Oncology Flashcards
What is the mechanism of action of Rasburicase as prophylaxis for tumour lysis syndrome?
Promotes catabolism of uric acid to water soluble allantoin.
Bleomycin
Bleomycin is a cell-cycle specific glycopeptide antibiotic that arrests rapidly dividing cells at the early G2 stage.
Cytarabine
Cytarabine is a cell-cycle specific pyrimidine analogue that inhibits DNA polymerase leading to arrest of DNA synthesis at the S stage.
Asparaginase
Asparaginase is a cell-cycle specific enzyme that depletes leukemic cells of asparagine thereby arresting growth at the G1 stage.
Which genetic marker is the strongest prognostic factor in predicting overall survival in patients with neuroblastoma?
MYCN amplification represents the strongest independent adverse genetic prognostic factor. Gene amplification of MYCN acts as an oncogenic driver causing neoplastic change in neural crest-derived derived cells.
Reed-Sternberg cells with a surrounding infiltrate of lymphocytes, eosinophils, macrophages, plasma cells and fibroblasts.
Diagnosis of Hodgkin Lymphoma is established by demonstrating Reed-Sternberg Cells on biopsy. These are germinal centre B-cells that cannot synthesise immunoglobulin but instead secrete a range of cytokines important in the maintenance of the heterogeneous lymph node infiltrate.
Hodgkin Lymphoma commonly presents in teenagers with lymphadenopathy and ‘B symptoms’ (night sweats, fever, weight loss).
unilateral submandibular lymphadenopathy. The lymph node has gradually increased in size to 4cm in diameter, despite a course of penicillin. His mother is concerned as she has recently noted a change in colour of the overlying skin to pink/purple and pustular discharge through a break in the skin.
Infection with non-tuberculous mycobacterium (such as mycobacterium avium) can be a cause of sub-acute lymphadenitis in children. Classical presentation is of a slowly enlarging, non-tender, unilateral lymph node (most commonly submandibular) that is not responsive to antimicrobials targeted at staphylococcus/streptococcus. Lymph nodes progress to become tethered to the skin which changes colour to pink/violet and develops a draining sinus. The patient is generally systemically well and has normal blood counts and inflammatory markers.
Management involves surgical excision +/- anti-mycobacterial therapy.
Bartonella henslae
Cat scratch disease typically presents in children with lymphadenitis around two weeks post-scratch or bite in a lymph node proximal to the site of inoculation. The illness can progress to systemic involvement of the spleen, liver, eyes and CNS. Azithromycin and trimethoprim-sulphamethoxazole are effective treatment options.
The principal mode of action of folinic acid in this context is:
provision of reduced folates for nucleic acid synthesis.
Dihydrofolate reductase converts dihydrofolate into tetrahydrofolate, a methyl group shuttle required for the de novo synthesis of purines, thymidilic acid, and certain amino acids.
Cancer chemotherapeutic agents like methotrexate (4-amino, 10-methyl folic acid) and aminopterin (4-amino, folic acid) are structural analogs of folic acid and inhibit dihydrofolate reductase. This interferes with maintenance of the folate pool and thus of de novo synthesis of purine nucleotides and of dTMP synthesis.
Which non-HLA donor characteristic is associated with better overall survival post HSCT?
Age. Following histocompatibility match in an unrelated donor, donor age is the next factor which impacts overall survival. There is a 5.5% increase in the hazard ratio for mortality following HSCT for every 10-year incremental increase in donor age.
