S10) Incidence, Prognosis & Treatment of Neoplasms Flashcards
Outline the incidence of different malignant neoplasms in the UK
Breast, lung, prostate and bowel carcinomas accounted for over half of all new cancers in the UK (53%)
Outline the incidence of malignant neoplasms in terms of age
- The great majority is diagnosed in people aged over 65 but only a small proportion in people up to age 24
- In children younger than 14, leukaemias, CNS tumours and lymphomas are most common
What is the significance of understanding survival rates and mortality for cancer?
Survival rates and mortality rates indicate how aggressive a cancer is
The survival rates for different malignant neoplasms in the UK is variable.
State the 5 year survival rates for the following:
- Testicular cancer
- Melanoma
- Breast cancer
- Pancreatic cancer
- Lung cancer
- Oesophageal cancer
- Testicular cancer (98%)
- Melanoma (90%)
- Breast cancer (87%)
- Pancreatic (3%)
- Lung (10%)
- Oesophageal cancers (15%)
What is the biggest cause of cancer-related deaths in the UK?
Lung cancer
Which 7 factors should one consider to predict the outcome from malignant neoplasms?
- Age
- General health status
- Tumour site
- Tumour type
- Tumour grade (i.e. differentiation)
- Tumour stage
- Availability of effective treatments
Describe the use of tumour stage
Tumour stage is a measure of the malignant neoplasm’s overall burden
The commonest method for assessing the extent of tumour is the TNM staging system that is standardised across the world.
Outline TNM staging
- T refers to the size of the primary tumour (T1 –T4)
- N refers to the extent of regional node metastasis (N0 to N3)
- M refers to the extent of distant metastatic spread (M0 or M1)
For a given cancer the T, N and M status are then converted into a stage from I to IV.
Outline how cancers are staged from I - IV using TMN staging
- Stage I is early local disease
- Stage II is advanced local disease (i.e. N0, M0)
- Stage III is regional metastasis (i.e. any T, N1/more, M0)
- Stage IV is advanced disease with distant metastasis (i.e. any T, any N and M1)
Lymphoma has its own special system called Ann Arbor staging.
Outline this form of tumour staging
- Stage I indicates lymphoma in a single node region
- Stage II indicates two separate regions on one side of the diaphragm
- Stage III indicates spread to both sides of the diaphragm
- Stage IV indicates diffuse or disseminated involvement of one or more extra-lymphatic organs e.g. bone marrow or lung
Dukes staging has been used to determine survival rates for colorectal carcinoma.
Outline this form of tumour staging
- Dukes’ A: invasion into but not through the bowel
- Dukes’ B: invasion through the bowel wall
- Dukes’ C: involvement of lymph nodes
- Dukes’ D: distant metastases but TNM staging is the preferred system worldwide
Describe the use of tumour grade
- Tumour grade describes the degree of differentiation of a neoplasm
- It is more important for planning treatment and estimating prognosis in certain types of malignancy e.g. soft tissue sarcoma, primary brain tumours, lymphomas, breast and prostate cancer
Outline the tumour grading system used for squamous cell carcinoma and colorectal carcinoma
- G1 is well-differentiated
- G2 is moderately differentiated
- G3 is poorly differentiated
- G4 is undifferentiated or anaplastic
Some cancers use an internationally recognised formal grading system.
Identify and describe the grading system used for breast carcinoma
Bloom-Richardson system – assesses tubule formation, nuclear variation and number of mitoses
How can cancer be treated?
Cancer can be treated by surgery, radiotherapy, chemotherapy, hormone therapy and treatment targeted to specific molecular alterations
Surgery is the mainstay of treatment for most cancers but the precise role for each type of treatment varies for each cancer and also depends on the cancer’s stage.
Describe the surgical treatment of cancer in terms of adjuvant and neoadjvant treatment
- Adjuvant treatment is given after surgical removal of a primary tumour to eliminate subclinical disease
- Neoadjuvant treatment is given to reduce the size of a primary tumour prior to surgical excision
Explain how radiation therapy kills proliferating cells by triggering apoptosis or interfering with mitosis
X-rays, etc kill rapidly dividing cells (especially in G2 phase):
- High dosage causes either direct or free-radical induced DNA damage that is detected by the cell cycle check-points, triggering apoptosis
- Double-stranded DNA breakages cause damaged chromosomes that prevent M phase from completing correctly
How is normal tissue damage minimised in the radiotherapy treatment of cancer?
- Radiotherapy is focused on the tumour with shielding of surrounding healthy tissue
- It is given in fractionated doses to minimise normal tissue damage
Several classes of chemotherapy agents exist.
Identify them
- Antimetabolites
- Alkylating and platinum-based drugs
- Antibiotics
- Plant-derived drugs
Chemotherapy drugs affect proliferating cells in different ways.
Explain the action of antimetabolites
Antimetabolites mimic normal substrates involved in DNA replication e.g. Fluorouracil
Chemotherapy drugs affect proliferating cells in different ways.
Explain the action of alkylating and platinum-based drugs
Alkylating and platinum-based drugs cross-link the two strands of the DNA helix e.g. cyclophosphamide and cisplatin
Chemotherapy drugs affect proliferating cells in different ways.
Explain the action of antibiotics
Antibiotics act in several different ways e.g. doxorubicin inhibits DNA topoisomerase, which is needed for DNA synthesis, while bleomycin causes double-stranded DNA breaks
Chemotherapy drugs affect proliferating cells in different ways.
Explain the action of plant-derived drugs
Plant-derived drugs block microtubule assembly and interferes with mitotic spindle formation e.g. vincristine
Hormone therapy is relatively non-toxic treatment for certain malignant tumours.
Explain the use of selective oestrogen receptor modulators to treat breast cancer
- Selective oestrogen receptor modulators bind to oestrogen receptors, preventing oestrogen from binding e.g. tamoxifen
- They are used to treat hormone receptor-positive breast cancer
