Cancer Basics
Uncontrolled cell growth — and why spread is what matters.
Cancer is the uncontrolled, abnormal growth of cells. Whether a tumor is dangerous depends largely on whether it can spread.
- GrowthBenign
- Slow, often encapsulated
- GrowthMalignant (cancer)
- Rapid, invades nearby tissue
- SpreadBenign
- Does NOT spread
- SpreadMalignant
- Metastasizes via blood & lymph
- DangerBenign
- Usually not life-threatening
- DangerMalignant
- Can be life-threatening
- Metastasis = spread to distant sites; it is what makes cancer deadly.
- Staging describes how far the cancer has spread (the TNM system: Tumor size, Nodes, Metastasis).
- Grading describes how abnormal the cells look under a microscope.
Most oncology nursing comes down to two things: protecting the client from the side effects of treatment (especially infection and bleeding from bone marrow suppression) and recognizing oncologic emergencies early. Keep those two themes in mind and the details fall into place.
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Warning Signs & Prevention
The classic CAUTION warning signs.
The American Cancer Society's warning signs use the mnemonic CAUTION:
- C — Change in bowel or bladder habits
- A — A sore that does not heal
- U — Unusual bleeding or discharge
- T — Thickening or a lump
- I — Indigestion or difficulty swallowing
- O — Obvious change in a wart or mole
- N — Nagging cough or hoarseness
Major modifiable risks include tobacco, excess sun, poor diet, obesity, and certain viruses (HPV, hepatitis B). Screening catches cancer early: mammograms, colonoscopy, Pap smears, and skin checks. Teaching prevention and screening is a core nursing role.
Treatment Modalities
Often used in combination.
- Surgery
- Removes the tumor (local)
- Chemotherapy
- Systemic drugs that kill rapidly dividing cells
- Radiation
- Targeted high-energy beams or implants (local)
- Immunotherapy / targeted therapy
- Helps the immune system or targets specific cancer features
- Hormonal therapy
- Blocks hormones that fuel some cancers (breast, prostate)
- Stem cell / bone marrow transplant
- Replaces marrow after high-dose treatment
Chemotherapy
Powerful, systemic — and it hits healthy fast-growing cells too.
Chemotherapy kills rapidly dividing cells. The problem is that some healthy cells also divide quickly — the bone marrow, GI lining, and hair follicles — so that's where the side effects show up.
Common Side Effects
- Bone marrow suppression (myelosuppression) — the most dangerous (see next section)
- Nausea & vomiting — give antiemetics before chemo
- Mucositis / stomatitis — painful mouth sores
- Alopecia — hair loss (usually temporary)
- Fatigue and diarrhea
Chemotherapy agents are toxic to anyone exposed. Nurses handle them with chemo precautions — gowns, double gloves, and special disposal — and body fluids may be considered hazardous for ~48 hours after a dose. This protects staff and family.
Bone Marrow Suppression
The most dangerous chemo effect — three cell lines drop.
- Neutrophils ↓neutropenia
- Can't fight infection → neutropenic precautions; fever = emergency
- Platelets ↓thrombocytopenia
- Bleeding risk → bleeding precautions
- Red cells ↓anemia
- Fatigue, pallor, SOB → rest, energy conservation
Counts are usually lowest about 7–14 days after treatment (the nadir).
Neutropenic precautions: private room, strict hand hygiene, no fresh flowers/plants or raw fruits/vegetables, screen visitors, avoid invasive procedures. A temperature of 100.4°F (38°C) or higher may be the only sign of a life-threatening infection — report it immediately. For thrombocytopenia: soft toothbrush, electric razor, no IM injections/rectal temps, and avoid aspirin/NSAIDs.
? A chemo patient develops a temperature of 100.6°F. What is your priority action?
Radiation Therapy
External (client is safe) vs internal (client is a source).
- SourceExternal beam
- Machine outside the body
- SourceInternal (brachytherapy)
- Radioactive implant inside/on the body
- Is the client radioactive?External beam
- No — safe to be near
- Is the client radioactive?Brachytherapy
- Yes — temporarily a radiation source
Radiation Safety (for internal radiation)
- Time — limit time spent near the client
- Distance — stay as far away as practical
- Shielding — use lead shielding; keep the client in a private room
- Keep pregnant nurses, pregnant visitors, and children away; keep long-handled forceps and a lead container in the room in case an implant dislodges.
Treat the irradiated skin gently: do not wash off the markings, use mild soap and water, pat dry, avoid lotions/powders/deodorant on the site unless prescribed, and protect the area from sun and heat/cold. The skin in the treatment field is fragile.
Oncologic Emergencies
Know these — they're heavily tested.
- Tumor lysis syndrome
- Rapid cell death → ↑K⁺, ↑phosphate, ↑uric acid, ↓Ca²⁺ → kidney failure/arrhythmias. Tx: IV hydration, allopurinol
- Febrile neutropenia
- Fever in a neutropenic client → treat as sepsis immediately
- Superior vena cava syndrome
- Tumor compresses the SVC → facial/arm swelling, distended neck veins, dyspnea
- Spinal cord compression
- Tumor presses the cord → back pain, weakness, numbness, bowel/bladder changes
- Hypercalcemia
- From bone metastasis → confusion, weakness, arrhythmias
When chemo kills many cells fast, their contents flood the blood. The dangerous combination is high potassium (arrhythmias) and high uric acid/phosphate (kidney failure). Prevention is key: lots of IV fluids and allopurinol before and during treatment, with close monitoring of electrolytes and kidney function.
Nursing Care & Symptom Management
Comfort, protection, and support through treatment.
- Nausea/vomiting — antiemetics scheduled before chemo; small, bland meals.
- Mucositis — gentle oral care with a soft brush and saline rinses; avoid spicy, acidic, or rough foods and alcohol-based mouthwash.
- Nutrition — high-calorie, high-protein; manage taste changes.
- Pain — treat around the clock; opioids are appropriate for cancer pain.
- Fatigue — balance rest and activity.
- Psychosocial — support body-image changes (alopecia), fear, and grief.
Across all of oncology nursing, preventing and catching infection early is the highest priority, because the immune system is weakened by both the cancer and the treatment. Hand hygiene, neutropenic precautions, and prompt fever response save lives.
Key Medications
Supportive drugs you'll see in oncology.
- Ondansetron (and other antiemetics)
- Prevent chemo nausea/vomiting (give before chemo)
- Filgrastim (G-CSF)
- Stimulates white blood cell production in neutropenia
- Epoetin alfa
- Stimulates red cell production for anemia
- Allopurinol
- Lowers uric acid to prevent tumor lysis syndrome
- Opioids
- Cancer pain control (around the clock)
- Chemotherapy agents
- Alkylating agents, antimetabolites, and others — handled as hazardous drugs
Anchor on the logic: cancer is uncontrolled growth that spreads; treatments kill fast-dividing cells (so they hit marrow, gut, and hair); the biggest dangers are infection, bleeding, and oncologic emergencies; and internal radiation makes the client a temporary source (time, distance, shielding). The cheatsheet condenses it all.
Frequently Asked Questions
Common student questions on this topic.
What is the difference between a benign and a malignant tumor?
Why do chemotherapy clients need neutropenic precautions?
What is the difference between external and internal radiation therapy?
What are the main side effects of chemotherapy?
What is tumor lysis syndrome?
What are the warning signs of cancer (CAUTION)?
Quick-Reference Cheatsheet
Every key point from this guide on a single printable page.
Oncology & Cancer Care Cheatsheet
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