Cancer in Children Flashcards
Describe the epidemiology of cancers in children
- Cancer affects 1/500 children under the age of 15
- Leading course of death in this age group
- Distinct spectrum of malignancies at different ages
what do certain childhood magnifies reflect
- Certain childhood malignancies reflect abnormal processes of embryonic development
some genetic disorders can..
- Some genetic disorders predispose to childhood cancer
describe the percentage changes in - leukaemia - lymphomas - carcianoma - renal tumours - neuroblastoma in those aged under 14 to those aged 15-19
- Leukaemia is 31.1% in 0-14 years but goes down to 13.8% in 15-19 years
- Lymphomas are 10% in under 14s but 20% in 15-19 year olds
- Carcinomas are 4% in less than 14 years but increase in 19.6% for 15-19 year olds
- Renal tumours decrease as you get older
- Neuroblastoma decrease as you get older as well
What problems can cancers affect later on
Growth and development Psychosical Organ function Cacner Fertility and reproduction
describe the different problems that cancer can cause later on
Growth and development - skeletal maturation - linear growth • Emotional & social maturation • Intellectual function • Sexual development
Psychosical • Mental health • Education • Employment • Health insurance • Chronic symptoms • Physical/body imag
Organ function • Cardiac • Endocrine • GI & hepatic • Genitourinary • Musculoskeletal • Neurological • Pulmonary
Cancer
• Recurrent primary cancer
• Subsequent neoplasms
Fertility and reproduction
• Fertility
• Health of offspring
• Sexual functioning
Childhood cancers have fewer..
mutations than adults tumours
what is the most common cancers in 0-14 year olds
- Leukaemia (31.1%),
- CNS (25.4%),
- Lymphomas (10%).
what is the most common cancer in 15-19 year olds
- Lymphomas (20.7%),
- Carcinomas and Melanoma (19.6%)
- CNS (18.7%)
- Leukaemia (13.8%).
why is chemotherapy especially toxic in children
Chemotherapy: especially toxic in children because they have many dividing cells.
Radiation: can damage growing cells and lead to the development of other tumours.
what do tumours in children arise from
- they arise in cells that are naturally undergoing rapid developmental growth that have fewer breaks on their proliferation than cells in adults
what leads to altered gene expression
- cancer can arise from accumulation of genetic aberrations in somatic cells
- these aberrations consist of mutations and chromosome defects
- epigenetic aberrations are also present
- these all lead to altered gene expression
How are oncogenes activated
by gain of function
in order for an oncogene to work how many Alleles need to be activated
- Dominant (activation of one allele sufficient to have an effect)
what is an oncogene
• Gene that encodes protein capable of inducing cancer
what causes an gain of function in an oncogene
- Mutation
- Chromosome translocation
- Gene amplification
- Retroviral insertion
list examples of oncogenes
- KRAS
- NRAS
- BRAF
- ALK
- ABL1
what causes activation of a tumour suppressor gene
loss of function
how many alleles need to be present for tumour suppressor genes to be activated
- Act when there is inactivation of both alleles necessary (recession)
what causes loss of function in tumour suppressor genes
- Mutations
- Deletions
- DNA methylation (epigentic)
These can cause predisposition to cancer
- DNA methylation (epigentic)
list examples of tumour suppressor genes
- RB
- WT1
- BRCA1
- BRCA2
- APC
- NF1
describe the two hit model
- two copies of a gene need to be mutated in order for cancer to develop
- you can already have an fault mutation but the other gene works properly
- then there needs another insult to take place for cancer to be developed
- therefore there is no functional gene lift
what is wilms tumour also called
nephoblastoma
describe how a wilms tumour presents
- it is often asymptomatic but the abdominal mass can be felt without metastasis
How does a wilms tumour spread
- Spreads by growth, or via lymphatics or blood stream
is wilms tumour heritable
• Heritable in 1/20 of patients.
o Therefore, often bilateral.
if you have wilms tumour what syndromes are you predisposed to
WAGR
- Wilms tumour
- Aniridia
- Genito-urinary abnormalities
- Mental retardation
Can also have
- Beckwith-wiederman syndrome (BWS)
what are the cellular origins of wilms tumour
• Arises from the pluripotent embryonic renal precursors.
• Classically contains three cell types present in the embryonic kidney:
o Blasterma.
o Epithelia.
o Stroma.
what does wilms tumour closely resembl e
- Closely resembles developing nephrogenic mesenchyme
what are the somatic and germ like alternations you can have with wilms tumour
Somatic genetic alternations:
- Inactivated WT1, WTX, TP53 genes
- Activated CTNNB1 gene
- Epigenetic alterations at IGF2/H19 locus
Germline alterations
- WT1 gene (CAN BE PART OF wagr)
- IGF2/H19 (can be part of BWS)
why is the WT1 gene linked to kidney tumours (wilms tumour)
- WT1 plays a crucial role in ureteric branching
- WT1 and the WNT pathway (activated by beta catenin) have key roles in epithelial induction of the metanephric mesenchyme
what is the treatment of wilms tumour
• Surgery then chemotherapy (or other way around).
o Combination chemotherapy shows promising results.
• Use of radiotherapy is decreasing.
- genetic counselling is used if genetic predisposition is suspected
what age group does retinoblastoma occur in
• Tumour of the retina.
o Usually occurs in children <5
what gene is important in a mutation in retinoblastoma
- Germline mutation of RB1 gene
is retinoblastoma heritable
• Heritability in ~30% of cases.
what are the symptoms to retinoblastoma
- Leukocoria – white pupil when light is shone onto it
- Eye pain
- Redness
- Vision problems
describe the cellular origins of the retinoblastoma
- Originates from cone precursor cells.
* Signalling pathways promotes cell survival after loss of RB1.
where does the retinoblastoma grow
- Tumour groups in the vitreous humour of the eye
describe what the RB1 usually does
- During the G1 phase the RB1 is either hyperphosphorylated or unphosphorylated
- In the unphosphorylated state RB1 binds to E2F and the cell cannot progress to the G1-S phase
- When the RB1 becomes phosphorylated it releases E2F
- E2F drives S phase
how does RB1 cause cancer
Cancer Cells without RB1: if you don’t have RB1: E2F is free to induce G1-S transition.
Activation of MYCN: proliferation.
How do you treat retinoblastoma
- small tumours = cryotherapy, laser therapy or thermotherapy is used
- in more advanced tumours - chemotherapy, surgery and radiation is used
- Systemic or intraocular chemotherapy can be used to shrink tumours before cryotherapy or laser therapy
what is a neuroblastoma
• Tumour of the sympathetic nervous system, usually arising in the adrenal gland or sympathetic ganglia
what age is a neuroblastoma commonly found in
• Most common cancer in the first year of life
how does the neuroblastoma spread
- via lymphatics and blood stream
what are the prognostic factors of a neuroblastoma
stage, age, MYCN amplification, DNA ploidy, histopathology
where does neuroblastoma metastasise to
metastatic disease to liver and skin
what are the cellular origins of a neuroblastoma
• Derived from sympatho-adrenal linage of the neural crest during development.
o Originates from incompletely committed precursor cell.
• Key genes: MYCN, ALK.
what are two common genes to do with a genetic predisposition to neuroblastoma
- Some are very rare, also common alleles which have some predispotion
- Two which are commonly known are ALK and PHOX2B
what can cause a high risk, low risk and hereditary cause of neuroblastoma
High Risk
• MYCN amplification (transcription factor), ATRX, ALK mutations.
o Near diploid/tetraploid karyotype.
Low Risk/Intermediate-Risk/Stage 4S
• Numerical chromosome gains.
Hereditary
• Germline ALK mutations.
how do you calculate a prognosis for neuroblastoma
- less than 10 copies of NMYC high prognosis, more than 10 copies of N-MYC poor prognosis
what is the treatment for a neuroblastoma
- Surgery, chemotherapy, radiation therapy
- High risk disease – high dose chemotherapy and stem cell transplantation
- Targeted therapy – crizotinib against ALK mutations
- Immunotherapy
what are chemotherapy related complications
hearing loss, infertility, cardiac toxicity and second malignancies
what is the most common malignancy in children
Acute lymphoblastic leukaemia
How does the patient present with acute lymphoblastic leukaemia
- Bruising/bleeding.
- Pallor or fatigue due to anaemia.
- Infection due to neutropenia.
where does acute lymphoblastic leukaemia spread
liver, spleen, lymph nodes and mediastinum
what does acute lymphoblastic leukaemia cause
Clonal expansion of immature lymphocytes = lymphoblasts/blast cells
What are the cellular origins in acute lymphoblastic leukaemia
• Traced back to haematopoiesis.
Pro-B: CD19+ on the cell surface.
Pre-B: CD19+ and CD10+.
These have very specific genetic changes that cause different types of leukaemia’s.
• ALL: MLL translocation (19)
• TEL-AML1 translocation (19 and 10).
what is the molecular pathology of acute lymphoblastic luekamiea
- Specific genetic alterations are associated with phenotypic subtypes of ALL
- Incidence of the subtypes varies with age
- Certain genetic alterations have been found in newborn babies who contract leukaemia a few years later
What is the treatment for acute lymphoblastic leukaemia
• Patients stratified into risk groups according to clinical, biological and genetic features
• Therapies of varying intensities applied to different risk groups
• Standard treatment phases:
-Induction (e.g.Vincristine, Corticosteroid, L-asparaginase, Anthracycline)
- Consolidation; CNS directed treatment(e.g.Cyclophosphamide, Cytarabine, Mercaptopurine, Methotrexate; Dexamethasone)
- Maintenance(e.g. Mercaptopurine, Methotrexate) - Bone marrow transplantation
describe the role of the two step model for the role in infection in acute lymphoblastic leukaemia
- Inherited genetic background
- Convert pre-leukaemia
- Massive expansion of the immune system
- Accumulation of the B cell
what are high risks groups for cancer
- Any tumour diagnosed in the perinatal period suggests a genetic predisposition syndrome.
- Bilateral or multifocal disease, associated with congenital malformations.
- Cancer in close relatives.
• Same rare tumour in more than one family member,
o e.g. familial Retinoblastoma
• Different types of tumours occurring in family members
o e.g. Li-Fraumeni syndrome
