptibility

This review focuses on genes other than the high penetrance genes BRCA1 and BRCA2 that are involved in breast cancer susceptibility. The goal of this review is the discovery of polymorphisms that are either associated with breast cancer or that are in strong linkage disequilibrium with breast cancer causing variants. An association with breast cancer at a 5% significance level was found for 13 polymorphisms in 10 genes described in more than one breast cancer study. Our data will help focus on the further analysis of genetic polymorphisms in populations of appropriate size, and especially on the combinations of such polymorphisms. This will facilitate determination of population attributable risks, understanding of gene-gene interactions, and improving estimates of genetic cancer risks.

Outcome after laparoscopic cholecystotomy and cholecystectomy in children with symptomatic cholecystolithiasis: a preliminary report

Laparoscopic cholecystectomy (LCE) has become the procedure of choice for symptomatic gallstones in children. However, there is concern about the disadvantages of cholecystectomy. Numerous postoperative symptoms and a possible correlation of the procedure with a higher incidence of right-sided colon carcinoma have been described. Therefore, it has been suggested to remove the gallstones via a cholecystotomy, leaving the gallbladder in place. This is the first report on the functional and symptomatic outcome of laparoscopic cholecystotomy (LCO) versus LCE in a consecutive series of children. A follow-up study of all children who underwent surgery for symptomatic gallstone disease from 1993 to 1999 was performed. Nine underwent LCO and 8 standard LCE. The procedure was chosen according to the preference of the surgeon. Patients and parents underwent a standardized follow-up interview. The intensitiy of six gastrointestinal symptoms was graded from 0 to 3. The patients and parents scored the symptomatic outcome using a 100-point visual analogue scale. There were no intraoperative complications. Bleeding of a port site required suturing in 1 patient after LCO, and fever with a further uneventful course occurred in another after LCE. The mean duration of hospital stay was 3.0 days after LCO and 2.4 days after LCE. In 1 patient a missed gallstone was identified 4 weeks after LCO. The patient underwent LCE with a further uneventful course. At follow-up (mean 20.7 months after LCO, 28.3 months after LCE, P = n.s.) there was a tendency toward a lower incidence of symptoms after LCO. Symptoms were reported by 3 of 8 patients after LCO and 5 of 8 after LCE. The mean score of the symptomatic outcome was not statistically different. All patients with LCO were free of stones on ultrasound examination with normal contraction of the gallbladder. LCO thus represents an alternative approach. We consider LCO for children with symptomatic cholecystolithiasis before the onset of puberty. However, data on the long-term outcome from larger series are mandatory before a general recommendation can be given.

Comparison of several indium-111 ligands in labeling blood cells: effect of diethylpyrocarbonate and CO2

The effect of oxine sulfate, oxine sulfonate, tropolone, and Merc (2 mercaptopyridine-1-oxide) were compared with oxine, with respect to their capability of labeling blood cells when complexed to indium-111 (111In). Indium-111 oxine sulfate performed similarly to [111In]oxine with regard to cell labeling capability. Indium-111 oxine sulfonate had no labeling ability. Indium-111 tropolone and Merc were not superior to [111In]oxine as cell labeling agents. Carbon dioxide (CO2) and a CO2 generating compound, diethyl pyrocarbonate, dramatically improved the cell labeling ability in plasma of [111In]tropolone and Merc. In the case of oxine, this improvement was less distinct. Theoretical aspects of the CO2 cell labeling stimulating effect are discussed in terms of intra- and extracellular transferrin and lactoferrin iron (indium) binding capacity. Indium-111 tropolone behaved favorably with respect to inhibition of leukocyte migration, compared with oxine and Merc. Combined with the property of easy cell labeling and good solubility in water, also in the complexed state, tropolone must be regarded as the most suitable cell labeling ligand.

A motility test of leukocytes under agar

A migration test under agar for leukocytes was developed. Leukocytes moved quite a distance under anaerobic Blood Agar Base (blood agar), a Gibco product. Migration on stained and coloured plates was visualized by projection with a profile projector, making the use of a light microscope superfluous. A migration index was defined. Reproducibility was good enough to allow paired comparisons of leukocyte populations subjected to different treatments. Migration was the result of spontaneous and chemotactically directed migration. Cell-labelling complexes as 111In-oxinate and 111In-tropolonate--ligand concentration 3.5 micrograms/mL in the ultimate cell preparation--did not affect leukocyte migration. 111In-pyrithionate (mercapto pyridine-N-oxide) significantly impaired cell motility. The motility test described could be used as retrospective analysis in abscess localization studies using 111In labelled leukocytes.