Cancer treatment combines local therapies (surgery, radiation) and systemic therapies (chemotherapy, targeted therapy, immunotherapy, hormone therapy), sometimes followed by hematopoietic stem cell transplantation (HSCT). The goal may be cure, control, or palliation.

Why side effects happen. Conventional chemotherapy kills rapidly dividing cells, so normal tissues with fast turnover are damaged too:

• Bone marrow → neutropenia (infection), thrombocytopenia (bleeding), anemia (fatigue)
• GI mucosa → mucositis, nausea, vomiting, diarrhea
• Hair follicles → alopecia
• Gonads → infertility; many agents harm a fetus

Blood counts fall to their lowest point (nadir) usually 7–14 days after chemotherapy, then recover.

Radiation therapy damages DNA in the treatment field. Side effects are mostly local to the treated area (skin reaction, mucositis in head and neck radiation, diarrhea in pelvic radiation) plus fatigue.

• External beam: the client is not radioactive.
• Sealed internal sources (brachytherapy): the client emits radiation while the source is in place — use time, distance, shielding; private room; no pregnant visitors or visitors under 18 per policy; a dislodged source is picked up with long forceps and placed in the lead container, never by hand. Pregnant staff are not assigned to the client; staff wear a dosimeter badge; limit time at the bedside (per policy, e.g., about 30 minutes per visitor per day), keep about 2 m (6 ft) away when not giving care, and organize care to be done quickly.
• Unsealed sources (e.g., radioactive iodine): body fluids are radioactive for a period; follow radiation safety instructions.

Immunotherapy removes brakes on T cells (immune checkpoint inhibitors) or engineers T cells (CAR T-cell therapy), so its toxicities are immune-mediated rather than marrow-based.

Bone marrow suppression

Headache and vomiting are not caused by marrow suppression itself; they suggest drug effects, intracranial bleeding (with very low platelets), or brain metastasis.

Other findings to assess each visit: oral mucosa (mucositis), nausea and intake, bowel pattern, weight, skin in the radiation field, peripheral neuropathy, fatigue, pain, mood, and signs of immune-related toxicity (diarrhea, cough, rash, fatigue, abnormal thyroid or liver tests).

• CBC with absolute neutrophil count (ANC) = WBC (cells/mm³) × (% segmented neutrophils + % bands) ÷ 100. Example: WBC 2,000/mm³ with 20% segs and 5% bands → 2,000 × 25 ÷ 100 = 500/mm³. ANC < 500/mm³ (0.5 × 10⁹/L) = severe neutropenia
• Kidney and liver function before each cycle (drug clearance and dosing)
• Tumor lysis labs: potassium, phosphate, uric acid, calcium, creatinine
• Echocardiogram (LVEF) before and during anthracyclines and trastuzumab
• Pulmonary function for bleomycin; audiometry for cisplatin when indicated
• Thyroid, liver, glucose, and cortisol tests during checkpoint inhibitor therapy
• Pregnancy test before treatment in people who can become pregnant

Chemotherapy — key drug safety

Nearly all cytotoxic agents are teratogenic — effective contraception during and after treatment as directed.

Targeted therapy

• Trastuzumab (HER2-positive breast cancer): left ventricular dysfunction and heart failure — LVEF before and regularly during therapy; report dyspnea, edema, weight gain; embryo-fetal toxicity
• Bevacizumab: hypertension, bleeding, proteinuria, impaired wound healing, GI perforation — held before and after surgery
• EGFR inhibitors: acne-like rash, diarrhea

Immunotherapy

• Immune checkpoint inhibitors (nivolumab, pembrolizumab, ipilimumab): immune-related adverse events that resemble autoimmune disease — colitis, pneumonitis, hepatitis, dermatitis, thyroiditis, hypophysitis, adrenal insufficiency, new type 1 diabetes. They can start weeks to months after a dose; early reporting matters; treatment is usually corticosteroids and holding the drug
• CAR T-cell therapy: cytokine release syndrome (fever, hypotension, hypoxia) and neurotoxicity

Hormone therapy

• Breast: tamoxifen — hot flashes, venous thromboembolism, endometrial cancer (report vaginal bleeding); aromatase inhibitors — joint pain, bone loss
• Prostate: androgen deprivation (GnRH agonists such as leuprolide, or antagonists) plus androgen receptor blockers — prostate cancer growth depends on testosterone. Effects: hot flashes, loss of libido, bone loss, metabolic changes; GnRH agonists can cause an initial tumor flare

Supportive therapy

• Antiemetics given before chemotherapy on a schedule: 5-HT₃ antagonists (ondansetron — constipation, headache, QT prolongation), NK₁ antagonists (aprepitant), dexamethasone, olanzapine (sedation)
• Myeloid growth factors (filgrastim, pegfilgrastim): shorten neutropenia; bone pain is common; rare splenic rupture (report left upper abdominal or shoulder pain)
• Erythropoiesis-stimulating agents: thrombosis and hypertension risk; used only in specific situations
• Transfusions: irradiated or leukoreduced products per protocol

Cancer pain

• Pain intensity guides the starting drug: mild pain → nonopioid; moderate to severe → opioid, with adjuvants (for neuropathic or bone pain). The classic three-step analgesic ladder is still taught, but a strong opioid can be started directly for severe pain
• Around-the-clock dosing for persistent pain plus rescue doses for breakthrough pain; oral route preferred
• Opioid adverse effects: constipation (tolerance does not develop — start a stimulant laxative with the opioid), nausea (often improves), sedation, and respiratory depression (monitor sedation level; naloxone available). Fear of addiction must not lead to undertreatment

Hematopoietic stem cell transplantation

• Conditioning (high-dose chemotherapy with or without radiation) aims to destroy remaining cancer, suppress the recipient's immunity so the graft is not rejected, and make room in the marrow. It causes profound marrow suppression and infection risk; it does not treat infection
• Complications: infection, bleeding, mucositis, graft-versus-host disease (allogeneic), sinusoidal obstruction syndrome

Listed in priority order.

1. Recognize oncologic emergencies (Section 7). Neutropenic fever — temperature ≥ 38.3 °C (101 °F) once, or ≥ 38.0 °C (100.4 °F) sustained over 1 hour, with ANC < 500/mm³ or expected to fall below 500 — obtain cultures and start IV antibiotics promptly (commonly within 1 hour)
2. Infection prevention
   • Hand hygiene is the most important measure; avoid visitors with infections; no rectal temperatures, suppositories, or enemas
   • Safe food handling (wash produce, cook meat and eggs fully, avoid unpasteurized products); strict "neutropenic diets" have not shown benefit
3. Bleeding precautions (low platelets): soft toothbrush, electric razor, avoid IM injections, aspirin, and NSAIDs; apply pressure after punctures
4. Safe administration
   • Verify orders independently with two qualified nurses; confirm lab values and consent; check blood return before and during vesicant infusion
   • Extravasation: stop the infusion, leave the catheter in place and aspirate, then remove it; do not apply pressure; notify the provider; give the specific antidote per protocol (e.g., dexrazoxane for anthracyclines; hyaluronidase for vinca alkaloids); apply cold (anthracyclines — remove cold packs at least 15 minutes before dexrazoxane) or warm (vinca alkaloids) compresses as directed; elevate and document
   • Hazardous drug handling: chemotherapy-tested double gloves and gown, closed-system transfer devices, spill kit; gloves when handling body fluids for at least 48 hours after chemotherapy (up to 7 days for some drugs, per policy); staff who are pregnant or breastfeeding follow institutional policy on hazardous drug handling
5. Mucositis — soft brush, frequent rinses with saline or saline–bicarbonate, no alcohol-based mouthwash, soft cool bland foods; ice chips during bolus fluorouracil
6. Nutrition and nausea — small frequent meals, cool foods, antiemetics before meals; monitor weight
7. Radiation skin care
   • Wash gently with lukewarm water and mild soap; pat dry; wear loose cotton clothing; do not scratch
   • Avoid heat, ice, tape, and perfumed products on the treated skin; deodorant can usually be continued — follow the radiation team's advice; protect from sun
   • Do not remove skin markings
8. Ostomy care — peristomal redness and erosion are usually from stool leakage: remove the pouch, clean gently with water, dry, protect the skin, and apply a new pouch; remeasure the stoma and cut the wafer opening only about 1/8 inch (2–3 mm) larger than the stoma
9. Psychosocial and fatigue — energy conservation, light exercise as tolerated, body image support (alopecia, ostomy), referral to palliative care for symptom burden

• Take your temperature when you feel unwell; call immediately for 38.0 °C (100.4 °F) or higher — do not take acetaminophen first and wait
• Report bleeding, black stools, shortness of breath, new cough, diarrhea (especially with immunotherapy), mouth sores that stop eating, and swelling or weight gain on trastuzumab
• Take antiemetics as scheduled, not only when nausea is severe; take the laxative with opioids every day
• Use contraception as directed; discuss fertility preservation before treatment
• Avoid live vaccines during treatment unless the oncology team approves; household members can receive most routine vaccines
• Tamoxifen: report calf pain, chest pain, or vaginal bleeding

• Chemotherapy targets rapidly dividing cells: marrow, GI mucosa, hair; nadir about 7–14 days
• Fever in neutropenia is an emergency — antibiotics promptly; hand hygiene is the key prevention
• Doxorubicin and trastuzumab → cardiotoxicity (check LVEF); cisplatin → kidneys and hearing; vincristine → neuropathy and constipation
• Checkpoint inhibitors → immune-related inflammation of any organ; usually treated with corticosteroids
• Opioids → constipation (no tolerance) — scheduled laxative
• Cancer pain: around-the-clock plus breakthrough doses, oral route first, do not undertreat
• Radiation skin: gentle washing, loose cotton clothing, no scratching, no heat or sun
• Brachytherapy: time, distance, shielding; forceps and lead container for a dislodged source
• Vesicant extravasation: stop, leave catheter, aspirate, notify, antidote
• Prostate cancer hormone therapy blocks androgen production or action
• HSCT conditioning destroys cancer, suppresses immunity to prevent rejection, and makes marrow space