Flashcards
Week 10
Cards in this deck (34)
- 1What is radiation therapy?-Works by damaging the DNA using free radicals within the cancer cells and destroying their ability to reproduce
-Body naturally eliminates the damaged cells
-Normal cells are affected by radiation but can be repaired - 2How can radiotherapy be used?Radical: curative, prostate, bladder, head and neck, oesophagus, gynae, lung
Adjuvant: breast, prostate, lung
Neoadjuvant: rectal
Palliative: symptom control - 3What is gross tumour volume?The cancer that is seen on a scan
- 4What is the clinical target volume?Takes into account microscopic spread from the gross tumour
- 5What is the planned target volume?Takes into account the fact that the radiotherapy set-up is not 100% accurate. This will account for mistakes.
- 6What are fractions?Number of visits to the radiotherapy department for a treatment.
Written as # - 7What is a Gray?-Measurement of a dose
- 8What is normal tissue tolerance?-Limits the maximum dose that can be delivered to the tumour
-Varies between the tissues
-Depends on the type of radiation - 9Why are doses fractionated?Repair: allows normal tissue repair and gradual tumour death with preservation of normal tissue
Redistribution: proliferating cancer cells progress into a more radiosensitive part of the cell cycle (G2/M)
Repopulation: both normal and cancer cells repopulate and can lead to a loss of a cure - 10What is internal radiation therapy?-Places radioactive material into tumour or surrounding tissue
-Sources is placed close to the tumour so large doses hit the cancer cells
-Minimal radiation can be given to the normal tissue
-Can be placed temporarily or permanently in the body - 11Describe the side-effects of radiation therapy?-Skin tenderness
-Doesn't cause hair loss or nausea
-Most begin towards the end of treatment
-Can last for several weeks after the final treatment - 12What are the acute side effects?-Fatigue
-Nausea
-Dermatitis
-Mucositis
-Rash - 13What are some long term side effects?Occurs many months/years later
-Dry mouths
-Taste changes
-Skin fibrosis
-Tooth decay - 14Describe parenchyma and it's role in cancer-Tissues that have a function eg. epithelia, connective tissue, muscle etc
-In cancer, it is composed of malignant cells - 15Describe stroma and it's role in cancer-Everything else
-Provides mechanical and nutrient support to the parenchyma
-Essential for tumour growth
-Contains no mutated DNA - 16How does cancer link to inflammation?-Chronic inflammation pre-disposes to certain cancers such as Barretts metaplasia or liver (due to hepatitis infection)
-Can be due to AI or infectious agents - 17How does daily low-dose aspirin affect your risk of cancer?Decreases risk/metastasis/incidence of colorectal cancer
- 18Describe the seed and soil hypothesisMetastasis is the result of favourable interactions between tumour cells (seed) and the organ microenvironment (soil)
- 19What is the alternate theory for why certain cancers preferentially metastasis to certain tissues?Organ preference is due to anatomy of vascular and lymphatic drainage from the site of primary tumour eg. lungs are a common site of metastasis
- 20'Tumours are wounds that never heal'- Dovrak 1986 What are the consequences of this for tumour development?-Wound healing normally has well defined stages and is self-limiting
-Tumours disguise themselves as wounds
-Tumours also secrete factors that cause persistent angiogenesis and stroma formation - 21What is the importance of hypoxia for tumour cells?-Early barrier to tumour growth
-Angiogenesis and stroma is important for the cancer to survive
-Low oxygen results in anaerobic respiration which needs more glucose (mapped using PET)
-Lactic acid is produced resulting in an acidic environment - 22Interstitial fluid pressure (IFP) is higher in almost all solid tumours. What are the causes/consequences of this?-Vascular abnormalities
-High vessel permeability
-Reduced lymphatic function
This reduces the drug concentrations that can reach the tumour. - 23For tumours to grow, the ECM needs to be remodelled. Why?Allows tumour cell dissemination
- 24For tumours to grow, the ECM needs to be remodelled. How does this occur?-Matrix metalloproteinases (MMPs) break down the ECM allowing remodelling
-High MMP level correlates to a more invasive phenotype and worse outcome - 25What are Cancer Associated Fibroblasts (CAF)?-Part of the stroma
-Increases the metastatic capacity of breast cancer cells
-Increases the progression of pancreatic cancer
-Directly produces factors which promote angiogenesis
-Indirectly attracts pro-inflammatory cells (macrophages) which stimulate cancer cell invasion - 26Describe the role of macrophages in tumoursCan be divided into M1 and M2
-M1: pro-inflammatory and bactericidal. Promotes CD4 T cell differentiation into Th1 and Th17 cells and are anti-cancer
-M2: immunosuppressive and promotes CD4 T cells differentiation into Th2 and Tregs. They are pro-cancer - 27What are Tumour Associated Macrophages (TAMs)?-Tumour hypoxia releases chemoattractants which recruit macrophages
-Promotes angiogenesis
-Infiltrates the tumour at an early stage
-Suppresses other immune cells
-Releases factors that promote metastasis - 28Myeloid derived suppressor cells (MDSCs) are induced by inflammation. What are the consequences of this?-Interferes with innate and adaptive immunity
-Inhibits NK and DC function
-Induces Tregs
-Produces arginase (interferes with T cell function)
-Normally in low levels, but is elevated in patients (correlates with a poor prognosis) - 29Describe the role of NK cells in tumours-Tumour cells have low MHC levels which attracts NK cells
-However these NK cells are anergic and unable to release cytotoxic cytokines
-Suppression of NK cells is caused by TGF-beta - 30Describe the role of CD8 cells in the tumour microenvironment-Contains cytotoxic granules (contain perforin and granzymes) that enter via immune synapses and cause apoptosis
-Presence correlates with a good prognosis - 31Describe the role of Th1 cells in the tumour microenvironment-Normally defends against viruses
-Cells are beneficial and activate macrophages
-Also kills tumour cells - 32Describe the role of Th2 cells in the tumour microenvironment-Normally defends against parasites
-Thought to be a poor prognostic marker - 33Describe the role of Th17 cells in the tumour microenvironment-May be involved in cancer development
-Inflammation cause can promote cancer development
-Also can attract MDSCs and promote angiogenesis
-Linked to a poor prognosis in some cancers - 34Describe the role of Treg cells in the tumour microenvironment-Prevents AI
-Produces adenosine which suppresses T cells
-Increased numbers correlates with a poorer prognosis