Colorectal Carcinoma Reporting in 2009

Transcription

1 Colorectal Carcinoma Reporting in 2009 Overview Colorectal carcinoma- new and confusing AJCC TNM issues Wendy L. Frankel, M.D. Vice-Chair and Director of AP Department of Pathology The Ohio State University Microsatellite instability (MSI) and Lynch Syndrome (LS) K-ras in metastatic colorectal carcinoma Colorectal Carcinoma 150,000 new cases in the US each year 9% of cancer deaths Treatment is usually resection Pathologic examination (gold standard) Stage and grade Helps guide post-op treatment Prognosis Predictive for chemotherapy response TNM Staging Developed by UICC (Europe) and AJCC (North America) Predictive of outcome Data driven / evidence based Updated frequently 7 th edition- out Nov 2009 CAP protocol (Washington K. et al) 3 elements T, N, M 1

2 Tumor Issues Grade- 50% glands cutoff Low; well and moderately differentiated High; poor and undifferentiated Serosal involvement- decreased survival T4a and b 4a; tumor penetrates visceral peritoneum 4b; tumor invades/adherent to other organs or structures (separate loop bowel, other) If uncertain- pick T3 rather than T4 Gunderson et al, J Clin Oncol, Serosal Involvement 4a- Serosa involved 4b- Invading kidney Node Issues- Tumor Deposits What Counts as a Lymph Node? Nodules without residual nodal tissue AJCC 5 th edition Size matters, 3mm AJCC 6 th edition Shape matters (contour) Round smooth Irregular AJCC 7 th edition Count all separately as N1c: lymph-vascular or discontinuous spread or lymph node? The Problem with Shape and What is a Lymph Node 2

3 Shape?? Discrete tumor deposit Discontinuous No residual lymph node identified Size or shape do not matter Does not change the T status even if only T1 or T2 Tumor Deposit N1c Positive Lymph Node The Problem with Residual Lymph Node Easy Harder 3

4 Lymph Nodes Number Pathologist and surgeon technique Patient age and treatment The more the better-? Minimum # Fat clearing (visual enhancement) does help some but not standard practice New N subdivisions- N1a (1), b (2-3), c (deposit), N2a (4-6), b (7) Goldstein N, Am J Surg Pathol, 2002; Cserni G, J Surg Oncol, 2002; Le Voyer TE, J Clin Oncol 2003; Chang GJ, JNCI, 2007; Dillman RO, Cancer, 2009 Other Changes in AJCC TNM 7 th Edition M divided into M1a and b Small and large vessel lymph-vascular invasion combined No more R (residual tumor) mentioned Can be assigned by clinician Tumor regression grade in carcinoma status post neo-adjuvant therapy Complete (0) to poor (3) TNM Stage Groupings Stage IIIA T1-T2 T1 N1 N2a Stage 0 Tis N0 Stage I T1 T2 N0 N0 Stage IIA T3 N0 Stage IIB T4a N0 Stage IIIB Stage IIIC T3-T4a T2-T3 T1-T2 T4a T3-T4a T4b N1 N2a N2b N2a N2b N1-N2 Stage IIC T4b N0 Stage IVA Any T Any N M1a Stage IVB Any T Any N M1b 4

5 Yosemite Vernal Falls Sept 1, 2009 New and Potentially Important Additions to CAP Checklist * Not required but elements may be clinically important Histologic features suggestive of MSI Ancillary studies MSI status Immunohistochemistry for mismatch repair proteins and B-raf K-ras MSI (Microsatellite Instability) 2-3% Lynch Sx Germline Mutation MMR genes MLH1 MSH2 MSH6 PMS2 Colorectal Cancer 15% 85% CIN (Chromosome Instability) 13% 1% 80+% Sporadic FAP Sporadic Epigenetic silencing of MLH1 by hypermethylation of its promoter region Most cancers occur in older people Germline Mutation APC Acquired APC, p53, DCC, K-ras, LOH,... Why is MSI Important? All MSI CRC patients have a better prognosis MSI CRC patients may need different treatment (do not respond as well to 5FU-based chemotherapy) LS patients at high risk for second primary cancers (CRC and others) LS patients have at-risk relatives who could benefit from genetic testing Ribic, NEJM 2003; Carethers, Gastroenterol 2004; Popat, J Clin Onc 2005; Lynch, Eur J Hum Genet 2006; Ward, J Pathol 2005; Jover, Gut 2006; Jover, Eur J Cancer 2008; Sargent, J Clin Onc 2008, ASCO. 5

6 Lynch Syndrome (HNPCC) Most common hereditary CRC syndrome 2-3% of CRCs Autosomal dominant, penetrance 80% Susceptibility to CRC & extracolonic cancers Germline mutation in genes belonging to DNA MMR family- MLH1, MSH2, MSH6, PMS2 Mutations in these genes lead to defective DNA repair and microsatellite instability Early but variable age at CRC diagnosis (~45 years) Tumor site in proximal colon predominates Extracolonic cancers: endometrium, ovary, stomach, urinary tract, small bowel, bile ducts, sebaceous skin tumors Clinical Features LS Colorectal Uterine Stomach Ovary Bladder Risk, male Risk, female ASCO Histology Microsatellite instability (MSI) Histology MSI CRC Intratumoral lymphocytic response (TIL)- most sensitive Peritumoral lymphocytic response (Crohn-like) Mucinous and signet ring cells Poorly differentiated, medullary carcinoma, tumor heterogeneity Sensitivity and specificity Jass J, Gut 1998; Jass J, Fam Cancer 2004; Alexander, Am J Pathol 2001; Yearsley M, Hum Pathol 2006; Greenson, Am J Surg Pathol, 2009 Mucinous Carcinoma Crohn-like Reaction 6

7 9/4/2009 Histology MSI CRC Typical Colon Cancer Intratumoral Lymphocytic Response (TIL) Tumor Heterogeneity MSI CRC Serrated Background Colorectal cancer CAP Checklist *Histologic features suggestive of MSI Intratumoral lymphocytic response (TIL) None, Mild to Moderate (2 per HPF), Marked (3) Peritumor lymphocytic response (Crohnlike) None, Mild to Moderate, Marked Tumor subtype and differentiation Suggests sporadic rather than germline mutation (Lynch syndrome) Mucinous (specify percentage) Medullary High histologic grade 7

8 Detection of MSI and LS Patients History (LS) Less useful; smaller families, polypectomy Amsterdam and Bethesda < 50% sensitive in unselected patients Histology (MSI and LS) Evaluate MMR system (MSI and LS) MSI- tumor DNA IHC- tumor protein CRC with MMR Deficiency Microsatellite instability testing Direct assessment on molecular level Requires DNA from tumor and normal Molecular laboratory IHC for the MMR proteins Assesses presence/absence of protein 100% tumors with abnormal IHC are MSI 95% MSI tumors have abnormal IHC Any Pathology Department Immunohistochemistry Methylation or Germline Mutation MLH1 Identify MMR proteins Normally present If protein is absent, gene is not being expressed (mutation or methylation) Helps direct gene testing by predicting likely involved gene If abnormal IHC (absent), MSI MLH1 MSH2 MLH2+ MLH1- MSH6+ PMS2- PMS2 MSH6 8

9 IHC - Problems in Interpretation Variability Weak nuclear staining Cytoplasmic staining Tissue and fixation? Columbus Area LS Study 1566 CRC; 19.6% MSI, 2.7% LS (44) 22/44 (50%) > 50yo; range 23 to 87 11/44 (25%) did not meet Amsterdam or Bethesda Of 35 families, 249 tested, 109 Lynch Large scale routine screening useful Screening by IHC similar efficacy as MSI genotyping Hampel, N Eng J Med, 2005; Hampel, J Clin Onc, 2008 Clinical Testing for Lynch Syndrome and MSI - Choices MSI and/or IHC ordered by clinician Based upon clinical and family history MSI and/or IHC ordered by pathologist too? Histology (± history) Call clinician or pathologist directed? Based on age and histology: If <60 y/o, MsPath score 1, sens 93%, spec 55% for MSI-H (Jenkins, Gastroenterol, 2007) Based on other (Greenson, AJSP, 2009) Routine testing on all CRC (IHC or MSI) Screening is Feasible for LS Choosing the Test MSI vs. IHC IHC is available in virtually all hospitals MSI requires molecular diagnostics and normal for comparison IHC with 4 antibodies is similar in cost to MSI with 5 markers IHC directs gene testing saving money Ethical issues surrounding IHC IHC and MSI have limitations 9

10 CRC dx >45 & No personal or family history Stop How to Follow-up on IHC Results All Present 80% CRC dx <45; OR FDR with CRC; OR Multiple primaries Refer to Clinical Cancer Genetics MLH1 & PMS2 Absent 15% B-raf CRC dx <60; OR Family or personal history of Lynch cancer - + CRC dx >60 & No personal or family history Stop MSH2& MSH6, or MSH6 or PMS2 Absent - 5% Refer to Clinical Cancer Genetics B-raf Mutation Analysis (MLH1, PMS2 absent) B-raf is a kinase encoding gene in ras/raf/mapk pathway Present in about 5 to 22% CRC DNA test on tumor (fresh, frozen or fixed) Exon 15 amplification with PCR Sequencing for point mutation V600E If mutated, abnormal MMR not due to LS Presumed sporadic methylation No need for additional workup (gene sequencing, methylation) MLH1 & PMS2 Absent MSH2 & MSH6 Absent 15% of the time CRC is MSI Better prognosis 80% acquired methylation of MLH1 20% will be LS Test B-raf MLH-1 MSH-6 MSH-2 PMS-2 3% of the time CRC is MSI Better prognosis Most likely LS due to either MSH2 or MSH6 gene mutation Always refer to Genetics MLH-1 MSH-6 MSH-2 PMS-2 10

11 9/4/2009 MSH6 Absent PMS2 Absent 1% of the time CRC is MSI Better prognosis Most likely LS due to an MSH6 gene mutation Always refer to Genetics MLH-1 MSH-6 MSH-2 1% of the time CRC is MSI Better prognosis Most likely LS due to an PMS2 gene mutation Always refer to Genetics PMS-2 Adenomas and LS MLH-1 MSH-6 MSH-2 PMS-2 Adenoma and Adenocarcinoma Lynch Syndrome Adenocarcinoma Adenoma If absent, directs genetic testing If present, not exclude LS Halvarsson, Mod Pathol 18,

12 Adenoma Adenoma and Adenocarcinoma Lynch Syndrome Adenocarcinoma Adenoma Adenocarcinoma MLH1/PMS2+ MSH2/MSH6+ MSH2/MSH6- Summary CRC: MSI / Lynch Syndrome The detection of MSI is important to identify LS and prognosis Identification based on history and pathology What s new MSI predictive marker (no response to 5FU based chemotherapy) Some centers using information for trx IHC or MSI similar detection MMR deficiency IHC or MSI evaluation more common Should at least mention suspicious histology Routine IHC or MSI some centers B-raf part of work-up algorithm Yosemite, Sept El Capitan Metastatic Colorectal Carcinoma Why Check for K-ras Mutation? 12

13 Metastatic Colorectal Carcinoma Survival has nearly doubled in the past decade Combinations of standard chemotherapy - 5 flurouracil, irinotecan, oxaliplatin New targeted therapy with monoclonal antibodies Inhibition biological pathway and molecules involved in tumor growth EGFR (Cetuximab, Panitumumab) VEGF Response rate is variable Increased cost and toxicity so need to select responders PREDICTIVE MARKERS (K-ras) Ras Proteins Family of proteins: H-Ras, K-Ras and N-Ras Links extracellular signals (ie growth factors) through membrane receptors to intracellular signals To activate pathways leading to cell growth and survival Ras Mutation Ras: Downstream Signaling Single amino acid change causes constant stimulation in the absence of growth factors Most commonly mutated codons 12, 13, 61 Locked in on state Since there is constitutive activation downstream of EGFR, anti-egfr treatment (Cetuximab) is not effective ON Cetuximab RTK= EGFR, VEGFR Sebolt-Leopold, J. S. Clin Cancer Res 2008;14:

14 Practical Issues K-ras Specimen FFPE, fresh, frozen Primary or metastatic Microdissection - not necessary Test DNA from tumor Exon 2 of Kras amplified by PCR Sequenced to evaluate point mutation Routine or by request Not first-line therapy all patients Summary K-ras and CRC Monoclonal antibodies against EGFR are active in metastatic CRC Patients whose tumors contain mutant K-ras do not benefit from cetuximab or panitumumab, either single agent or in combination with cytotoxic chemotherapy Metastatic CRC must be tested for K-ras mutation prior to treatment with monoclonal antibodies to EGFR K-ras analysis done by request Other gene mutational analysis will be neccessary in the future to predict response to therapy Colorectal Carcinoma CAP Checklist *Ancillary Studies Microsatellite instability (method) Immunohistochemistry for mismatch repair Intact or lost (do not use pos or neg) MLH1 MSH2 MSH6 PSM2 B-raf V600E mutational analysis (method) K-ras mutational analysis (method) Take Home Messages Updated AJCC TNM will include new elements MSI and Lynch What s old? We can ID them New? We do ID them, predictive trx 5FU K-ras What s old? K-ras in CRC, so what? New? Predictive trx Cetux (EGFRi) 14

15 QUESTIONS? Yosemite Sept 1, 2009 Immunohistochemical Stains MLH1 (1:40) and PMS2 (1:200), MSH6 (1:400) BD MSH2 Calbiochem (1:200) Antigen retrieval TRS ph 9.0 (6.0 for MSH2), pressure cooker (steamer OK) Biocare Medical s Mach 3 detection system Amsterdam Criteria- (3,2,1) Amsterdam 1 developed in 1991 (ICG- HNPCC) to standardize clinical criteria to identify HNPCC Amsterdam II (1998); HNPCC-associated cancers 3: HNPCC-associated cancers in 3 relatives plus 2: 2 successive generations affected 1: 1 relative CRC diagnosis < 50 yo 1 affected person is FDR of the other two 15

16 Bethesda Guidelines- revised 2004 To identify patients for MSI testing (1996) Amsterdam criteria or Individual with CRC dx <50 yo Synchronous or metachronous CRC, or other HNPCC-associated tumors regardless of age CRC with MSI-H histology dx <60 yo CRC with >1 FDR with an HNPCC-associated tumor, with one cancer dx <50 CRC with >2 FDRs or SDRs with an HNPCCassociated tumor, regardless of age International Workshop HNPCC Dec 2002, Bethesda, MD Umar A, et al. JNCI. 2004;96(4):