Ovarian Cancer, from Molecular Pathology to the 2014 WHO Classification: What You Need to Know

Valencia, Venezuela 2016

Anaís Malpica, M.D.Professor

Department of Pathology

Contemporary Approach to Ovarian Cancer

• Ovarian cancer is a heterogeneous disease

• Each histotype represents a different disease

• No universal grading can be applied

Distribution of Ovarian Cancer Histotypes by Stage

Köbel M, et al.Int J Gynecol Pathol 2010

• The low grade serous carcinoma was characterized by:– Having a uniform, “boring”

appearance– Protracted clinical course

– Periodically he was running into additional specimens from these cases

– Patients were not dead in spite of large tumor volume

Low Grade Serous Carcinoma Emerged from Empirical Observations

Dr. Elvio G. Silva created these terms in the early 80’s when he realized that there were two types of serous carcinoma

Serous Carcinoma

Binary System (MD Anderson system)

• User friendly• Reproducible• Two different groups with differences:

– Molecular level– Pathogenesis– Histology– Immunohistochemistry– Clinical level

Low Grade Serous Carcinoma

• Definition

– A serous carcinoma characterized by the presence of uniform cells with mild to moderate cytologic atypia and usually a low mitotic index (≤ 12 mitoses per 10 high power fields)

High Grade Serous Carcinoma

• Definition

– A serous carcinoma characterized by the presence of pleomorphic cells with marked nuclear atypia (≥3:1 variation in size and shape), and a high mitotic index (>12 mitoses per 10 high power fields)

The MD Anderson Binary System for Grading Ovarian Serous Carcinoma

• Grade represents an independent prognostic factor on multivariate analysis

• Good correlation with FIGO and Shimizu-Silverberg grading systems

• Based on defined criteria– User friendly

• It involves only two diagnostic categories– It should provide better reproducibility

Low vs. High Grade Serous Carcinoma, Reproducibility

• Nine pathologists from academic centers and private pathology laboratories

• Overall Kappa statistics: 0.909• Interobserver Kappa:• 1st round: 0.717 to 1.000• 2nd round: 0.701 to 1.000• Intraobserver Kappa:• 8 pathologists: 0.775 to 1.000

(excellent)• 1 pathologist: 0.725 (good)

Low vs. High Grade Serous Carcinoma, Pathology Issues

• Cases with cytologic features difficult to assess– Perhaps more than moderate atypia, but not sure

about severe atypia– Check mitotic index– Immunohistochemical studies

• Ki-67, p16 and p53• Tumor heterogeneity

– Very rare, be careful with core biopsies • Pathologist does not follow diagnostic criteria

• Cases with cytologic features difficult to assess– Perhaps more than moderate atypia, but not

sure about severe atypia– Check mitotic index– Immunohistochemical studies

• Ki-67, p16 and p53

Low vs. High Grade Serous Carcinoma, Pathology Issues

Ascitic Fluid

Serous LMP with a Cribriform Pattern and Atypia

Area of Invasion with Marked Atypia and no Mitosis

Ki-67

p53 p16p53

Diagnosis

Low grade serous carcinoma associated with a serous tumor of LMP (borderline serous tumor) with a cribriform pattern

Low vs. High Grade Serous Carcinoma

Tumor Heterogeneity

• Rare cases

• To be careful with the presence of numerous mitoses or the presence of difficult to assess cytologic atypia in core biopsies

Low grade appearing areas

High grade carcinoma

Pathologist does not follow diagnostic criteria

High Grade Serous Ca Low Grade Serous Ca

Low vs. High Grade Ovarian Serous Carcinoma- Histologic Appearance

Differences in :• Incidence• Pathogenesis• Molecular Aspects• Immunohistochemical Features• Clinical Features• Genetic Risk

Low Grade

High Grade

Ovarian High Grade vs. Low Grade Serous Carcinoma, Incidence

– High grade serous carcinoma is the most common type of ovarian carcinoma

– Low grade serous carcinoma • A rare tumor accounting for less than 10% of

ovarian carcinomas• Recent review at MDACC (The American Journal

of Surgical Pathology 2015)– 4.7% of cases (22/471 ovarian carcinoma cases with

primary surgery at MDACC, 1995-2005)

Ekene Okoye, M.D.

Ovarian Low Grade Serous Carcinoma, Association with Serous Tumor of Low Malignant Potential

• Association with Ovarian Serous Tumor of Low Malignant Potential

– 60% of cases of low grade serous carcinoma

Malpica A, et al. 2004

• In a series of 276 cases of ovarian serous tumor of low malignant potential and long term follow up (≥ 5 years)

– 6.8% of the cases progressed to low grade serous carcinoma

• Interval: 7 to 288 months (58% ≥ 60 months)

Longacre T, et al. 2005

Deavers MT, et al. 2002

99 cases of advanced stage ovarian serous tumor of low malignant potential and long term follow up

18 cases Serous LMP with MP/CP

81 classicSerous LMP

cases

14 (78%) cases with progression or

recurrence

25 (31%) cases with progression or

recurrence

11 (79%) cases with low grade

serous carcinoma

17 (68%) cases with low grade serous

carcinoma

Ovarian High Grade Serous Carcinoma, Association with Serous Tumor of Low Malignant Potential

Malpica A, et al. 20041/50 (2%) case of ovarian high grade serous carcinoma was associated with a serous LMP

Low vs. High Grade Serous Carcinoma Differences in Pathogenesis: Molecular Evidence

Ovarian Tumorigenesis Model• Type I, tumors that arise in a stepwise manner from borderline (low malignant potential) tumors» Low grade serous carcinoma, prototypic type I tumor» BRAF and KRAS mutations

• Type II (certain cases originate from the fallopian tube fimbrial end)» High grade serous carcinoma, prototypic type II tumor» p53 mutation

Singer G, et al. 2002

Low vs. High Grade Serous Carcinoma Differences in Pathogenesis: Molecular Evidence

– MDACC experience (Wong KK, et al. Am J Path 2010)• Low grade serous carcinoma, KRAS

mutation• High grade serous carcinoma, p53

mutation

Current Proposals to Explain the Origin of High Grade Serous Carcinoma

• The fallopian tube = site of origin of ovarian carcinoma• Proposed > 50 years

ago in an effort to explain the presence of serous tumors in the ovary

• More recently, Dr. Crum and his group have worked extensively to support this theory

Current Proposals to Explain the Origin of High Grade Serous Carcinoma

• Multicentricity• Stimulus (most likely hormonal) acts over

uncommited mesenchymal stem cells and give origin to epithelial structures that eventually will turn into a neoplasm

• Animal studies with guinea pigs (Silva EG, et al 1998)

• P53 immunoreactivity is not sufficiently specific or sensitive to predict p53 mutations

• Low grade serous carcinoma– Up to 8% can show p53 mutation

• High grade serous carcinoma– Some cases lack aberrant expression of p53 by IHC

(8%)• Wild type p53 expression has been linked to worse outcome

– Approximately 97 % of cases show p53 mutation– Some cases that show no mutation arise inthe background of low grade serous carcinoma

Singer G, et al. 2005

Ahmed AA, et al. 2010Mc Alpine JN, et al. 2012

P53 and Serous Carcinoma

Two distinct patterns of p53 expression

LG HG

High Grade Serous Carcinoma

EGFR, p53, bcl-2, and c-Kit

Low Grade Serous Carcinoma

Hormone receptors e-cadherin

Low vs. High Grade Serous CarcinomaImmunohistochemical Differences

Brustmann H, 2008; O’Neill CJ, et al. 2005

Wong KK, et al. 2007

Low Grade vs. High Grade Ovarian Serous Carcinoma : Genetic Risk

• BRCA1/2 mutations have been found in cases of ovarian high grade serous carcinoma

• A rare case of ovarian low grade serous carcinoma has been reported to have BRCA1 mutation

Maurac I, et al. 2012

Kobel M, et al. 2008

Low vs. High Grade Serous Carcinoma: Differences in Biologic Behavior

– Patients with low grade serous carcinoma have a longer overall survival than patients with high grade serous carcinoma– Lesser response to conventional platinum

based therapy

– Patients with low grade serous carcinoma are younger and have a better survival than patients with high grade serous carcinoma

Gershenson DM, et al. 2006

Plaxe SC. 2008

• MEK inhibitors (GOG 0239)• BRAF inhibitors• mTOR/PI3K/AKT inhibitors• Anti-angiogenesis agents• IGF1R inhibitors

Targeted Agents

Endometrioid Carcinoma

Grade 1 : less than 5% of solid component

Grade 2 : 6 to 50% of solid component

Grade 3 : more than 50% of solid component

Endometrioid Carcinoma

• Survival of patients with grade 1 and 2 tumors is better that the one for patients with grade 3 tumors

Kline RC et al, 1990

Endometrioid Carcinoma

• Somatic mutations of the beta-catenin(CTNNB1) and PTEN genes are the most common genetic abnormalities in these tumors

• Compared with uterine endometrioid carcinomas, they show similar frequency of beta-catenin abnormalities but lower rate of microsatellite instability and PTEN alterations

Endometrioid Carcinoma

• Beta-catenin mutations (seen in 38% to 50% of the cases) are associated with:– squamous differentiation– low tumor grade– favorable outcome

Endometrioid Carcinoma

• Type of ovarian cancer with the most favorable prognosis– Lower grade– Lower stage– Responsiveness to chemotherapy

Clear Cell Carcinoma

Discrepancy between the degree of atypia and the mitotic index

Clear Cell Carcinoma

• 10% of ovarian cancers• Up to 50 % of cases associated with

endometriosis• Higher frequency of thromboembolic

complications and hypercalcemia (compared to HGSCa)

• Low-stage outcome better than stage matched HGSCa

• High-stage outcome worse than stage matched HGSCa

Clear Cell Carcinoma

• Approximately 50% of the cases carry AR1D1A mutations and lack BAF250 protein

• High rate of PIK3CA mutations• Low rate of p53 mutations• Low rate of KRAS, BRAF, PTEN mutations• Immunohistochemical Studies

– HNF1-beta is positive in more than 90% of the cases – Usually negative for WT-1, estrogen and

progesterone receptors – P53 wild pattern

Glypican 3 HNF-1β

Clear Cell Carcinoma Immunohistochemical Profile

Napsin-A

ER ER

p53 WT1

p16 PAX8

MLH1

Lynch Screening in the Ovary

• Clear cell carcinoma

• Endometrioid carcinoma

PMS2

MSH2MSH6

Microinvasive Mucinous Carcinoma

• Focus of invasion into the stroma < 5mm in greatest linear extent

• Marked cytologic atypia within the invasive focus

WHO 2014

Microinvasive Carcinoma

Microinvasive Mucinous Carcinoma

• Experience is limited• Rare cases have been reported with

recurrences cause of death

Nomura K, Aizawa S, Cancer 2000 Khunamornpong S. et al, Int J Gynecol Path 2011

WHO 2014

Mucinous Carcinoma

• Uncommon tumor • Accounts for less than 5% of the mucinous

neoplasms of the ovary• Frequently, metastatic mucinous

carcinomas to the ovary are diagnosed as an ovarian primary

Mucinous Carcinoma

• Most cases are stage I• Advanced stage cases have been

shown to have– a lower response rate to platinum-based

chemotherapy – a poorer prognosis

when compared with serous carcinoma

Mucinous Carcinoma

– Cases that grossly appear to be confined to the ovary tend to have negative lymph nodes• This finding suggests that routine

lymphadenectomy may be omitted in these patients

Schmeler K, et al. 2010

Mucinous Carcinoma

• Non-invasive (intraepithelial)

• Invasive

Non-invasive (Intraepithelial)Mucinous Carcinoma

• Behavior– Risk of recurrence for stage I cases:

5.8%

Invasive Mucinous Carcinoma

• Expansive or Confluent Type

• Confluent glandular growth measuring more than 5 mm (Hopkins) or more than 10 mm2 (WHO)

Invasive Mucinous Carcinoma

– Infiltrative Type • Small glands, cells

clusters or individual cells in the stroma measuring more than 5 mm (Hopkins) or more than 10 mm2 (WHO)

Ker20 Ker7 SATB2

Mucinous carcinoma of the ovary: keratin 7 +++, keratin 20 ++, PAX-8 +/-, CDX2 +, HR -

Metastatic colorectal adenocarcinoma to the ovary

Mucinous Carcinoma

– Invasive Carcinoma • 5 year survival = 91% for stage I cases

– Advanced stage disease cases, all die of disease (Riopel MA, et al. 1999)

• Infiltrative invasion appears to be more aggressive than the expansile type

(Lee KR, and Scully RE. 2000; Rodriguez IM, and Prat J. 2002)

Molecular Alterations inOvarian Mucinous Carcinoma

Molecular Alteration Ovarian Mucinous Carcinoma

MSI-H 22%

KRAS mutation 43%

BRAF mutation 0%

HER2 amplification 18%

APC or CTNNB1 mutations 9%

TP53 mutations 26%

Kelemen LE, Köbel M. 2011

Histotyping Pitfalls

• Endometrioid carcinoma with mucinous metaplasia is the tumor usually seen in the context of a seromucinous borderline tumor

• Seromucinous carcinoma arising in an endocervical type (seromucinous) borderline ovarian tumor is an extremely rare tumor

Endometrioid Carcinoma with Mucinous Metaplasia

Seromucinous CarcinomaArising in a Mucinous LMP,

Endocervical Type is an Extremely rare tumor

Transitional Cell Pattern

• It can be seen in serous or endometrioid carcinomas

• It was originally described as a pattern related to a better response to chemotherapy

• More recently associated with tumors detected in patient with BRCA mutations

FIGURE. Transitional cell carcinoma of the ovary is composed of multilayered papillae (A). High-grade cytologic features can be seen on higher power (B) as well as foci of necrosis. ER (C) and WT1 (D) immunostains are both positive.

FIGURE 1. Ribbon-like growth patterns simulating TCC, arising from cyst wall (A); showing fusion (B), interanastomoses (C), glandular architecture (D).

Malignant Brenner Tumor

Gertrude Goldschmidt(1912 –1994) also known as Gego