Fundamentals of tumours

Question 1

Compare and contrast benign and malignant tumours (macroscopic and microscopic)

Answer 1

Benign
• slower growing
• well circumscribed
• often encapsulated by a layer of compressed fibrous tissue
• not locally invasive (although the tumour may push and compress the adjacent normal tissue as it increases in size)
• no metastatic potential
• tumour cells very closely resemble cell of origin ie. very well differentiated
• cells are uniform throughout the tumour
• few mitoses
• tumour cells have a normal nuclear:cytoplasmic ratio

Malignant (‘cancer’)
• faster growing
• poorly circumscribed
• non-encapsulated
• INVASIVE GROWTH with destruction of adjacent normal tissue
• METASTATIC POTENTIAL
• may or may not closely resemble cell of origin ie. variable differentiation
• cells and nuclei vary in shape and size (pleomorphism)
• many mitoses
• high nuclear:cytoplasmic ratio.
• nuclear staining (hyperchromatism)

Question 2

Define tumour grade and stage

Answer 2

Grading

• the grade reflects how closely it resembles (down the microscope) the normal tissue from which it is believed to have arisen ie. it is an assessment of differentiation:
• well differentiated: the cancer cells closely resemble the normal tissue.
• poorly differentiated: the cancer cells poorly resemble the normal tissue.
• correlates with aggressiveness of behaviour

Staging

• staging is the process of determining how much cancer there is the body and where it is located ie. it provides a quantitative assessment of the extent of anatomical spread by tumour
• TNM

Question 3

Define dysplasia- hint: broad definition, classification and basement membrane

Answer 3

Dysplasia may be defined as ‘disordered growth or differentiation’.

Dysplasia is characterised microscopically by varying degrees of decreased differentiation, more mitoses, high nuclear:cytoplasmic ratio, cellular/nuclear pleomorphism.

the cells have not yet invaded through the basement membrane.

Question 4

Explain why it is preferable to treat a patient with precancer rather than cancer

Answer 4

removing a precancerous lesion with a clear margin around it should be curative.

Question 5

What is lined by each type of epithelium?

• squamous epithelium
• glandular epithelium
• urothelium/ transitional epithelium

Answer 5

• squamous epithelium eg. skin and oesophagus, anus
• glandular epithelium eg. respiratory and gastrointestinal tracts.
• urothelium (old term - transitional epithelium) eg. urinary tract.

Question 6

Explain how tumour grade and stage differ from one another

Answer 6

Stage: extent of anatomical spread. Grade: aggressiveness of behaviour.

Question 7

Give examples of grading and staging systems used in clinical practice (3)- hint gynae cancers, lymphoma, CRC

Answer 7

• FIGO system is used for gynaecological cancers.
• Ann Arbor system is used for lymphomas.
• Dukes’ system is oden used for colorectal carcinoma (in addition to TNM staging).

Question 8

Explain the concept of premalignancy (precancer).

Answer 8

Precancer does not show invasive growth and does not have the ability to metastasise

Dysplasia/ carcinoma in situ

Question 9

4 reasons we stage cancer

Answer 9

• stage is usually the single most important prognostic factor for a cancer.
[Prognostic factors are factors which help predict the probable course and outcome of a disease].
• knowing the stage helps in planning the most appropriate treatment.
• staging provides a common language with which doctors can communicate about a patient.
• knowing the stage is important in identifying clinical trials that may be suitable for a particular patient

Question 10

Give examples of the different terminology used for premalignancy in different anatomical sites

Answer 10

Cervix- Cervical Intraepithelial Neoplasia
Endometrium- Atypical Hyperplasia
Bladder- Carcinoma In Situ
Prostate- Prostatic Intraepithelial Neoplasia
Colorectum- Low and High Grade Dysplasia
Breast- Ductal Carcinoma In Situ
Skin- Actinic Keratosis

Question 11

Outline the rationale for the breast, cervical and bowel cancer screening programmes

Answer 11

One of the main aims of the national breast, colon and cervical screening programmes is to detect and treat precancer.

Question 12

5 common sites for metastasis

Answer 12

Lung
Liver
Brain
Bone marrow
Bone

Question 13

5 effects of cancer metastasis at the common sites

Answer 13

Lung: Haemoptysis, pneumonia, pleural effusion
Liver: Jaundice, hepatic failure
Brain: Seizures, stroke
Bone marrow: Anaemia, leukopaenia, thrombocytopaenia
Bone: Pain, fracture, spinal cord compression

Question 14

Define paraneoplastic syndrome

Answer 14

a syndrome (ie. a collection of symptoms and signs) caused by substances produced by the tumour cells which act remotely from the tumour or its metastases.

Question 15

2 causes of paraneoplastic syndrome

Answer 15

• it may be caused by hormones, cytokines or other factors produced by the tumour cells.
• it may be caused by antibodies produced by the body to ‘fight’ the tumour but which unfortunately cross-react with normal tissues and damage them.

Question 16

2 examples of paraneoplastic syndrome

Answer 16

Cushing’s syndrome

Nephrotic syndrome

Question 17

How is dysplasia characterised?

Answer 17

Dysplasia is classified (‘graded’) according to the severity of changes seen on histology:
• in some anatomical sites (eg. cervix) three grades are used: mild, moderate, severe.
• in other anatomical sites (eg. colon) two grades are used: low and high.