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Hereditary Cancer in Clinical Practice May 2024Colorectal cancers (CRCs) in the Lynch syndromes have been assumed to emerge through an accelerated adenoma-carcinoma pathway. In this model adenomas with deficient...
BACKGROUND
Colorectal cancers (CRCs) in the Lynch syndromes have been assumed to emerge through an accelerated adenoma-carcinoma pathway. In this model adenomas with deficient mismatch repair have an increased probability of acquiring additional cancer driver mutation(s) resulting in more rapid progression to malignancy. If this model was accurate, the success of colonoscopy in preventing CRC would be a function of the intervals between colonoscopies and mean sojourn time of detectable adenomas. Contrary to expectations, colonoscopy did not decrease incidence of CRC in the Lynch syndromes and shorter colonoscopy intervals have not been effective in reducing CRC incidence. The prospective Lynch Syndrome Database (PLSD) was designed to examine these issues in carriers of pathogenic variants of the mis-match repair (path_MMR) genes.
MATERIALS AND METHODS
We examined the CRC and colorectal adenoma incidences in 3,574 path_MLH1, path_MSH2, path_MSH6 and path_PMS2 carriers subjected to regular colonoscopy with polypectomy, and considered the results based on sojourn times and stochastic probability paradigms.
RESULTS
Most of the path_MMR carriers in each genetic group had no adenomas. There was no association between incidences of CRC and the presence of adenomas. There was no CRC observed in path_PMS2 carriers.
CONCLUSIONS
Colonoscopy prevented CRC in path_PMS2 carriers but not in the others. Our findings are consistent with colonoscopy surveillance blocking the adenoma-carcinoma pathway by removing identified adenomas which might otherwise become CRCs. However, in the other carriers most CRCs likely arised from dMMR cells in the crypts that have an increased mutation rate with increased stochastic chaotic probabilities for mutations. Therefore, this mechanism, that may be associated with no or only a short sojourn time of MSI tumours as adenomas, could explain the findings in our previous and current reports.
PubMed: 38741120
DOI: 10.1186/s13053-024-00279-3 -
Frontiers in Oncology 2024Early-onset colorectal cancer (CRC), defined as diagnosis before age 50, has increased in recent decades. Although more often diagnosed at advanced stage, associations...
BACKGROUND
Early-onset colorectal cancer (CRC), defined as diagnosis before age 50, has increased in recent decades. Although more often diagnosed at advanced stage, associations with other histological and molecular markers that impact prognosis and treatment remain to be clarified. We conducted a systematic review and meta-analysis concerning the prevalence of prognostic and predictive tumor markers for early- vs. late-onset CRC, including oncogene mutations, microsatellite instability (MSI), and emerging markers including immune cells and the consensus molecular subtypes.
METHODS
We systematically searched PubMed for original research articles published between April 2013-January 2024. Included studies compared the prevalence of tumor markers in early- vs. late-onset CRC. A meta-analysis was completed and summary odds ratios (ORs) with 95% confidence intervals (CIs) were obtained from a random effects model via inverse variance weighting. A sensitivity analysis was completed to restrict the meta-analysis to studies that excluded individuals with Lynch syndrome, a hereditary condition that influences the distribution of tumor markers for early-onset CRC.
RESULTS
In total, 149 articles were identified. Tumors from early-onset CRC are less likely to include mutations in (OR, 95% CI: 0.91, 0.85-0.98), (0.63, 0.51-0.78), (0.70, 0.58-0.84), and (0.88, 0.78-1.00) but more likely to include mutations in (1.68, 1.04-2.73) and (1.34, 1.24-1.45). After limiting to studies that excluded Lynch syndrome, the associations between early-onset CRC and (0.77, 0.64-0.92) and mutation (0.81, 0.67-0.97) were attenuated, while an inverse association with mutation was also observed (0.88, 0.78-0.99). Early-onset tumors are less likely to develop along the CpG Island Methylator Phenotype pathway (0.24, 0.10-0.57), but more likely to possess adverse histological features including high tumor grade (1.20, 1.15-1.25), and mucinous (1.22, 1.16-1.27) or signet ring histology (2.32, 2.08-2.57). A positive association with MSI status (1.31, 1.11-1.56) was also identified. Associations with immune markers and the consensus molecular subtypes are inconsistent.
DISCUSSION
A lower prevalence of mutations in and is consistent with extended survival and superior response to targeted therapies for metastatic disease. Conversely, early-onset CRC is associated with aggressive histological subtypes and and mutations, which may serve as therapeutic targets.
PubMed: 38737895
DOI: 10.3389/fonc.2024.1349572 -
HGG Advances May 2024Approximately 20% of breast cancer cases are attributed to increased family risk; yet variation in BRCA1/2 can only explain 20-25% of cases. Historically, only single...
Targeted sequencing for hereditary breast and ovarian cancer in BRCA1/2-negative families from the Lynch Memorial Biobank reveals complex genetic architecture and phenocopies.
Approximately 20% of breast cancer cases are attributed to increased family risk; yet variation in BRCA1/2 can only explain 20-25% of cases. Historically, only single gene or single variant testing were common in at-risk family members, and further sequencing studies were rarely offered after negative results. In this study, we applied an efficient and inexpensive targeted sequencing approach to provide molecular diagnoses in 245 human samples representing 134 BRCA mutation negative (BRCAX) hereditary breast and ovarian cancer (HBOC) families recruited from 1973-2019 by Dr. Henry Lynch. Sequencing identified 391 variants, which were functionally annotated and ranked based on their predicted clinical impact. Known pathogenic CHEK2 breast cancer variants were identified in five BRCAX families in this study. While BRCAX was an inclusion criterion for this study, we still identified a pathogenic BRCA2 variant (p.Met192ValfsTer13) in one family. A portion of BRCAX families could be explained by other hereditary cancer syndromes that increase HBOC risk: Li-Fraumeni Syndrome (gene: TP53) and Lynch Syndrome (gene: MSH6). Interestingly, many families carried additional Variants of Undetermined Significance (VOUSs) that may further modify phenotypes of syndromic family members. Ten families carried more than one potential VOUS suggesting the presence of complex multi-variant families. Overall, nine BRCAX HBOC families in our study may be explained by known likely-pathogenic/pathogenic variants, and six families carried potential VOUSs, which require further functional testing. To address this, we developed a functional assay where we successfully re-classified one family's PMS2 VOUS as benign.
PubMed: 38734904
DOI: 10.1016/j.xhgg.2024.100306 -
Diagnostics (Basel, Switzerland) Apr 2024The immunohistochemical assessment of mismatch repair (MMR) proteins represents a pivotal screening tool for identifying Lynch syndrome (LS)-related cancers, as the loss...
The immunohistochemical assessment of mismatch repair (MMR) proteins represents a pivotal screening tool for identifying Lynch syndrome (LS)-related cancers, as the loss of their expression often indicates MMR dysfunction associated with genetic or epigenetic alterations. Frequently, LS-related colorectal cancers present germline pathogenic variants in the or genes, which result in the simultaneous immunohistochemical loss of MLH1 and PMS2 or MSH2 and MSH6 proteins expression, respectively. Less commonly observed is the single involvement of the MSH6 or PMS2 proteins expression, indicative of the presence of germline pathogenic variants in the corresponding genes. Extremely rarely reported are the null immunohistochemistry phenotypes represented by the complete loss of expression of all MMR proteins. The molecular mechanisms contributing to the raising of this latter uncommon immunohistochemical phenotype are derived from the combination of pathogenic germline variants in MMR genes with the somatic hypermethylation of the gene promoter. This study focuses on elucidating the molecular cascade leading to the development of the null immunohistochemical phenotype, providing valuable insights into understanding the sequential molecular events driving the LS-associated tumorigenesis, which may have pivotal implications in the clinical management of patients with LS-related cancers.
PubMed: 38732303
DOI: 10.3390/diagnostics14090888 -
Frontiers in Oncology 2024Lynch syndrome (LS) is an autosomal dominant multi-organ cancer syndrome with a high lifetime risk of cancer. The number of cumulative colorectal adenomas in LS does not...
BACKGROUND
Lynch syndrome (LS) is an autosomal dominant multi-organ cancer syndrome with a high lifetime risk of cancer. The number of cumulative colorectal adenomas in LS does not generally exceed ten, and removal of adenomas via routine screening minimizes the cancer burden. However, abnormal phenotypes may mislead initial diagnosis and subsequently cause suboptimal treatment.
AIM
Currently, there is no standard guide for the care of multiple colorectal adenomas in LS individuals. We aimed to shed insight into the molecular features and reasons for multiplicity of adenomas in LS patients.
METHODS
We applied whole exome sequencing on nine adenomas (ten samples) and three assumed primary carcinomas (five samples) of an LS patient developing the tumors during a 21-year follow-up period. We compared the findings to the tumor profiles of two additional LS cases ascertained through colorectal tumor multiplicity, as well as to ten adenomas and 15 carcinomas from 23 unrelated LS patients with no elevated adenoma burden from the same population. As LS associated cancers can arise via several molecular pathways, we also profiled the tumors for CpG Island Methylator Phenotype (CIMP), and LINE-1 methylation.
RESULTS
All tumors were microsatellite unstable (MSI), and MSI was present in several samples derived from normal mucosa as well. Interestingly, frequent frameshift variants in were shared among substantial number of the tumors of our primary case and the tumors of LS cases with multiple tumors but almost absent in our control LS cases. The variants were completely absent in the normal tissue, indicating tumor-associated mutational hotspots. The status correlated with the mutational signature SBS96. Contrary to LS tumors from the reference set with no elevated colorectal tumor burden, the somatic variants occurred significantly more frequently at C>T in the CpG context, irrespective of CIMP or LINE-1 status, potentially indicating other, yet unknown methylation-related mechanisms. There were no signs of somatic mosaicism affecting the MMR genes. Somatic variants in and were unique to each tumor.
CONCLUSION
Frequent somatic hot spot variants combined with SBS96 signature and increased tendency to DNA methylation may contribute to tumor multiplicity in LS.
PubMed: 38725616
DOI: 10.3389/fonc.2024.1378392 -
Journal of Gynecologic Oncology May 2024The efficacy of pembrolizumab in patients with microsatellite instability (MSI)-high cancers has been reported; however, the differences in efficacy according to the...
OBJECTIVE
The efficacy of pembrolizumab in patients with microsatellite instability (MSI)-high cancers has been reported; however, the differences in efficacy according to the subtypes of MSI-high endometrial cancers (ECs) remain unclear. MSI-high ECs are classified into at least 3 groups based on their molecular characteristics: hypermethylated, Lynch-like syndrome (LLS)-associated, and Lynch syndrome (LS)-associated cancers. This study aimed to investigate whether the efficacy of pembrolizumab differs among these 3 groups, and if so, whether EPM2AIP1 immunohistochemistry (IHC), which correlates with promoter methylation, can be used to rule out methylation cases.
METHODS
This study included 12 patients with MSI-high EC who received pembrolizumab treatment. Patients were categorized into 3 groups based on methylation analysis and the Amsterdam Criteria: hypermethylated (sporadic [SP]), LLS-associated, and LS-associated. Patients' medical records were retrospectively reviewed, and the efficacy of treatment was evaluated based on the response rate using the Response Evaluation Criteria in Solid Tumors version 1.1.
RESULTS
The overall response rate was 75% (3/4) in the SP group, while it was 100% including one complete response patient in the LLS-associated and the LS-associated group, respectively. The sensitivity and positive predictive value of EPM2AIP1 IHC for methylation were 100% and 66.7%, respectively.
CONCLUSION
Pembrolizumab may be more effective in LLS and LS-associated groups. EPM2AIP1 IHC was less predictive than methylation analysis; however, it may be useful for ruling out methylation cases due to its high sensitivity. Further studies are needed to determine whether EPM2AIP1 IHC can predict pembrolizumab efficacy.
PubMed: 38725237
DOI: 10.3802/jgo.2024.35.e103 -
Translational Gastroenterology and... 2024Deficient mismatch repair (MMR) leading to microsatellite instability (MSI) in tumors is thought to be present in over 15% of colorectal cancer (CRC) cases. Testing CRC...
BACKGROUND
Deficient mismatch repair (MMR) leading to microsatellite instability (MSI) in tumors is thought to be present in over 15% of colorectal cancer (CRC) cases. Testing CRC for MSI has traditionally been recommended following the fulfillment of clinical criteria. However, the performance of clinical criteria, especially the family history, as a selection tool for MSI screening in CRC is questionable.
METHODS
We retrospectively investigated the incidence of high degree MSI (MSI-H) tumors in an unselected population of CRC patients and compared its prevalence between individuals with and without family history of cancers within the spectrum of MSI-H tumors as defined in the revised Bethesda criteria.
RESULTS
The study population included 274 patients, 70 with positive and 204 without family history of MSI-H tumors with complete data including findings from MSI analysis. The overall incidence of MSI-H CRC was 18.98%. There was no statistically significant difference in the incidence of MSI-H CRC amongst both groups. The sensitivity and specificity of family history with regard to the presence of an MSI-H tumor in this collective was 36.5% and 77.5%, respectively.
CONCLUSIONS
A relevant number of cases with high MSI-H CRC may be missed secondary to screening based on clinical criteria like family history alone. Thus, systematic screening independent of clinical characteristics, especially family history of cancer should be recommended in all cases with CRC.
PubMed: 38716207
DOI: 10.21037/tgh-23-71 -
The Journal of Clinical Investigation May 2024Splicing factor mutations are common in myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML), but how they alter cellular functions is unclear. We show that...
Splicing factor mutations are common in myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML), but how they alter cellular functions is unclear. We show that the pathogenic SRSF2P95H/+ mutation disrupts the splicing of mitochondrial mRNAs, impairs mitochondrial complex I function, and robustly increases mitophagy. We also identified a mitochondrial surveillance mechanism by which mitochondrial dysfunction modifies splicing of the mitophagy activator PINK1 to remove a poison intron, increasing the stability and abundance of PINK1 mRNA and protein. SRSF2P95H-induced mitochondrial dysfunction increased PINK1 expression through this mechanism, which is essential for survival of SRSF2P95H/+ cells. Inhibition of splicing with a glycogen synthase kinase 3 inhibitor promoted retention of the poison intron, impairing mitophagy and activating apoptosis in SRSF2P95H/+ cells. These data reveal a homeostatic mechanism for sensing mitochondrial stress through PINK1 splicing and identify increased mitophagy as a disease marker and a therapeutic vulnerability in SRSF2P95H mutant MDS and AML.
PubMed: 38713535
DOI: 10.1172/JCI175619 -
BioRxiv : the Preprint Server For... Apr 2024Splicing factor mutations are common in myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML), but how they alter cellular functions is unclear. We show that...
Splicing factor mutations are common in myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML), but how they alter cellular functions is unclear. We show that the pathogenic mutation disrupts the splicing of mitochondrial mRNAs, impairs mitochondrial complex I function, and robustly increases mitophagy. We also identified a mitochondrial surveillance mechanism by which mitochondrial dysfunction modifies splicing of the mitophagy activator to remove a poison intron, increasing the stability and abundance of mRNA and protein. -induced mitochondrial dysfunction increased expression through this mechanism, which is essential for survival of cells. Inhibition of splicing with a glycogen synthase kinase 3 inhibitor promoted retention of the poison intron, impairing mitophagy and activating apoptosis in cells. These data reveal a homeostatic mechanism for sensing mitochondrial stress through splicing and identify increased mitophagy as a disease marker and a therapeutic vulnerability in mutant MDS and AML.
PubMed: 38712254
DOI: 10.1101/2023.06.25.546449 -
Hereditary Cancer in Clinical Practice May 2024Risk-reducing gynecological surgery (RRGS) is a prophylactic procedure that may be offered to BRCA1, BRCA2, and Lynch syndrome (LS) mutation carriers to reduce the risk...
BACKGROUND
Risk-reducing gynecological surgery (RRGS) is a prophylactic procedure that may be offered to BRCA1, BRCA2, and Lynch syndrome (LS) mutation carriers to reduce the risk of developing gynecological cancer. This study was conducted to better understand patients' information needs and evaluate how patients weigh different sources of information in their decision-making process surrounding RRGS.
METHODS
This study used a qualitative approach to understanding women's perspectives towards RRGS. Semi-structured interviews were conducted virtually with 8 women. Women offered RRGS between 35 and 70 years of age who are English-speaking and have an identifiable BRCA or LS mutation were included. Data from interviews was coded with constant comparative analysis to develop themes.
RESULTS
Of the eight women, six had selected to undergo either prophylactic hysterectomy or oophorectomy: 5 decided yes to RRGS; 1 decided no; 2 were undecided. Thematic analysis found that the key factors affecting women's decisions around prophylactic surgery were cancer risk, surgical menopause, and psychological readiness. To make an informed decision, women relied most heavily on information provided by healthcare professionals (e.g. doctors, genetic counselors) and family members with prior cancer experience. However, some women reported that they did not feel adequately informed enough to make a decision and identified COVID-19 as a significant barrier affecting access to information.
CONCLUSION
This qualitative study revealed the key sources of information influencing attitudes regarding RRGS and how women consulted different sources of information to reach a decision. Results underscore the need for greater attention to women's information needs in the context of psychological readiness, particularly amidst the pandemic. Research involving a larger sample size may help to better inform how support can be provided to individuals with BRCA and LS mutations considering RRGS.
PubMed: 38698439
DOI: 10.1186/s13053-024-00278-4