Diagnosis and staging

Why do we need to stage tumours

• to see how far a tumour has grown

  • staging

• universal systems to estimate size of tumour

• evaluate metastasis presence

Why do we need to stage cancer

• gives information on prognosis

  • results and info predict how well a patient will do under treatment options

• permits baseline against which response treatment can be assesed

  • evaluate if treatment is working or not

• influences the choice of treatment

  • determine optimal treatment

What are the common elements of a staging system

• location of primary tumour

• tumour size + number

• lymph node involvement

• cell type and tumour grade

• presence or absence of metastasis

What does in situ mean

• early cancer that is present only in the layer of cells in which it began

  • basement membrane

what does localised mean

• cancer that is limited to the organ in which it began

  • without evidence of spread

What does regional mean

• cancer that has spread beyond the original site to nearby lymph nodes or organs and tissues

What does distant mean

• cancer that has spread from primary site to distant organs or distant lymph nodes

What does unknown mean

• cases for which there is not enough information to indicate a stage

What does the ‘T’ (tumour) in TNM staging mean

• T → primary tumour, size and invasiveness

• TX → primary tumour cannot be assessed

• TO → no evidence of primary tumour

• TIS → carcinoma in situ

• T_1-4 → increasing size & or local extent of primary tumour / penetration

What does the ‘N’ (Node) in TNM mean

• N → lymph node

• NX → regional lymph nodes can’t be assessed

• NO → no regional lymph node metastasis

• N_1-3 → regional lymph node metastasis

What does the ‘M’ (metastatis) in TNM mean

• M → distant metastasis

• MX → presence of distant metastasis cannot be assessed

• Mo → no distant metastatis

• M₁ → distant metastasis

What is stage 1 of ovarian tumours

• stage 1A

  • cancer in 1 ovary

• stage 1B

  • cancer in both ovaries

• stage 1C

  • cancer in the ovary and on the surface of one ovary

What is stage 2 of ovarian tumours

• stage 2B

  • cancer has spread to bowel or bladder

• stage 2C

  • cancer cells also in the fluid of abdomen

What is stage 3 of ovarian tumours

• stage 3A

  • cancer cells are in the lining of the abdomen under microscope

• Stage 3B

  • tumours of 2cm or smaller are in the lining of the abdomen

• Stage 3C

  • cancer is in lymph nodes

What is grading

• the extent to which the cancer cells are similar in appearance to the healthy cells of the same tissue type

• describe differentiation

• graded between 1-4

• grade 1 → well differentiation

• grade 4 → poorly differentiated

What does a grade 1 tumour mean

• less aggressive that grade 4

• affects choice of treatment modality or regime

What is clinical staging

• determines how much cancer there is

  • based on physical examination, imaging tests, biopsies

What is pathological staging

• can only be done on patients who have had surgery to remove or explore the extent of cancer

• combines results of both clinical staging and surgery results

What is restaging

• determines the extent of the disease if a cancer comes back after treatment

• determine best treatment option

What is the purpose of a clinical examination

• patient history

  • symptom description

What is the purpose of a physical examination

• provide clues as to the extent of cancer

• may determine the location and size of tumour

What is a laboratory test

• studies blood, urine, other fluids and tissues removed from body

What can pathologists look at using laboratory tests

• tumour size & appearance

• tissue of origin

• benign / malignant

• tumour differentiation

• primary tumour vs metastatic disease

• degree of local invasion

What are tumour markers

• substances ( proteins, biochemicals, enyzmes) produced by tumour cells

• released into blood

• produced by neoplastic tissue or human body in response to presence of cancer

How are tumour markers used

• used in conjunction with other tests

• diagnose, monitor treatment response and tumour recurrence

• variety of tumour markers

  • lower at early stags

  • higher in advanced disease

Name 2 examples of tumour markers

• prostate cancer

• prostate specific antigen

  • PSA

What is a PSA test

• measures the amount of PSA molecules in a patients blood

• normal for all men to have some PSA in their blood

• raised PSA → prostate cancer

What can cause raised PSA levels besides cancer

• UTI

• vigorous exercise

• prostate stimulation

• prostate problems

What are MRI scans

• do not use ionising radiation

• for soft tissue definition

• reconstructed in any plane

What is the technique of bone scans

• preparation → none

• injection of Tc-99m 20-25 mCi IV

  • hydration and frequent voiding

• wait 3hrs before imaging → avoid contamination

• empty bladder prior to scan

• change cloth and remove things likely to artifact

How are x-rays produced

• from an x-ray tube

  • following the acceleration of electrons from a hot cathode by a voltage difference → 25 - 125 kV

• created through photoelectric absorption or bremsstrahlung effects

  • electrons from cathode directed at anode

What causes the fluorescence in x-rays

• x-rays excite chemical salts

  • emit light

What is penetration

• the travel of x-rays through substances impenetrable to light

• x-rays are absorbed to a greater or lesser degree

  • depends on tissue thickness

How are CT’s used for cancer diagnosis and staging

• identification of pathology and positive lymph nodes, loco-regional and distant spread of disease

• enhance identification of tumours and metastatic disease

How are CT’s used for pre-treatment imaging

• data from CT scans transferred directly to radiotherapy planning systems

  • electron density information computed and translated into dose distribution data

What are the components of a CT

• table

• gantry that houses and x-ray tube

• detectors with x-ray filters

• collimators between source and detectors

• computer for image reconstruction

What are the 3 generations of CT scanners

• First generation

  • single x-ray beam projected onto a single detector

• second generation

  • fan beam and several detectors

  • larger imaging area

• third generation

  • arched bank of detectors opposite X-ray tubes

  • rotate at same time through connection in gantry

  • x-ray tube and detectors rotate around patient

What is an MRI

• uses magnetic properties of hydrogen atoms to generate images

• have high contrast and allow optimal soft-tissue imaging

What is a functional MRI

• blood oxygen level dependent

  • blood flow in regions of brain imaged through changing metabolic activity

How does a functional MRI work

• brain is active → blood flow increases through capillaries

  • in order for oxygen and glucose to be deposited and metabolised by neurone

• magnetic difference between oxyhaemoglobin and deoxyhaemoglobin detected as changes in MR signals

What are the limitations of an MRI

• resource issues associated with availability of scanners

• suboptimal ability of MRI to image bone and high density structures and tissue

  • doesn't depend on electron density of tissue

• doesn’t provide accurate images of the external contour of a patient

What is a PET scan

• demonstrates information about the physiological activity of tissues and organs at a molecular level

What happens during a PET scan

• IV injection of radioactive isotope

• positrons emitted from radioactive isotopes

• in vivo ditribution of x-rays or gamma rays received by external detectors