MEDREH · EP 03 · CANCER
Before You Listen
Episode Setup
- Topic in one line: the counterintuitive Grade A evidence that exercise (not rest) is the most effective treatment for cancer-related fatigue (CRF), the platelet, hemoglobin, and absolute neutrophil count (ANC) thresholds that modify chemotherapy exercise prescription, the upper-trunk versus lower-trunk distinction between radiation plexopathy (myokymic discharges on EMG) and tumor plexopathy (painful, Horner syndrome with Pancoast tumor), four-component complete decongestive therapy (CDT) for lymphedema, Mirels classification for pathologic fracture risk (≥9 surgery, ≤7 radiation), dexamethasone-first management of malignant spinal cord compression, chemotherapy-induced peripheral neuropathy (CIPN) by drug class (taxanes, vinca, platinums with coasting, bortezomib), Lambert-Eaton myasthenic syndrome (LEMS) and other paraneoplastic syndromes, anthracycline cardiomyopathy, bleomycin pulmonary fibrosis, steroid myopathy, late radiation effects, hematopoietic stem cell transplant (HSCT) deconditioning and graft-versus-host disease (GVHD), and the four-tier Dietz continuum.
- Prerequisites: chemotherapy mechanism categories, brachial plexus anatomy from upper trunk (C5-C6) to lower trunk (C8-T1), lymphatic drainage of the upper extremity through the axilla, the dorsal root ganglion as the cell body for sensory neurons, and the neuromuscular junction with presynaptic voltage-gated calcium channels and postsynaptic acetylcholine receptors.
- Runtime: 1 hour 5 minutes.
Vignette. A 58-year-old woman with stage IIB right-sided breast cancer completed adjuvant chemotherapy with doxorubicin and paclitaxel followed by axillary lymph node dissection and right-sided chest wall radiation 18 months ago. She presents with progressive right upper extremity weakness over 4 months, mild paresthesias in the C5-C6 distribution, and visible undulating skin movements over her right shoulder. She denies pain. Examination shows 4-/5 right deltoid and biceps strength, decreased sensation over the lateral arm, and 3+ pitting edema of the right arm with non-pitting fibrotic changes at the proximal forearm. Magnetic resonance imaging of the brachial plexus shows diffuse thickening and enhancement of the upper trunk without a discrete mass. Electromyography shows myokymic discharges in C5-C6 innervated muscles. She also reports overwhelming fatigue, sleeps 14 hours daily, and has stopped exercising because “it makes me more tired.”
What is the diagnosis of her plexopathy and what specific EMG finding clinches it, what is the lymphedema stage and the four components of the gold-standard treatment, what evidence-based intervention should be prescribed for her cancer-related fatigue, and what late cardiac and pulmonary surveillance is indicated given her chemotherapy regimen?
(Answer at the end of this chapter)
Section 1: Cancer-Related Fatigue and Lab-Value Exercise Precautions
Bottom line: cancer-related fatigue (CRF) affects 60-90 percent of patients during and after treatment and is unrelieved by rest; Grade A evidence supports moderate aerobic exercise (3-5 days per week, 20-30 minutes per session) as the most effective treatment, during and after active treatment. Lab thresholds modify the prescription: platelets < 50,000/microliter restrict high-impact and contact activities, < 20,000/microliter limit exercise to gentle range of motion and light ambulation, hemoglobin < 8 g/dL reduces tolerable intensity, and absolute neutrophil count (ANC) < 500/microliter avoids public gyms and pools. The Dietz continuum has four tiers: preventive (prehabilitation), restorative, supportive, and palliative. Prehabilitation before surgery or chemotherapy improves postoperative recovery, reduces complications, and shortens length of stay.
Cancer-related fatigue is the single most common symptom in cancer patients, affecting 60-90 percent during and after treatment. It is qualitatively distinct from normal fatigue: overwhelming, persistent, disproportionate to activity, and not relieved by rest. Etiology is multifactorial (anemia, deconditioning, depression, sleep disruption, pain, cytokines, medications, nutrition). The single most important board fact is that exercise is the most effective intervention for CRF, supported by Grade A evidence. Patients reflexively assume they should rest more; the evidence is exactly the opposite. Moderate aerobic exercise 3-5 days per week for 20-30 minutes per session reduces CRF, improves physical function, lifts mood, and improves quality of life, both during active treatment and during survivorship.
Lab-value exercise precautions during chemotherapy reflect myelosuppression from cytotoxic agents. The board tests specific thresholds.
Platelet count. Less than 50,000/microliter triggers avoidance of high-impact activities, contact sports, heavy resistance training, and fall-risk activities. Less than 20,000/microliter limits the patient to gentle range of motion and light ambulation; active bleeding is a contraindication to exercise.
Hemoglobin. Less than 8 g/dL mandates reduced exercise intensity. Light aerobic activity may still be tolerated. Symptoms during exercise (tachycardia, dyspnea, dizziness, presyncope) are stop signals.
Absolute neutrophil count (ANC). Less than 500/microliter is severe immunocompromise. Avoid public gyms, swimming pools, and any setting with increased microbial exposure. A clean home environment is acceptable. Any sign of infection requires immediate medical evaluation because febrile neutropenia is a medical emergency.
Bone metastases restrict high-impact activity at involved sites; the Mirels classification (Section 3) governs specific precautions.
Mnemonic — “50K bleeds, 20K rests, 8 oxygens, 500 isolates”
Platelets 50 thousand: stop the bleeding-risk sports. Platelets 20 thousand: rest, range of motion only. Hemoglobin 8: reduce intensity, oxygen delivery is the limit. ANC 500: isolate from public gyms because immune system cannot defend against infection. Four numbers map to four myelosuppression actions.
The cancer rehabilitation continuum (Dietz) has four tiers. Preventive (prehabilitation) intervenes before treatment to optimize baseline function. Restorative aims to return the patient to baseline after treatment. Supportive maintains function during chronic or progressive disease. Palliative focuses on comfort and meaningful function in advanced disease.
Prehabilitation before major cancer surgery or chemotherapy has growing Grade A evidence: improved postoperative recovery, reduced complications, shorter length of stay, and improved functional status at 6-12 weeks post-treatment. The trimodal program combines structured exercise (aerobic plus resistance), nutritional optimization (protein 1.2-1.5 g/kg/day), and psychological support, intensively front-loaded into the typical 2-6 week window.
High Yield — CRF, lab thresholds, rehab continuum
- CRF: 60-90 percent prevalence; exercise is Grade A treatment (moderate aerobic 3-5x/wk, 20-30 min); not rest.
- Platelets < 50K: avoid high-impact, contact, fall-risk; < 20K: gentle ROM and light ambulation only.
- Hemoglobin < 8: reduce intensity; watch for tachycardia, dyspnea, dizziness.
- ANC < 500: avoid public gyms/pools/crowded facilities; private clean environment OK; fever = emergency.
- Cancer rehab continuum (Dietz): Preventive → Restorative → Supportive → Palliative.
- Prehabilitation: trimodal (exercise + nutrition + psychological) before treatment improves outcomes.