Cancer Treatment
·
Treatment objectives:
o Cure
o Prolong life expectancy
o Relieve symptoms
·
Treatment modalities:
o Chemotherapy
o Radiotherapy
o Symptomatic/Supportive
·
No role for radiotherapy in colon
· Adjuvant chemotherapy:
o Improves 5 year survival over surgery alone from 50 to 60/65% (but can‟t predict who will benefit)
o Quality
of life (side effects of cancer are pretty severe, chemo reduces these)
o Given after surgery
o Six months of 5FU
o Currently given to:
§ Dukes C: All patients (C1 = Muscularis propria + lymph node, C2 = serosa + lymph node)
§ Dukes B2 (serosa): High risk groups, perforation, invasion of adjacent
organs, diploid tumours
·
Rectal cancer:
o No serosa around rectum – cancer infiltrates straight into fat – harder to get clear resection margins
o Radiation in rectal cancer good: but ® impaired function and may irradiate small bowel ® fibrosis. Try and predict who needs irradiation and do it pre-operatively
·
Palliation: hospice +
chemotherapy better quality of life than hospice alone
·
Can‟t cure metastases ® aim of
treatment is local control
·
Options:
o Two options (similar long-term survival):
§ Removal of the lump + radiation therapy (significant ¯ in local
recurrence)
§ Mastectomy (or radical mastectomy) + reconstruction
o +/- Radiotherapy (planned to limit dose to the heart, lung or opposite
breast
o +/- Tamoxifen (anti-oestrogen)
·
Surgery:
·
Mastectomy Breast
Conservative
·
Patient preference Patient
preference
·
Large tumour or Large tumour/breast ratio Small tumour or small tumour/breast
ratio
·
Multiple tumours Single
tumour
·
+ive margins Focal
microcalcification
·
Previous breast RT -ive
margins
·
Pregnancy, etc, etc
·
Most common metastasis is in the
bone. Bisphosphonates ® slow
osteolysis
·
Risk factors for recurrence in
breast cancer (Þ consider adjuvant chemo):
o Axillary node status (strongest predictor)
o Tumour size (> 1 cm)
o Histological tumour type and grade
·
Adjuvant Chemotherapy:
o Approx 25 – 30% ¯ risk of recurrence, 15 – 20% ¯ risk of death. Improves long term survival in node positive and node negative disease
o 4 to 6 courses over 3 – 6 months optimal
o 2 agents better than one: eg
§ AC: Adriamycin (an anthracycline) and Cyclophosphamide. „Gold standard‟.
Adriamycin causes vomiting and wasn‟t used so much until 5HT3 antagonists were
available
§ CMF: Cyclophosphamide, Methotrexate and Fluorouracil (another „Gold Standard‟)
·
Hormone Therapy:
o Aim: prevent breast cancer cells from receiving stimulation from
oestrogen
o Only is oestrogen receptor sensitive
o Oestrogen deprivation:
§ Block oestrogen receptor: eg Tamoxifen – antagonist. Taken for 5 years. Side-effects:
·
Largely well tolerated
·
1 in 3 have post menopausal
flushes, vaginal dryness/discharge
·
Initial nausea, weight gain
· Rare retinopathy
· Agonist in the uterus ® endometrium ® risk of endometrial carcinoma (1 in 1000, usually curable)
· PE/DVT (1 – 2 %)
§ Suppress synthesis: aromatase inhibitors (work in adipose tissue, eg in
post menopausal women), LHRH agonist (pre-menopausal, switches off the ovary)
§ Destroy ovaries (surgery or RT)
o Leads to ¯recurrent, ¯ 40% incidence of contralateral breast cancer (although absolute risk
low)
·
Superficial X-ray: for skin
cancers
·
Cobalt: no longer used in the
west. Max 1.2 MV
·
Linear accelerators:
o 6 MV to 18 MV
o Skin sparring
o Produces electrons and photons. Biological effect of photons is to create free radicals
o Does lots of damage to the cell – but only damage which affects
reproductive integrity is DNA damage
o Most DNA damage is repaired within 6 – 8 hours, but if lots of damage
then non-repair
o More damage is done to cells in G2 (ie in mitosis) as DNA is super
coiled
·
Effective use requires:
o Good planning: how to maximise dose to the lesion while minimising dose
to unaffected tissue
o Immobilising the patient
·
Use of multiple fractions (ie
lots of small doses) spares normal tissue as this has time to repair, but
tumour tissue doesn‟t repair so well
·
Uses:
o Aim is curative in head and neck, skin, cervix
o Anal (with chemo), rectal (with surgery)
o Adjunct in lung, stomach cancer
·
Toxicity:
o Acute: builds up during treatment and settles within ~ 6 weeks
§ Affects rapidly dividing cells and secretory function
§ Skin: erythema, desquamation
§ Mouth: mucositis and dryness
§ Gut: diarrhoea, colic, ileus
§ Bladder: cystitis
§ Marrow (only if widespread dosing): leukopaenia, thrombocytopenia
o Late: Months to years
§ Due to healing with fibrosis or aging of tissues
§ Affects slowly or non-dividing cells and causes permanent damage
§ Skin: Telangiectasis, fibrosis
§ Mouth: Dryness (¯parotid function), caries, osteoradionecrosis
§ Gut: stricture, fistula
§ Bladder: contracture, haematuria
§ Nerves: myelitis, necrosis, neuropathy
·
Systemic treatment with single or
multiple agents
·
Damages DNA/RNA protein synthesis
® cell death/apoptosis. Not tumour
specific
·
Predictable side effect depending
on the schedule. Side effect management
has improved greatly
·
Can be oral, sc, im, iv,
continuous iv
·
Adjuvant Treatment = after local
therapy has removed cancer but where there is a statistical chance of relapse
(eg due to micro metastases)
·
Uses:
o Can be curative in: lymphoma (esp Hodgkin‟s), leukaemia (including ALL),
sarcomas of childhood, Germ cell tumours (Testicular teratoma, Seminoma), etc
o Adjuvant in breast, large bowel and ovarian cancer
o Prolongation of life: Ovarian, lung (small cell lung cancer is sensitive
to chemotherapy), bowel, breast
o Relief of symptoms: shortness of breath, pain/discomfort, local disease
o Not in melanoma, renal cell carcinoma
·
Side effects:
o General:
§ Feeling terrible till 2 – 3 days later
§ Nausea: 5HT3 antagonists to help
§ Lethargy, anorexia
o Affect on fast growing tissues:
§ Mucous membranes: mouth ulcers, diarrhoea
§ Hair loss: not inevitable (depends on regime) but always temporary
§ Bone marrow: myelosuppression, anaemia, neutropenia, thrombocytopenia
o Irritant effects: haematuria, sore eyes
o Neutropenia: typically 1 –3 weeks following.
o ¯Fertility
(especially in men) but no risk of future fetal abnormality (unless pregnant at
the time). NOT a reliable contraceptive
·
Hormones
·
Immunotherapy
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