Topic 6-7: Histological Diagnosis and Molecular Pathology of Tumors

Question 1

6. Histological Diagnosis of Tumors

For the majority of solid tumors, what is the most important prognostic factor?

Answer 1

The stage of the tumor

Question 2

6. Histological Diagnosis of Tumors

Pathological examinations are classified at the time relative to surgery to remove tumors, so they are classified in these 3 ways:

Answer 2

pre-operative, intra-operative, and post-operative

Question 3

6. Histological Diagnosis of Tumors

What are the two types of cytological tests?

Answer 3

1. exfoliative cytology: cells shed from the surface of a body cavity (e.g. cervical screening, broncheoalveolar lavage)
2. fine needle aspiration: suck out some cells from a potential tumor mass, e.g. in thyroid, breast, lymph nodes. doesn’t preserve cell architecture like a biopsy does

Question 4

6. Histological Diagnosis of Tumors

What are some ways that tissue biopsy may be performed? (4 are listed)

Answer 4

• Endoscope
• Core needle
• Excision
• Abrasion

Question 5

6. Histological Diagnosis of Tumors

What is the most common type of intraoperative pathological examination?

What is an alternative that may also be performed?

Answer 5

• Frozen section (FS) analysis is most common

- However, imprint cytology (IS) can also be performed on cut lesions

Question 6

6. Histological Diagnosis of Tumors

What are the main 4 steps of tissue preparation for histological analysis?
(very simplified form that’s mentioned in the e-book)

Answer 6

1. fixation
2. making the sample permeable for paraffin
3. embedding the sample in paraffin
4. staining with haematoxylin-eosin

Question 7

6. Histological Diagnosis of Tumors

8 things are typically included in histological reports for solid tumors. To make it easier, here are the last 4:

• Perineural invasion
• Surgical margin status
• Lymph node status
• TNM classification and staging

What are the other 4?

Answer 7

• diagnosis
• tumor size
• histological grade
• vascular invasion

Question 8

6. Histological Diagnosis of Tumors

8 things are typically included in histological reports for solid tumors. To make it easier, here are the first 4:

• diagnosis
• tumor size
• histological grade
• vascular invasion

What are the other 4?

Answer 8

• Perineural invasion
• Surgical margin status
• Lymph node status
• TNM classification and staging

Question 9

6. Histological Diagnosis of Tumors

How is histological grade determined?

Answer 9

Based on the tumor cell’s similarity to the cell that it derived from, i.e. how differentiated the cell is

Question 10

6. Histological Diagnosis of Tumors

What are grades 1-3 with the Bloom-Richardson (breast cancer) scale?

Extra: what is this scale based on?

Answer 10

• Grade 1: well-differentiated
• Grade 2: moderately differentiated
• Grade 3: poorly differentiated

Based on tubule formation tendency, mitotic count, and nuclear pleomorphism

Question 11

6. Histological Diagnosis of Tumors

Which grading system is used for prostate cancer?

Answer 11

Gleason grading system

-defined by glandular architecture, while the cytological characteristics aren’t taken into account

Question 12

6. Histological Diagnosis of Tumors

What are the 3 different options for surgical margins / resection margins?

What is the importance of this?

Answer 12

• R0: no cancer cells seen microscopically at the resection margin
• R1: cancer cells at the resection margin only seen microscopically
• R2: cancer cells at the resection margin seen even macroscopically, without microscope

Important to predict local recurrence

Question 13

6. Histological Diagnosis of Tumors

Does vascular invasion refer to only blood vessel invasion, lymph node invasion, or both?

Answer 13

Both

Vascular invasion shows increased likelihood of recurrence + metastases

Question 14

6. Histological Diagnosis of Tumors

What is the basis of using histology to determine the effectiveness of neoadjuvant treatments?

Answer 14

Determining the ratio of viable/residual tumor compared to therapy-induced necrosis and/or inflammatory reaction to the tumor + metastases

Question 15

6. Histological Diagnosis of Tumors

What is tumor budding?

Answer 15

The presence of individual cells and small clusters of tumor cells at the “invasive front” of carcinomas. Represents epithelial-mesenchymal transformation (EMT)

Adverse prognostic factor, especially used for colon carcinoma.

Question 16

6. Histological Diagnosis of Tumors

What are tumor-infiltrating lymphocytes (TIL)?

Answer 16

T and B cells that have invaded the tumor tissue, typically associated with a better outcome as the immune system is hopefully targeting the tumor. Better outcomes in melanoma, ovarian cancer, etc.

May also indicate genetic status of the tumor (e.g. microsatellite instability in colon cancer, showing poor DNA mismatch repair as in Lynch syndrome)

Question 17

6. Histological Diagnosis of Tumors

What are 4 important factors used to determine the lymph node status?

How is lung cancer different from most other cancers when determining the lymph node status?

Answer 17

1. number of lymph nodes involved
2. localization of lymph nodes
3. size of the lymph node metastases
4. tumorous infiltration of the surrounding tissues

Lung cancer is unique in that only the location of the LN mtx matters

Question 18

6. Histological Diagnosis of Tumors

What is the international standard method used for tumor staging?

(reminder that this is the most important aspect for oncological histopathology)

Answer 18

TNM
T: Tumor size
N: lymph Node
M: (distant) Metastases

Specific aspects of TNM are unique for various types of cancer

Question 19

6. Histological Diagnosis of Tumors

What are the 3 types of histological reports?

Answer 19

1. descriptive (narrative)
2. standardized (synoptic, form-based)
3. structured (electronic, machine-readable XML)

Question 20

7. Molecular Pathology of Tumors

What are the 2 main purposes of molecular pathological (essentially genetic) analysis?

Answer 20

1. Determine prognosis: some mutations associated with worse prognosis than others
2. Determine targeted therapy: some drugs either will or won’t work if certain mutations are present

Question 21

7. Molecular Pathology of Tumors

To treat non-small cell lung cancer, which EGFR inhibitor can only be used if ALK or ROS1 translocations are present?

Answer 21

Crizotinib

Question 22

7. Molecular Pathology of Tumors

To treat non-small cell lung cancer, which gene cannot be mutated in order for EGFR tyrosine kinase inhibitors (e.g. Gefitinib, Erlotinib) to work?

Answer 22

RAS

Question 23

7. Molecular Pathology of Tumors

Which 4 genes are often tested for abnormalities in non-small cell lung cancer?

Answer 23

• EGFR (mutation): determines that it’s sensitive to EGFR TKIs (esp. common w/ adenocarcinoma in non-smoking women)
• RAS (mutation): determines that it’s resistant to EGFR TKIs. (most common adenocarcinoma mutation)

-ALK (translocation) and ROS1 (translocation): determine if sensitive to Crizotinib

Question 24

7. Molecular Pathology of Tumors

Which 3 genes are often tested for mutations in the case of colon adenocarcinoma?

What additional molecular examination is often done?

Answer 24

• KRAS: positivity = resistance to anti-EGFR drugs
• NRAS: positivity = resistance to anti-EGFR drugs
• BRAF: negative prognostic factor

+microsatellite instability often tested (assc with R side colon carcinoma, react better to immunotherapy)

Question 25

7. Molecular Pathology of Tumors What gene is often tested in the case of melanoma? Why?

Answer 25

BRAF - mutation means Vemurafenib-sensitive

Question 26

7. Molecular Pathology of Tumors What gene is most often tested in the case of breast carcinoma? Why? What are some other genes tested?

Answer 26

-most common: ERBB2 (aka HER-2) - amplification means sensitivity to Trastuzumab and Lapatinib Also reflex test: - Ki67 proliferation index (prognostic value) - Estrogen receptor (ER) and Progesterone receptor (PR) to see if hormone therapies can work

Question 27

7. Molecular Pathology of Tumors What are the ideal conditions to fix biopsy tissue in order to be able to perform DNA tests on it?

Answer 27

- fixation lasts only 24-48 hours - neutral pH (~7) - 10% formalin solution + 4% formaldehyde either over- or under-doing any of these steps can damage the DNA, making molecular processing impossibleq

Question 28

7. Molecular Pathology of Tumors What is the first step of molecular pathological examination?

Answer 28

histological examination of HE stains by an expert

Question 29

7. Molecular Pathology of Tumors What are the 3 major methods of molecular pathological diagnostics?

Answer 29

1. immunohistochemistry: detects proteins 2. in situ hybridization (ISH): detects longer DNA sequences, translocations, and amplifications 3. PCR methods: detect smaller abnormalities/mutations +/- next generation sequencing (NGS), simultaneously tests several genes from multiple patients

Question 30

7. Molecular Pathology of Tumors What is "reflex testing"?

Answer 30

Molecular tests are automatically performed after every histological examination in advanced-stage patients. Means patient-specific therapy may be started immediately

Question 31

7. Molecular Pathology of Tumors What novel anti-cancer immunotherapy drugs have been useful in treating lung adenocarcinomas and squamous cell carcinomas, even if they are RAS positive? What are 2 predictive markers used to predict the likely therapeutic value of these drugs?

Answer 31

Checkpoint inhibitors: PD1 antagonists, CTLA4 antagonists Predictive markers: PD-L1 protein expression, microsatellite instability

Question 32

7. Molecular Pathology of Tumors If immunohistochemistry doesn't effectively diagnose HER2 status of a breast cancer, what other method can be used?

Answer 32

FISH (fluorescence in situ hybridization)

Question 33

7. Molecular Pathology of Tumors What is "triple-negative" breast carcinoma? What other genetic analysis might be considered in this case?

Answer 33

- ER, PR, and HER2 negative | - consider BRCA1/BRCA2 analysis. BRCA positive -> sensitive to PARP inhibitors (new drugs.. e.g. olaparib)