Staging investigations Flashcards
What is the major way in which colon cancer is diagnosed?
Following a colonoscopy
How long do colonoscopy biopsies take to come back?
72 hours
Why is staging a critical process?
Tells the biology of the tumour and whether patients will respond to treatment
What are key radiology techniques involved in colon cancer?
CT
MRI
Characteristics of CT scan
Key for colorectal cancer
Take images of chest, abdomen and pelvis
Take images of chest, abdomen and pelvis
Good test - good resolution but high radiation
Amount of radiation coming down as technology advances
Characteristics of MRI
Used less often
Only for rectal tumour
Image in pelvis is better in MRI due to boney skeletal structure surrounding the rectum
What are the two systems to stage a tumour?
TNM - Tumour-Nodes-Metastasis
The Duke’s system
Why is staging important?
Guides the types of treatment employed for the patient
Tells how advanced the tumour is, how it spreads and the biology of the tumour
Tells if the tumour will respond to treatment at hand
What is the TNM staging system?
Adapted for specificities of various cancers
Determine
- How much the tumour has spread
- If infected the lymph nodes
- If spread to other organs
What are the different stages of TNM staging?
TX - Primary tumour cannot be assessed
T0 - No evidence of primary tumour
T1 - One layer, localised
T2 - Invade adjacent layers
T3 - Invaded up to the peritoneum
T4 - Invaded outside of the organ, beyond and distant
NX - Regional lymph nodes cannot be assessed
N0- No regional lymph nodes metastasis
N1 - Metastasis in 1-3 regional lymph nodes
N2 - Metastasis in 4 or more regional lymph nodes
MX - Distant metastasis cannot be assessed
M0 - No distant metastasis
M1 - Distant metastasis present
How is the TNM system important?
Determines treatment used
What is the Duke’s system?
Older
Usually also stated on staging reports
Staging in Duke’s system
Duke’s A - tumour in the epithelium
Duke’s B - tumour in the mucosa, submucosa and muscle
Duke’s C - tumour spread to the lymph nodes
Duke’s D - tumour spread far in the body. Invaded other organs.
Does biopsy indicate staging of cancer?
No information
Only tells us if it is cancer or not
What other investigations are needed to determine the stage of the cancer?
CT or PET scan
Tell about metastasis of nodes.
Sometimes nodes are indeterminate - approximation.
Fine detail of invasion of the layers by the cancer is normally approximated in radiology.
Once had idea and ruled out metastasis = surgery
Why is surgery necessary in colorectal abnormalities?
Needed regardless to improve symptoms
The cancer is resected out - sigmoid colectomy in sigmoid cancer
The lymph nodes in the mesentery are also taken
The samples taken out can be used to accurately determine the level of infiltration of the cancer into the mucosal walls as well as its invasion of the lymphoid system
What is the only accurate way of staging colorectal cancer?
Accurate staging only happens after surgery
Based on this we can determine treatment methods
What are the different radiological investigations that can be done during colorectal cancer treatments?
Staging CT
PET scans
Follow-up CT
MRI
Abdominal ultrasound and chest X-rays
What is a staging CT?
Chest, abdomen and pelvis
Imaged to assses the etent of the tumour within the abdomen and for the presence of distant metastases
What is a PET scan?
May be performed if the CT scan is ambiguous
What is a follow-up CT?
Of chest, abdomen and pelvis
Typically carried out after surgery and or chemotherapy
When is a MRI performed?
Specifically for rectal cancers
When are abdominal ultrasounds and chest x-rays performed?
Used as staging investigations
How are treatment options for a patient discussed?
At multidisciplinary team meeting
Working hub of how patients are managed
Bring prespectives together since so many disciplines are involved to decide treatment options
What are the 3 steps of deciding treatment options for colorectal cancer sufferers?
- Diagnosis with an endoscope
- CT - reviewed in meeting. together with histopathologies
- Decisions - need more information? How do the bits tie together?
What are ways to confirm the lymph nodes are positive for cancer?
Nodes are difficult to determine whether definitively positive for cancer using only size
PET scans
MRI - for rectal cancer
Members of MDT meetings
Specialist team made of surgeons, physicians, oncologists, histopathologists, radiologists, nurses
Represent patient’s wishes
How often do MDT meetings happen?
Meet once a week
Characteristics of MDTs
Specific MDTs for different conditions
Meet once a week to discuss newly referred patients with suspected or confirmed colorectal cancer
Plans a treatment programme specific to individual patient needs
Treatment options are discussed with patients or their family at a subsequent appointment
What are the advantages of MDTs?
Represent different opinions
Decisions are made in collegiate way
Things can be reviewed appropriately
Ensures mistakes are not made
Follow strict timeline
What is a colectomy?
Surgical resection of the affected colon
Curative treatment in colorectal cancer
Aims to excise
- the tumour with at least 5 cm clearance
- the entire mesentery
- the blood vessels supplying the tumour
What happens if the cancer is located in the anal canal?
Requires removal of the entire rectum and anus
A permanent colostomy opening is made in the abdomen
What is the margin for removal of the anal canal?
If the tumour allows for a 2 cm margin of clearance from the anal canal an anterior resection is possible
This prevents anal function
Tumours lower than this margin require abdominal perineal resection where the distal sigmoid, rectum and anus are all removed
Colostomy bag is required
What is the role of clinical and medical oncologists?
Decide on the chemotherapy and/ or radiotherapy treatment to give the patient
What is the difference between clinical and medical oncologists?
Clinical oncologists differ from medical oncologists in that they can also send a patient for adjuvant radiotherapy
May be used to treat rectal cancer
Not usually used to treat colon cancer
What is a medical oncologist?
Specialises in the administration of systemic therapies
What is a clinical oncologist?
Assesses the patient for radiotherapy and systemic therapies
What are common chemotherapy drugs used for the treatment of colon cancer?
5-fluorouracil
Capecitabine
Oxaliplatin
Irinotecan
Tagefur-uracil
