1 / 62

CANCER GENETICS: IDENTIFICATION AND MANAGEMENT OF INDIVIDUALS WITH LYNCH SYNDROME

CANCER GENETICS: IDENTIFICATION AND MANAGEMENT OF INDIVIDUALS WITH LYNCH SYNDROME HENRY T. LYNCH, MD Creighton University School of Medicine Omaha, Nebraska. Hereditary Cancer Syndromes: Nuts and Bolts. Family history; Hereditary cancer syndrome diagnosis; Genetic counseling;

dixie
Télécharger la présentation

CANCER GENETICS: IDENTIFICATION AND MANAGEMENT OF INDIVIDUALS WITH LYNCH SYNDROME

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. CANCER GENETICS: IDENTIFICATION AND MANAGEMENT OF INDIVIDUALS WITH LYNCH SYNDROME HENRY T. LYNCH, MD Creighton University School of Medicine Omaha, Nebraska

  2. Hereditary Cancer Syndromes:Nuts and Bolts • Family history; • Hereditary cancer syndrome diagnosis; • Genetic counseling; • DNA studies; • Highly targeted surveillance/management; • Extend to all at-risk relatives; • Physician education; • Research problem of discrimination (insurance, • employment); • Strategies for wide-spread interest of familial • cancer approach to cancer control, malpractice, • molecular genetics, other.

  3. Patient’s Modified Nuclear Pedigree

  4. Why Pursue Cancer of All Anatomic Sites? • Pertinent for any hereditary cancer syndrome diagnosis; • Most identified by pattern of cancer expression, e.g.: • breast and ovary (HBOC syndrome); • CRC, endometrium, ovary, others (Lynch syndrome); • sarcomas, breast, brain, multiple others in SBLA (Li- Fraumeni syndrome); • medullary thyroid carcinoma and pheochromocytoma (MEN-2a and MEN-2b); • melanoma and pancreatic cancer with CDKN2A (p16) mutation (FAMMM syndrome); • diffuse gastric cancer and lobular breast cancer with CDH1 mutation (HDGC syndrome); ...and the list goes on.

  5. Colorectal Cancer • Worldwide estimates for colorectal cancer during 2008*: • Incidence – 1,233,711 • Mortality – 608,644 • Worldwide estimates for familial/hereditary CRC during 2008*: • Lynch syndrome 3-5% of all CRC 37,011-61,686 • FAP <1% of all CRC <12,337 • Familial 20% of all CRC 246,742 • *GLOBOCAN. The International Agency for Research • on Cancer web site. URL: http://www.iarc.fr/

  6. Familial/Hereditary CRC in US Annual CRC incidence in US: 142,570 Lynch syndrome 3-5% of all CRC 4,277 - 7,129 FAP <1% of all CRC <1,426 Familial 20% of all CRC 28,514 Jemal et al. CA Cancer J Clin 60:277-300,2010. 8

  7. Magnitude of the Problem • Question: Why are these figures of such significant public health impact? • Answer: Each hereditary cancer comes from a family that could benefit immensely from genetic counseling. • DNA testing, surveillance, and highly-targeted management are the key!

  8. Genetic Counseling • Mandatory • Centers of Cancer Genetic Expertise • Physician Role, unfortunately, often insufficient

  9. Should we test all colorectal cancer for Lynch Syndrome? YES! Test everybody.

  10. Search for LS Among CRC Affecteds* Evidence: Among 500 CRC patients, 18 (3.6%) had LS. Of these 18:  18 (100%) had MSI-H CRCs;  17 (94%) were correctly predicted by IHC;  only 8 (44%) were dx < 50 years;  only 13 (72%) met the revised Bethesda guidelines; 1/35 cases of CRC show LS. *Hampel et al. J Clin Oncol 26:5783-5788, 2008.

  11. Molecular Genetic Screening for LS • Recommendation*: • All incident CRC and EC cases should be molecularly screened for LS. • MSI highly sensitive (89.3%). • IHC equally sensitive (91.2%), is inexpensive, is more readily available, and predicts the nonworking gene. • IHC is preferred method to screen for LS*. • *Hampel et al. J Clin Oncol 26:5783-5788, 2008.

  12. Cost-effectiveness of DNA Testing • Estimate the cost-effectiveness of genetic testing strategies to identify LS among newly dx CRC patients using MSI and IHC.* • Conclusion: • Preliminary tests seem cost-effective from the U.S. health care system perspective. • Detects nearly twice as many cases of LS as targeting younger patients. • MMR testing is not cost effective. • *Mvundura et al. Genet Med 12:93-104, 2010.

  13. Familial CRC Type “X” • Amsterdam Criteria positive but lacking MSI and MMR mutations will constitute ~ 40% of those AC-I without MMR mutations and therein referred to as familial CRC type X.* • 1) CRC > left side • 2)  CRC and extra colonic CRC • 3) Later age CRC onset • 4) Molecular genetics (MSI and IHC or MMR • mutation) ABSENT! • *Lindor et al. JAMA 293:1979-1985, 2005.

  14. Screening for Amsterdam Criteria LS* • a) Screening of all CRC patients meeting Amsterdam • Criteria (AC) would fail to detect half of all cases; • b) Screening those aged £ 50 would detect only • half of all cases; • c) Screening of all patients using Bethesda • Guidelines for MSI would fail to detect at least • 1/3 of all cases. • *Boland & Shike. Gastroenterology 138:2197.e1- • 2197.e7, 2010.

  15. Familial CRC • Familial clustering of CRC, like that for carcinoma of the breast and stomach, has been discussed for more than 100 years. • What does it mean from the standpoint of risk? • Best answer – First- degree relative of CRC affected has 2-3 fold excess risk for CRC compared to population expectations. • But is type X different? • Answer – Risk remains elusive!

  16. Mismatch Repair (MMR) Mutations Genetic Heterogeneity in HNPCC MSH6 MLH1 MSH2 PMS2 PMS1 Chr 7 Chr 3 Chr 2 HNPCC is associated with germline mutations in any one of at least five genes

  17. Cardinal Features of Lynch Syndrome • • Family pedigree shows autosomal dominant inheritance pattern • for syndrome cancers. • • Proximal (right-sided) CRC predilection: 70-85% of Lynch syndrome CRCs • are proximal to the splenic flexure. • • Earlier average age of CRC onset than in the general population: • - Lynch syndrome: 45 years; • - general population: 63 years. • • Accelerated carcinogenesis, i.e., shorter time for a tiny adenoma to develop • into a carcinoma: • - Lynch syndrome: 2-3 years; • - general population: 8-10 years. • High risk of additional CRCs: 25-30% of patients who have surgery for a LS-associated CRC will have a second primary CRC within 10 years, if surgery was < a subtotal colectomy.

  18. Increased risk for certain extracolonic malignancies • Endometrial • Ovary • Stomach • Small bowel • Pancreas • Liver and biliary tree • Muir-Torre cutaneous features • Brain, (glioblastoma) – Torre syndrome features • Prostate cancer • Breast • Possible Adrenal cortical carcinoma and others.

  19. Cardinal Features of Lynch Syndrome • • Differentiating pathology features of LS CRCs: • - more often poorly differentiated; • - excess of mucoid and signet-cell features; • - Crohn’s-like reaction; • - significant excess of infiltrating lymphocytes • within the tumor. • • Increased survival from CRC. • • Sine qua non for diagnosis is identification of germline mutation in MMR gene (most commonly MLH1, MSH2, MSH6) segregating in the family.

  20. COLONOSCOPY • Initiate age 20 – 25 • every other year to age 40; annually thereafter • must get good cleanout and visualize cecum • CRC – need subtotal colectomy

  21. EC Screening • Effectiveness of screening for EC is unproven; • Consequently, prophylactic surgery is the best option for ♀ who have completed their families.* • *Manchanda et al. Curr Opin Obstet Gynecol • 21:31-38, 2009.

  22. Screening for EC in LS* • No screening tool has been validated. • Ultrasonography (US) used to screen for atypical hyperplasia and cancer. • Considered normal if no polyps or intrauterine abnormalities seen and if maximum endometrial thickness < 4mm in postmenopausal ♀ on hormonal replacement therapy or < 6mm in other ♀. • *Lécuru et al. Int J Gynecol Cancer 20:583-587, 2010.

  23. N Engl J Med 354: 261-269, 2006.

  24. Could this be hereditary Colon Cancer

  25. Targeted CRC Screening • Screening is melded to LS’s natural history: • Proximal location colonoscopy • Early age of onset beginning at age 25 • Accelerated carcinogenesis every 1-2 yrs < age 40,then annually • Pattern of extracolonic cancers  targeted screening

  26. Dis Colon Rectum 53:77-82, 2010.

  27. Extended Colectomy* • Continued: • Times to subsequent CRC and subsequent abdominal surgery were significantly shorter in the control group (P < .006 and P < .04, respectively). • No significant difference in survival time between the cases and controls. • Conclusion: Even though no survival benefit the increased incidence of metachronous CRC and increased abdominal surgeries among controls warrant subtotal colectomy in patients with LS. • *Dis Colon Rectum 53:77-82, 2010.

  28. Cancer Control 16:14-22,2009.

  29. Meyer et al. Cancer Control 16:14-22,2009.

  30. J Clin Pathol 62:679-684, 2009.

  31. J Clin Pathol 62:679-684, 2009.

  32. J Clin Pathol 62:679-684, 2009.

  33. Familial Hereditary AC-1 without MMR (Familial CRC of syndrome “X”) Lynch Syndrome TACSTD1 (EPCAM) Sporadic FAP; AFAP Mixed Polyposis Syndrome Ashkenazi I1307K CHEK2 (HBCC) MUTYH (MAP) TGFBR1 PJSFJP CD BRRS = as yet undiscovered hereditary cancer variants Hamartomatous Polyposis Syndromes

  34. Hereditary Polyposis Syndromes

  35. Attenuated FAP • Later onset (CRC ~age 50) • Few colonic adenomas • Not associated with CHRPE • UGI lesions • Associated with mutations at extreme 5’, 3' ends of APC gene, & exon 9A

  36. Molecular Diagnosis of LS: Toward a Consensus • If tumor is MSI-positive, IHC is then done to direct mutational testing to a specific MMR gene, which MSI alone cannot do.* • If tumor is MSS, must weigh low probability of an informative IHC test and cost of performing it.** • *Engel et al. Int J Cancer 118:115-122, 2006. • **Lynch et al. J Natl Cancer Inst 99:261-263, 2007.

  37. BRAF V600E mutation and LS • BRAF V600E mutation can sort this out since when detected it excludes LS and contributes to improved cost-effectiveness of genetic testing for LS. • *Clin Gastroenterol Hepatol 6:206-214, 2008.

  38. MORPHOLOGY SUSPICIOUS FOR MSI-H Run PCR test for MSI status Is there MSI-H? FAMILIAL CRC TYPE “X” NO EVIDENCE OF LYNCH SYNDROME NO NO YES Is there loss of staining with any of the Abs? PUTATIVE LYNCH SYNDROME Run mutation analysis for BRAF V600E YES Is there BRAF V600E mutation? NO MMR GENES MUTATION ANALYSIS IHC for MLH1, MSH2, MSH6, PMS2 YES Is there a mutation in MMR gene? SPORADIC CRC WITH MSI-H NO YES LYNCH SYNDROME Gatalica Z, Torlakovic E. Fam Cancer 2008;7:15-26

  39. Frequency of MMR Mutations* • ~60% of Amsterdam+ families with clinically defined LS phenotype carry point mutations or large genomic deletions in the transcription of either MLH1 or MSH2 genes. • Conversely, the pathogenic change inactivating the MMR system is not known or not fully understood in the remaining ~40%. • *Lagerstedt-Robinson et al. J Natl Cancer Inst • 99:291-299, 2007.

  40. Frequency of MMR Mutations* • A portion of this ~40% lacking MMR mutations is caused by a mutation mechanism in the gene known as EPCAM. • Others have been classified as familial colorectal cancer Type “X”.** • *Kovacs et al. Hum Mutat 30:197-203, 2009. • **Lindor et al. JAMA 293:1979-1985, 2005.

  41. Diagnosis Genetic Counseling Phenotype site specific CRC Pathogenesis Pharmacogenetics Impacts Epithelial Cell Adhesion Molecule (EPCAM) Gene and Its Lynch Syndrome Connection

  42. 5’ EPCAM deletion Exons 8 and 9 and polyadenylationsequence Polyadenylation Sequence Transcriptional read through Hypermethylation of the MSH2 promoter Ligtenberg MJ, Nature Genetics 2009.

  43. Why LS with Site-Specific CRC? • Deletion in EPCAM results in hypermethylation and incomplete silencing of MSH2. • EPCAM mutation carriers may have phenotypic features that differ from carriers of MSH2 mutations – namely, an almost exclusive expression of site-specific CRC, thereby lacking extracolonic cancers.

  44. American and Dutch families have the same deletion in the EPCAM gene MSH2 EPCAM Deletion c.859-1462_*1999del (4.9 kb, starting in intron 7 and including exons 8 & 9) Lightenberg, Nature Genetics 2009.

More Related