14.3 Anemias & Oncology Supportive Care
Key Takeaways
Iron deficiency in men and postmenopausal women needs investigation for GI blood loss; oral iron is taken once daily or on alternate days, separated from levothyroxine and other chelating drugs.
Continue oral iron for about 3 months after hemoglobin normalizes, and use IV iron for intolerance, malabsorption or advanced CKD.
High-dose oral vitamin B12 (1,000 to 2,000 mcg daily) is effective even in pernicious anemia, and B12 deficiency must be excluded before treating with folate alone.
Highly emetogenic chemotherapy such as cisplatin needs an NK1 antagonist, a 5-HT3 antagonist, dexamethasone and olanzapine.
Fever of 38.3°C or more after chemotherapy may be febrile neutropenia and needs immediate assessment and IV antibiotics.
Anemias & Oncology Supportive Care
Anemia is a common finding in community practice. The pharmacist's role is to support the right replacement therapy and to recognize when an underlying cause needs investigating. Most patients with cancer now receive at least part of their treatment at home. Community pharmacists therefore manage antiemetics, oral anticancer drugs, infection warnings and safe handling.
1. Iron-Deficiency Anemia
- Diagnosis: microcytic anemia with ferritin below 30 µg/L. Ferritin can be falsely normal in inflammation, where values up to about 100 µg/L may still mean iron deficiency.
- Look for the cause: in men and postmenopausal women, iron deficiency is GI blood loss until proven otherwise and needs referral for investigation. Other causes are heavy menstrual bleeding, pregnancy, malabsorption (celiac disease, bariatric surgery), and NSAID or anticoagulant-related bleeding.
- Oral iron:
- Elemental iron content: ferrous sulfate 300 mg ≈ 60 mg; ferrous gluconate 300 mg ≈ 35 mg; ferrous fumarate 300 mg ≈ 100 mg.
- Dose once daily, or on alternate days. Each dose raises hepcidin for about 24 hours, so splitting doses through the day adds GI effects but little absorption.
- Take on an empty stomach, with water or a vitamin C source. Take with food if GI upset limits adherence.
- Separate iron from levothyroxine (about 4 hours), fluoroquinolones, tetracyclines, calcium, antacids and bisphosphonates. PPIs reduce absorption.
- Expected response: reticulocytes rise within about 7 to 10 days and hemoglobin by about 10 to 20 g/L within 2 to 4 weeks. Continue for about 3 months after hemoglobin normalizes to rebuild stores.
- Counsel that dark stools are expected. Black, tarry, sticky stools with weakness suggest bleeding and need assessment.
- IV iron (iron sucrose, ferric derisomaltose, ferric carboxymaltose) is used for intolerance, malabsorption, ongoing losses, advanced CKD, or the need for rapid repletion before surgery.
2. Vitamin B12 and Folate Deficiency
- Vitamin B12 deficiency causes macrocytic anemia and neurological symptoms: neuropathy, cognitive change and gait problems.
- Causes: pernicious anemia, gastric surgery, a strict vegan diet, and long-term metformin or PPI use. Check B12 periodically in long-term metformin users.
- Treatment: high-dose oral cyanocobalamin (1,000 to 2,000 mcg daily) works even in pernicious anemia, because passive absorption does not need intrinsic factor. IM injections are used for severe deficiency or neurological involvement.
- Folate deficiency: folic acid 1 to 5 mg daily. Rule out B12 deficiency first. Folate alone can correct the anemia while neurological damage from B12 deficiency progresses.
- Pregnancy planning: folic acid supplementation starts before conception (section 15.3).
3. Chemotherapy-Induced Nausea and Vomiting (CINV)
Prophylaxis depends on the emetogenic risk of the regimen:
| Emetic risk | Example agents | Recommended prophylaxis (acute phase) |
|---|---|---|
| High (> 90%) | Cisplatin; anthracycline plus cyclophosphamide | NK1 antagonist (aprepitant or fosaprepitant) + 5-HT3 antagonist (ondansetron, granisetron, palonosetron) + dexamethasone + olanzapine |
| Moderate (30–90%) | Oxaliplatin, irinotecan, carboplatin | 5-HT3 antagonist + dexamethasone (add an NK1 antagonist for carboplatin at higher doses) |
| Low | Taxanes, gemcitabine, 5-FU | A single agent (dexamethasone or a 5-HT3 antagonist) |
| Minimal | Many monoclonal antibodies | No routine prophylaxis |
- Delayed nausea (days 2 to 4) is treated with dexamethasone and/or olanzapine. Ondansetron adds little in the delayed phase.
- Breakthrough: olanzapine, or a dopamine antagonist such as metoclopramide or prochlorperazine (watch for extrapyramidal reactions). Doses are scheduled, not left until vomiting starts.
- Anticipatory nausea: prevented by good control from the first cycle; lorazepam before treatment.
- Practical pearls:
- Ondansetron: constipation, headache and QT prolongation.
- Dexamethasone: in the morning (insomnia), and monitor glucose.
- Aprepitant: CYP3A4 interactions. It raises dexamethasone levels (reduce the dexamethasone dose), lowers warfarin effect, and reduces hormonal contraceptive efficacy for 28 days.
- Missed doses: a patient on scheduled before-meal metoclopramide who misses the breakfast dose and will be home just before lunch should skip the missed dose and take the next scheduled one. Missed doses are taken when remembered only if the next dose is not due soon, and doses are never doubled. PEBC's sample items use exactly this case.
4. Febrile Neutropenia and Other Supportive Care
Warning
Febrile neutropenia is an emergency. Fever (a single temperature of 38.3°C or higher, or 38.0°C sustained over an hour) with an absolute neutrophil count below 0.5 × 10⁹/L, or expected to fall below it, needs immediate assessment and empiric IV antibiotics within about an hour. Patients should not treat a fever with acetaminophen at home without calling their oncology team, because it can mask fever.
- Granulocyte colony-stimulating factors (filgrastim, pegfilgrastim, and their biosimilars) are used as primary prophylaxis when a regimen's febrile neutropenia risk is 20% or higher, or 10 to 20% with patient risk factors. Bone pain is common and responds to acetaminophen or loratadine.
- Oral anticancer drugs:
- Hazardous handling: wash hands, wear gloves for caregivers, do not crush or split, and return unused drugs to the pharmacy.
- Adherence and dosing: check for complex schedules (for example, capecitabine twice daily after meals for 14 days of a 21-day cycle).
- Interactions: many kinase inhibitors are CYP3A4 substrates, and some need gastric acid to dissolve, so PPIs reduce absorption. Capecitabine raises warfarin effect.
- Mucositis: bland rinses (salt and baking soda in water), soft toothbrush, no alcohol-based mouthwashes.
- Tumour lysis syndrome prevention in high-risk cancers: hydration plus allopurinol, or rasburicase (contraindicated in G6PD deficiency).
- Hypercalcemia of malignancy: IV hydration, then zoledronic acid or denosumab.
- Cancer-associated thrombosis is covered in section 8.3.
A 52-year-old woman with iron-deficiency anemia takes levothyroxine 100 mcg every morning. She is prescribed ferrous sulfate 300 mg. Which counselling is most appropriate?
Take iron once daily or every other day, 4 hours from levothyroxine, for 3 months after hemoglobin normalizes.
Take both together on waking to make them easier to remember.
Take the iron with a glass of milk to reduce stomach upset, because dairy does not affect iron absorption.
Expect hemoglobin to normalize within 3 days, then stop the iron.
A patient is to receive high-dose cisplatin for the first time. Which antiemetic prophylaxis regimen best matches current recommendations for the acute phase?
Metoclopramide as needed, starting only after vomiting begins
Ondansetron alone, given 30 minutes before chemotherapy on day 1 only
NK1 antagonist + 5-HT3 antagonist + dexamethasone + olanzapine
Dexamethasone alone.
A patient who received chemotherapy 9 days ago calls the pharmacy. They feel unwell and have a temperature of 38.4°C. What should the pharmacist advise?
Take acetaminophen every 4 hours and call back if the fever lasts more than 3 days or gets higher.
Seek emergency care or call the oncology team now: possible febrile neutropenia.
Increase fluid intake and rest at home, because post-chemotherapy fever is expected.
Start leftover amoxicillin from a previous prescription.
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