my presentation on colorectal carcinoma

1. COLORECTAL CARCINOMA
Pathogenesis & prognosis
SPEAKER: Dr. MANIK MANDAL (PGT)
MODERATOR :DR JAYATI CHAKRABORTY
(Professor and HOD)
Department of pathology
ESIPGIMSR

2. INTRODUCTION
Colorectal carcinoma(CRC) is the carcinoma
affecting caecum, colon and rectum.
Fourth most common carcinoma in male and 3rd
most common in female.
CRC constitute 10% of all cancer related death.
Peak incidence: 60-79 yrs.
Lowest incidence in India and Africa.

3. Anatomical location of CRC
Caecum-------------14 %
Ascending colon---10 %
Transverse colon---12 %
Descending colon---7 %
Sigmoid colon------25 %
Rectosigmoid junct.-9 %
Rectum--------------23 %

4. Symptoms associated with CRC
Pain
Rectal bleeding
Change of bowel
habit
Feeling of mass
Weight loss

6. Risk factors for CRC
Age >50 years
Sedentary lifestyle, Diet, Obesity
Family History of CRC
Inflammatory Bowel Disease (UC>CD)
Adenomas/ Polyps
Hereditary Syndromes -- familial adenomatous
polyposis (FAP), HNPCC,Turcot’s syndrome,
Gardener’s syndrome etc.

7. Factors implicated in
colorectal carcinogenesis
Increased risk
Consumption of red meat
Animal and saturated fat
Refined carbohydrates
smoking
alcohol

8. MODIFIABLE FACTORS
Alcohol consumption
1.Increase mucosal proliferation
2. Increase tissue nitrosamine
level
3. Activation of liver
procarcinogen
smoking
Tobacco contain polycyclic
aromatic hydrocarbons(PAH),
heterocyclic aromatic
amines(HAA), N- nitrosamine
Causes DNA damage in colonic
epithelium
Obesity
Adipokines like leptin and
adiponectins secretate from
adipocyte which slowly
changes the colonic
epithelium.
Consumption of red meat
Increased 2ndary bile acids
creat chaos within colonic
epithelium causes membrane
perturbation and DNA
damage.

9. Factors implicated in
colorectal carcinogenesis
Decreased risk
dietary fiber
vegetables
fruits
antioxidant vitamins
calcium
folate & Vitamin B

10. WHO classification of CRC
 Epithelial tumors:Premalignant lesions
 Adenoma
 Tubular
 Villous
 Tubulovillous
 Dysplasia (intraepithelial neoplasia, low grade)
 Dysplasia (intraepithelial neoplasia, high grade)
 Serrated lesions
 Hyperplastic polyp
 Sessile serrated adenoma / polyp
 Traditional serrated adenoma
 Hamartomas
 Cowden associated polyp
 Juvenile polyp
 Peutz-Jeghers polyp

11. WHO classification of CRC
Carcinomas
 Adenocarcinoma
 Cribriform comedo type
adenocarcinoma
 Medullary carcinoma
 Micropapillary carcinoma
 Mucinous adenocarcinoma
 Serrated adenocarcinoma
 Signet ring cell carcinoma
 Adenosquamous carcinoma
 Spindle cell carcinoma
 Squamous cell carcinoma
 Undifferentiated carcinoma
Neuroendocrine neoplasms
Neuroendocrine tumor (NET)
NET G1 (carcinoid)
NET G2
Neuroendocrine carcinoma
(NEC)
Large cell NEC
Small cell NEC
Mixed adeno neuroendocrine
carcinoma
EC cell, serotonin producing
NET
L cell, Glucagon-like peptide
producing, and PP / PYY
producing NETs

12. PREMALIGNANT LESION
Adenoma- polypoid
structure, 3 types.
Tubular-<1cm.
Villous – leaf or
finger like.
Tubulo-villous-
mixed, 25% tubular
and 75% villous.

13. Dysplasia is common
in adenoma-
characterized by enlarged
hyperchromatic nuclei,
nuclear spindling
stratification.
Low grade dysplasia
High grade dysplasia-
intramucosal carcinoma

14. SERRATED LESIONS
Serrated
architecture of
the epithelium
3 types-
1. hyperplastic
polyp
2.sessile serrated
adenoma/polyp
3.Traditional
serrated
adenoma/polyp

15. Flat adenomas:
 Gross:flat or slightly
raised plaques.
 M/E:tubular adenoma
with dysplastic
epithelium limited to
luminal surface of crypt
associated with
underlying non
neoplastic epithelium

16. FAMILIAL ADENOMATUS POLYPOSIS
FAP SYNDROME: caused
by mutation of APC gene on
chromosome 5q.Classified
as
 Classic FAP-over 500
adenomas that carpet mucosal
surface. At least 100 polyps is
necessary for the diagnosis.
Most are tubular adenomas.
 Occur some 20yrs earlier than
ordinary CRC.
 Prevention: early detection and
prophylactic colectomy in at
risk patients.
 Attenuated FAP: fewer
polyps (<100 no) ,most of them
in proximal colon.

17. Gardner’s syndrome:
 intestinal polyps, multiple osteomas,epidermal
cysts, fibromatosis.
 Lesions show coexistence of somatic and germline
mutations of APC gene.
Turcot’s syndrome:
 Adenomatous polyps, CNS tumors (glioblastomas),
AR inheritance.
 Mutation of APC/mismatch repair gene.

18. HNPCC SYNDROME
AD inheritance.Due to mutation in mismatch repair
gene.
Characterized by colorectal Ca with(lynch2) or
without(lynch1)extraintestinal tumors.
It is multiple,commonly right sided , mucinous ,
poorly differentiated, associated with Crohn’s like
lymphoid infiltrate.
Errors in mismatch repair gene leads to expansion
or contraction of tandem repeat sequences leading
to microsatellite instability

19. Hamartomatous polyposis syn.
Peutz Jegher’s syn.-
 Epithelial mutation of LKB1
gene on chr.19p(acts as
tumor suppressor gene)
 Loss of this gene play a role
in extra-intestinal tumor
formation..

20.  Genetic abnormality in
stromal cells of colonic
polyp
 Mutation in
SMAD4/DPC4 seen in
some cases.
 Predisposes to cancer by
stromal driven epithelial
proliferation.
 This suggests an
alternative hamartoma-
adenoma-carcinoma
sequence.
Juvenile polyposis syndrome

22. Common pattern of colorectal neoplasia

23. ADENOCARCINAM

24. ADENOCARCINOMA
Usually well to
moderately differentiated
adenocarcinoma.
Consistently elicits
inflammatory and
desmoplastic reactions.
Tumor may be seen
invading all layers of
bowel extending into
pericolic fat, perineural
spaces and viens.

25. MUCINOUS ADENOCARCINOMA
Define by >50% tumor volume
composed by extra cellular
mucin.
Large glandular structure
with pool of extracellular
mucin.
Worst prognosis
Related to MSI-H

26. SIGNET CELL ADENOCARCINOMA
It is rare in colorectal
region.
Presence of >50% tumor
cells showing signet ring cell
feature.
Intra cytoplasmic mucin
vacuole- push the nucleus to
the periphery.
High grade tumor and worst
prognosis

27. MEDULLARY CARCINOMA
Rare variant.
Pushing border at the
tumor edge.
Sheets of malignant cells
with vesicular nuclei,
prominent nucleoli and
abundant eosinophilic
cytoplasm.
Infiltration by intra
epithelial lymphocytes
Favourable prognosis.

28. SMALL CELL NUROENDOCRINE
CARCINOMA
<1%,poor
prognosis,almost all
cases having lymph node
and liver metastasis
1/3 arise from typical
adenomas
May show areas of
squamous differentiation
IHC:express neuron
specific enolase,Leu-
7,synaptophysin,chromo
granin.

29. VERY RARE VARIENTS
Serrated adenocarcinoma
Cribriform comedo type adenocarcinoma
Micropapillary adenocarcinoma
Adenosquamous carcinoma
Spindle cell carcinoma
Undifferentiated carcinoma

30. HISTOLOGICAL GRADING OF
COLORECTAL ADENOCARCINOMA
Criterion Differentiatio
n category
Numerical
grade
Descriptive
grade
>95% with
gland
formation
Well-
differentiated
1 Low
50-95with
gland
formation
Moderately
differentiated
2 Low
>0-49% with
gland
formation
Poorly
differentiated
3 High
High level of
MSI
Variable Variable low

31. ADENOCARCINOMA
Most common
carcinoma of colorectal
region(90%)
a)Well differentiated (95% gland
formation)
b)Moderately differentiated (50-
95% gland formation)
c)Poorly differentiated (<50%
gland formation)

32. IMMUNOHISTOCHEMISTRY
Expresses mucin protein MUC1, and
MUC3.Mucinous carcinoma expresses
MUC2.
Invariably positive for cytokeratin.
CK20 (+ve) and CK7 (-ve).
Reactivity for CEA is a rule.
CDX-2 a homeobox gene-in
proliferation and differentiation of
intestinal epithelial cells.

33. Tumor associated glycoprotein(TAG-72)is
present in 100% of invasive colorectal Ca.
Tumor associated antigen-large external
antigen(LEA) identified in tumor tissue and
sera.
Villin a cytoskeletal protein higly sensitive in
well &moderately differentiated carcinoma.
↑ed expression of cathepsin B.
Calretinin in minority of cases(also in
mesothelioma) shows positivity.
IMMUNOHISTOCHEMISTRY

34. CRC CARCINOGENESIS
MULTISTEP PATHWAY BIG BANG THEORY
Potentially a sequence of clonal
expansions throughout tumor
development.
After the initial transformation, tumors
grow as a single expansion of a mix of
clones.
Selection favors some clones and kills
others.
Selection is unimportant (after initial
transformation)
Clones compete. Subclonal mutations are
the result of selection of de novo clones.
Clones do not compete. Subclonal
mutations appear early (right after
transition to advanced tumor)
Heterogeneity varies from region to
region.
Uniformly high intra-tumor
heterogeneity

36. APC: encodes a protein that promotes cell migration and
adhesion. Also regulates the level of β-catenin. Lost earliest in
adenomas.
K-ras: Most frequently activated oncogene in CA colon, play a
role in intracellular signal transduction. Loss of K-ras prevent
apoptosis and promote growth.
P53: Loss of p53 seen in 70-80% of cases. Loss of P53 and
LOH of 18q cause chromosomal deletion(DCC) make
chromosomal instability.
Loss of SMADS:lack of SMAD2 and SMAD4 increases GI
tumorogenesis by increasing TGF-β which normally cause cell
cycle inhibition.
Accumulation of these mutations lead to colorectal carcinomas.

37. MSI PATHWAY
1. Microsatellites are nucleotide repeat sequence form insertion or
deletion loops during DNA replication.
2. MMR correct insertion and deletion loops and keep the microsatellite
at germline length.

39. PROGNOSIS
Tumor stage
Tumor histological type
Tumor histological grade
Lymph – vascular –
perineural invasion
Tumor perforation
Margins+ve
circuferential
marginlocal
recurrence
Tumor deposit
Treatment effect
Total mesorectal excision and
surgical clearance reduce
recurrence 30% to 8% and 5yrs
survival increases 48% to 68%.
Histopathological features
suggestive of MSI
Intra tumor lymphocytic
infiltration marked tumor
edge, ≥3lymphocyte/HPF

40. TREATMENT EFFECT

41. Adverse features
of primary
tumour
Adverse
vessel
invasion
Favourable host
response
Adverse surgical
technique
Greater extent of
circumferential
involvement
Muscular
invasion
Intratumoral
inflammation
Short distance
between
resection margin
and tumor
Bowel obstruction Lymhatic
invasion
Peritumoral
inflammation
Incomplete
excision with
residual tumor
Poor
differentiation
Perineural
invasion
Desmoplasia
Infiltrative
pattern of
invasion/budding
Reactive lymph
node
Selected
molecular
characteristics

43. TUMOR INVASION (T)

44. NODAL INVOLVEMENT (N)
At least 12 lymph node is
necessary.
Micrometastasis
measure>0.2mm but <2mm,
marked as N1(mic) and
M1(mic)

45. Molecular Genetic Testing
Type of test Test based Result observation
Bethesda panel protein
for MSI(BAT25, BAT26,
D2S123, D5S346 and
D17S250)
PCR 55-84% 1. +ve for 15% CRC
2.More favourable
MMR proteins (MLH1,
PMS2, MSH2 and MSH6)
IHC >90% 1. +ve for 15% CRC
2.More favourable
K-RAS testing PCR &DNA
sequencing
>95% 1. Lynch syndrome
associated CRC
2.Recommended for anti
EGFR therapy
BRAF testing PCR >90% 1.Sporadic CRC
2.BRAF wild type MSI-H
tumor best prognosis.
3.BRAF mutated MSS
worst prognosis.

46. Immunohistochemical staining for MMR
proteins
MLH1 MSH2 MSH6 PMS2 INTERPRETATION
+ve +ve +ve +ve Intact MMR
-ve +ve +ve -ve MLH1 germline mutation
+ve -ve -ve +ve MSH2 germline mutation
+ve +ve -ve +ve MSH6 germline mutation
+ve +ve +ve -ve PMS2 germline mutation

47. MLH1 -ve PMS2 -ve
MSH2 +ve
MSH6 +ve

48. NEW DEVELOPMENT
18q/DCC  increases disease severity.
K-RAS mutation result poor prognosis
THYMIDYLATE SYNTHASE 5FU
P27 cell cycle inhibitor
BCL-2  loss of it increases relapse
P53 loss of it causes tumor proliferation
EGFR- CETUXIMAB prevent invasion and
metastasis.
VEGF-BEVACIZUMAB  prevent angiogenesis.

49. CONCLUSION
Colorectal adenocarcinoma is a heterogeneous
disease that involves multiple tumorigenic pathways.
 Pathologic analysis provides histologic and
molecular information critical to appropriate patient
treatment, prognosis assessment, and family
counseling.
 The molecular mechanisms in tumorogenesis will
certainly lead to the development of new targeted
therapies and new molecular tests, which will
ultimately benefit the patients and their families.