incidence, prognosis and treatment of cancer Flashcards
What are the 4 most common cancers in the uk?
breast, lung, prostate and bowel
What are the most common cancers in children under the age of 14?
- leukaemia’s
- CNS tumours
- lymphomas
Which cancers carry a very good 5 yr survival rate?
- testicular
- melanoma
- breast
- prostate
Which cancers carry a very bad 5 yr survival rate?
- pancreatic
- lung
- oesophageal
What factors must be considered when trying to predict the outcome of a cancer?
- age
- general health
- tumour site
- tumour type
- grade (differentiation)
- stage (size/ spread)
- availability of effective treatments
What is the common system for assessing tumour burden?
TNM staging (T= size of primary tumour, N= regional spread via lymph nodes, M= distant metastatic spread via blood)
Explain how scored are given for each section of the TNM staging system?
T is by size (1,2,3,4)- but it varies
N0 = no lymph spread, N1= regional spread to one lymph node, N2= spread to many nearby lymph nodes
M0= no distant metastasis, M1= distant metasis present
Explain the staging of tumours as I, II, III, IV
I= early local disease II= advanced local disease (N0, M0) III= regional metastasis (N1 or more with M0) IV= advanced with distant metastasis (M1)
What special system is used to stage non-solid lymphomas?
Ann Arbor staging
How does Ann Arbor staging work? (for non-solid lymphomas)
I= single lymph node
II= 2 or more lymph nodes effected but on same side of diaphragm
III=lymph nodes on both sides of diaphragm affected
IV= involvement of one or more extra lymphatic organs such as bone marrow or lung
What system is used to stage colorectal carcinoma?
Dukes staging
How does Dukes staging work? (for bowel cancer)
A= invasion into but not through bowel B= invasion through cell wall C= involvement of lymph nodes D= distant metastasis
What is grading? Describe the system used
- how well differentiated the cancer is G1= well differentiated G2= moderately diff G3= poorly diff G4= anaplastic/undifferentiated
What ways can cancer be treated?
- chemotherapy
- radiotherapy
- surgery
- hormone therapy
- targeted molecular adaptations
What is meant by adjuvant and neoadjuvant therapy?
adjuvant: treatment given after surgery to eliminate subclinical micrometastasis
neoadjuvant: treatment given to reduce the size of the primary tumour prior to surgery
Describe how radiotherapy is given and how it works (4)
- given in fractioned doses to allow time for healthy cells to recover/minimise normal tissue damage
- causes direct or free radical damage to DNA
- especially in cells in G2 phase (therefor targets rapidly dividing tissues more)
- DNA damage such as DS breaks induces apoptosis as dose is so high that lots of damage cannot be repaired
What types of chemotheraputic agents are there? (4)
- Antimetabolites: analogues of normal substances eg fluorouracil inhibits DNA replication as replaces thymine
- Alkylating agents: cross link DNA (cisplatin)
- Antibiotics: many ways- inhibits DNA synthesis mainly (doxorubicin)
- Plant derived drugs block microtubule assembly and interfere with spindle formation (vincristine)
Give an example of a hormone therapy targeting cancers
- tamoxifen (SERM) binds to oestrogen receptors preventing oestrogen binding so treats oestrogen receptor positive breast cancer
- androgen blockades can treat some prostate cancers
What is the benefit of hormone therapy?
- non toxic as very selective to cancer cells
Give 2 examples of oncogenes being targeted to treat cancer
- Herceptin/ trastuzumab blocks HER2 receptor so no inactivates oncogene
- Gleevac/imantinib prevents fusion of two proteins in chronic myeloid leukaemia which cause creates an oncogene
Give an example of a hormone tumour marker
human chorionic gonadotrophin released from testicular tumours - measured for diagnosis
How are tumour markers useful?
- can sometimes be used for diagnosis (although not specific or sensitive enough really)
- mainly used for monitoring tumour burden
What is the limitations of screening programs
- pick up before would even be a problem (lead time bias) so looks like longer 5 yr survival but really isn’t
- pick up people whos are so slow growing they’d never be a problem (over-diagnosis)
- pick up slow growing ones more commonly than fast growing (length time bias)
Who are screening programmes meant for?
Healthy people with no symptoms in order to detect cancers as early as possible when chance of cure is highest.
