Overview
Cancer is a group of diseases in which abnormal cells grow and divide uncontrollably, invade surrounding tissues, and may spread to other parts of the body.
Cancer develops when genetic changes disrupt the normal mechanisms controlling cell growth, division, and death.
Unlike normal cells, cancer cells may:
- Divide when they should not.
- Ignore signals to stop growing.
- Avoid programmed cell death (apoptosis).
- Invade nearby tissues.
- Stimulate the formation of new blood vessels.
- Spread to distant locations.
Cancer can develop in almost any organ or tissue.
Important: Cancer is not a single disease. Different cancers have different causes, behaviors, treatment options, and prognoses.
Benign vs. Malignant Tumors
A tumor (neoplasm) is an abnormal mass of tissue. Tumors can be benign or malignant.
| Characteristic | Benign | Malignant |
|---|---|---|
| Cancerous? | No | Yes |
| Growth | Often slower, though variable | May grow rapidly or slowly |
| Invades nearby tissue? | Does not invade | Can invade |
| Metastasizes? | No | May spread to distant locations |
| Can cause serious problems? | Yes, especially through pressure or obstruction | Yes, through invasion, organ damage, or metastasis |
| Examples | Lipoma, uterine fibroid | Lung carcinoma, osteosarcoma |
Important: A benign tumor can still be dangerous depending on its size and location. Some malignant cancers, such as leukemia, do not typically form solid tumors.
Metastasis
Metastasis is the spread of cancer cells from the original (primary) site to distant tissues or organs.
How Metastasis Occurs
- Cancer cells invade nearby tissues.
- Some cells enter blood vessels or lymphatic vessels.
- The cells travel through the bloodstream or lymphatic system.
- Some leave the vessels and enter distant tissues.
- They may multiply and form secondary tumors.
Common Sites of Metastasis
- Bones: May cause pain or fractures.
- Lungs: May cause coughing or difficulty breathing.
- Liver: May affect liver function and sometimes cause jaundice.
- Brain: May cause headaches, seizures, weakness, or neurological changes.
The sites affected depend on the primary cancer.
Important: Metastatic cancer retains the identity of the original cancer.
For example, breast cancer that spreads to the lungs is called metastatic breast cancer, not primary lung cancer.
Types of Cancer
Cancers can be classified according to the cells or tissues where they originate.
| Type | Tissue of Origin | Examples |
|---|---|---|
| Carcinoma | Epithelial cells lining organs and body surfaces | Lung cancer, many breast cancers, colorectal cancer, prostate cancer |
| Sarcoma | Bone, muscle, fat, cartilage, and other connective tissues | Osteosarcoma, liposarcoma |
| Leukemia | Blood-forming tissue, usually bone marrow | Acute myeloid leukemia, chronic lymphocytic leukemia |
| Lymphoma | Lymphocytes within lymphatic and other tissues | Hodgkin lymphoma, non-Hodgkin lymphoma |
| Central Nervous System (CNS) Cancers | Cells and tissues of the brain or spinal cord | Glioblastoma, medulloblastoma |
| Myeloma | Plasma cells, a type of immune cell | Multiple myeloma |
| Melanoma | Melanocytes, the cells that produce melanin | Cutaneous melanoma |
Important Distinctions
- Carcinoma: Cancer originating in epithelial tissue; the most common broad cancer category.
- Sarcoma: Cancer of connective or supportive tissues.
- Leukemia: Cancer typically involving blood-forming tissue and abnormal blood cells.
- Lymphoma: Cancer originating in lymphocytes.
- CNS Cancers: Cancers originating in the brain or spinal cord; not all brain tumors are malignant.
- Melanoma: Cancer of pigment-producing cells; often occurs in the skin.
Common Cancers
| Cancer | Description | Common Causes / Risk Factors | Possible Signs & Symptoms |
|---|---|---|---|
| Lung Cancer | Cancer arising in lung tissue | Smoking, radon, secondhand smoke, asbestos, air pollution | Persistent cough, coughing blood, chest discomfort, shortness of breath |
| Breast Cancer | Cancer originating in breast tissue | Age, inherited mutations such as BRCA1/2, family history, hormonal factors | Breast lump, skin or nipple changes, abnormal discharge |
| Colorectal Cancer | Cancer of the colon or rectum | Age, family history, hereditary syndromes, smoking, obesity, alcohol | Blood in stool, bowel habit changes, abdominal discomfort, anemia |
| Prostate Cancer | Cancer originating in the prostate | Age, family history, inherited genetic factors | Often asymptomatic early; sometimes urinary symptoms or bone pain if advanced |
| Skin Cancer | Cancer involving skin cells, including basal cell carcinoma, squamous cell carcinoma, and melanoma | UV exposure, prior sunburns, skin characteristics, family history, immune suppression | Changing moles, new or nonhealing skin lesions |
| Pancreatic Cancer | Cancer originating in pancreatic tissue | Smoking, age, chronic pancreatitis, obesity, family history | Jaundice, abdominal or back pain, weight loss |
| Cervical Cancer | Cancer originating in the cervix | Persistent infection with high-risk HPV types | Abnormal vaginal bleeding, unusual discharge, pelvic pain |
| Liver Cancer | Cancer originating in liver tissue | Chronic hepatitis B or C, cirrhosis, alcohol-related liver disease, metabolic dysfunction-associated liver disease | Abdominal pain, weight loss, jaundice |
| Leukemia | Cancer of blood-forming tissues | Risk factors vary; some genetic conditions, prior chemotherapy, radiation exposure | Fatigue, infections, easy bruising, bleeding |
| Lymphoma | Cancer originating in lymphocytes | Risk varies by subtype; immune suppression, some infections, age | Enlarged lymph nodes, night sweats, fever, weight loss |
Important: Many cancers cause few or no symptoms in their early stages. Symptoms alone do not establish a cancer diagnosis.
Causes & Risk Factors
Cancer arises from genetic changes affecting normal cell behavior.
These changes may result from:
- Random errors during cell division.
- Inherited genetic variants.
- Environmental or occupational exposures.
- Certain infections.
- The accumulation of changes over time.
Major Risk Factors
| Risk Factor | How It Contributes | Examples |
|---|---|---|
| Tobacco Use | Exposure to chemicals that damage DNA | Lung, bladder, pancreatic, head and neck cancers |
| Ultraviolet (UV) Radiation | Damages DNA in skin cells | Melanoma, basal cell carcinoma, squamous cell carcinoma |
| Alcohol | Alcohol and its metabolites contribute to cancer risk | Liver, breast, colorectal, esophageal cancers |
| Obesity & Physical Inactivity | Associated with hormonal, inflammatory, and metabolic changes | Colorectal, endometrial, and certain breast cancers |
| Infectious Agents | Certain infections can cause chronic inflammation or directly promote cancer development | HPV, hepatitis B and C, H. pylori |
| Ionizing Radiation | Can damage cellular DNA | Leukemia and certain solid tumors |
| Inherited Genetic Variants | Increase susceptibility to specific cancers | BRCA1/2, Lynch syndrome |
| Age | More time for genetic changes to accumulate | Many cancer types become more common with age |
| Immune Suppression | Reduced immune surveillance can increase risk | Certain lymphomas and infection-associated cancers |
A risk factor increases the likelihood of developing cancer but does not guarantee that cancer will occur.
Carcinogens
A carcinogen is an agent capable of causing cancer.
Carcinogens may be chemical, physical, or biological.
| Category | Examples |
|---|---|
| Chemical | Tobacco smoke, asbestos, benzene |
| Physical | Ultraviolet radiation, ionizing radiation |
| Biological | High-risk HPV, hepatitis B and C viruses, Helicobacter pylori |
Important: Carcinogen exposure does not guarantee cancer. Risk depends on the agent, exposure, duration, and individual susceptibility.
Cancer Prevention
Measures that can reduce the risk of certain cancers include:
- Avoiding tobacco and secondhand smoke.
- Limiting alcohol consumption.
- Protecting skin from excessive UV exposure.
- Maintaining regular physical activity.
- Following a healthy dietary pattern.
- Receiving recommended HPV and hepatitis B vaccinations.
- Reducing avoidable occupational carcinogen exposure.
- Participating in age- and risk-appropriate cancer screening.
Cancer cannot always be prevented, and having cancer does not imply that someone made unhealthy choices.
How Cancer Is Diagnosed
Cancer diagnosis often involves a combination of clinical evaluation, laboratory testing, imaging, and tissue examination.
| Method | Purpose |
|---|---|
| Medical History & Physical Examination | Identify symptoms, findings, and risk factors |
| Screening Tests | Detect possible cancer or precancerous changes before symptoms develop |
| Blood & Laboratory Tests | Identify abnormalities or measure selected biomarkers |
| Imaging (CT, MRI, Ultrasound, PET) | Locate abnormalities and assess their extent |
| Endoscopy | Examine internal organs and potentially obtain tissue samples |
| Biopsy | Remove cells or tissue for microscopic examination |
| Pathology | Identify cancer type, cellular features, and other characteristics |
| Molecular / Biomarker Testing | Identify tumor characteristics that may guide treatment |
Biopsy
A biopsy removes a tissue or cell sample for examination.
A pathologist examines the sample to determine whether cancer is present and may identify the type and grade.
A biopsy is often needed for a definitive diagnosis, although some cancers can be diagnosed through specialized blood or bone marrow testing.
Screening vs. Diagnosis
- Screening: Tests people without symptoms to look for possible disease.
- Diagnostic Testing: Investigates symptoms or abnormal screening results to establish a diagnosis.
A positive screening result does not automatically mean cancer is present.
Staging Cancer
Cancer staging describes the extent of cancer within the body, including tumor size, involvement of nearby structures or lymph nodes, and distant spread.
Staging helps determine treatment options and estimate prognosis.
TNM Staging System
The TNM system is used for many solid tumors.
- T — Tumor: Size or local extent of the primary tumor.
- N — Nodes: Whether nearby regional lymph nodes contain cancer.
- M — Metastasis: Whether cancer has spread to distant sites.
General Cancer Stages
| Stage | General Meaning |
|---|---|
| Stage 0 | Carcinoma in situ: abnormal cells have not invaded nearby tissue |
| Stage I | Often a relatively small or localized cancer |
| Stage II | More extensive local disease, depending on cancer type |
| Stage III | More advanced local or regional disease, often involving nearby nodes |
| Stage IV | Distant metastatic spread for many solid cancers |
Important: These descriptions are general. Staging differs by cancer type; leukemia, lymphoma, and many CNS tumors use other classification or staging approaches.
Stage vs. Grade
- Stage: How far the cancer has spread.
- Grade: How abnormal the cancer cells appear and, in some cancers, how aggressively they may behave.
Stage describes extent; grade describes cellular characteristics.
Treatment Options
Cancer treatment depends on cancer type, stage, molecular characteristics, overall health, and the patient’s goals.
| Treatment | How It Works |
|---|---|
| Surgery | Removes cancerous tissue; may also relieve symptoms |
| Chemotherapy | Uses drugs to kill or inhibit cancer cells, often affecting other rapidly dividing cells |
| Radiation Therapy | Uses high-energy radiation to damage or destroy cancer cells |
| Immunotherapy | Helps the immune system recognize or attack cancer |
| Targeted Therapy | Targets specific molecules or pathways involved in cancer growth |
| Hormone Therapy | Reduces or blocks hormones that support certain cancers |
| Stem Cell Transplant | Restores blood-forming cells after certain intensive treatments |
| Active Surveillance | Carefully monitors selected cancers without immediate treatment |
| Palliative Treatments | Relieve symptoms or complications, sometimes alongside cancer-directed treatment |
Treatment may combine several approaches.
Treatment Goals
- Curative: Attempt to eliminate the cancer.
- Disease Control: Slow progression or maintain remission.
- Palliative: Relieve symptoms and improve quality of life.
Not every cancer is curable, but even incurable cancers may be treatable.
Common Effects of Cancer & Treatment
Both cancer and its treatments can cause symptoms.
| Effect | Possible Causes |
|---|---|
| Fatigue | Cancer, anemia, treatment, sleep disruption, poor nutrition |
| Pain | Tumor pressure or invasion, procedures, treatment effects |
| Nausea & Vomiting | Chemotherapy, medications, cancer-related illness |
| Loss of Appetite / Weight Loss | Cancer-related metabolic changes, nausea, taste changes, swallowing problems |
| Hair Loss (Alopecia) | Certain chemotherapy regimens and radiation to hair-bearing areas |
| Mucositis / Mouth Sores | Certain chemotherapy and radiation treatments |
| Diarrhea or Constipation | Treatments, medications, altered intake, disease |
| Peripheral Neuropathy | Certain chemotherapy medications or tumor-related nerve injury |
| Anemia | Cancer, bleeding, impaired bone marrow function, treatment |
| Neutropenia | Reduced neutrophils, sometimes caused by chemotherapy, increasing infection risk |
| Thrombocytopenia | Reduced platelets, increasing bruising and bleeding risk |
| Skin Changes | Radiation, medications, surgery, underlying disease |
| Emotional Distress | Uncertainty, symptoms, treatment burden, changes in independence |
These effects vary considerably. Not every person with cancer experiences the same symptoms.
Palliative Care
Palliative care is specialized care focused on relieving symptoms, reducing suffering, and improving quality of life for people living with serious illness.
It can address:
- Pain.
- Fatigue.
- Nausea and other physical symptoms.
- Emotional distress.
- Social and spiritual concerns.
- Treatment decisions and goals of care.
Palliative care can begin at diagnosis and can be provided alongside treatments intended to cure or control cancer.
Palliative Care vs. Hospice
- Palliative Care: Can be provided at any stage of serious illness, including during curative treatment.
- Hospice Care: Focuses on comfort and quality of life when care goals have shifted away from curing the terminal illness.
See Caring for Residents with Cancer.
CNA Considerations
- Observe and report new symptoms or changes from baseline.
- Follow prescribed infection-prevention precautions.
- Report fever or signs of infection promptly, especially in residents receiving chemotherapy.
- Observe fatigue, pain, food and fluid intake, nausea, bowel changes, and skin integrity.
- Support permitted activity and independence.
- Follow individualized mobility, nutritional, and treatment-related precautions.
- Protect confidentiality and respect the resident’s care preferences.
- Do not independently diagnose cancer, interpret staging, or provide cancer-specific treatment.
When to Report
- New or worsening pain.
- Fever, chills, or signs of infection.
- Unexpected bruising or bleeding.
- Significant fatigue or weakness.
- Persistent nausea, vomiting, or diarrhea.
- Poor intake, dehydration, or rapid weight loss.
- New confusion or functional decline.
- New difficulty breathing or swallowing.
- Changes around surgical wounds or treatment sites.
Emergency signs: Severe breathing difficulty, uncontrolled bleeding, sudden neurological changes, or unresponsiveness require immediate emergency response.
A fever in a patient with known or suspected neutropenia may represent a medical emergency and requires immediate clinical assessment.
Study Notes
Clinical Connections
- Caring for Residents with Cancer: Symptom support, person-centered care, and palliative care.
- Standard Precautions: Some treatments weaken immune defenses.
- Recognizing Patient Distress: Cancer and treatment complications may require urgent attention.
- Skin Integrity & Breakdown Prevention: Immobility, malnutrition, and treatment effects can increase skin vulnerability.
- Fluid Balance: Vomiting, diarrhea, or poor intake can disturb hydration.
- Vital Signs: Fever and other abnormalities may indicate illness or complications.
Questions
- What is cancer?
- How do benign and malignant tumors differ?
- What is metastasis?
- What distinguishes carcinoma, sarcoma, leukemia, and lymphoma?
- What are carcinogens?
- How do tobacco, UV radiation, and certain infections contribute to cancer risk?
- What is the difference between screening and diagnosis?
- Why is a biopsy important?
- How do cancer stage and grade differ?
- What do T, N, and M represent?
- What are the major treatment options?
- What complications can result from chemotherapy?
- How does palliative care differ from hospice?
Sources
- National Cancer Institute — What Is Cancer?
- National Cancer Institute — Risk Factors for Cancer
- National Cancer Institute — How Cancer Is Diagnosed
- National Cancer Institute — Cancer Staging
- National Cancer Institute — Types of Cancer Treatment
- National Cancer Institute — Treatment Side Effects
- National Cancer Institute — Palliative Care in Cancer
Flashcards
What is cancer?01-foundations / diseases-conditions
Uncontrolled growth of abnormal cells that can invade tissues and spread.
What is the difference between benign and malignant tumors?02-mechanisms / diseases-conditions
Benign tumors do not invade or metastasize; malignant tumors can.
What is metastasis?01-foundations / diseases-conditions
Spread of cancer from its primary site to distant tissues or organs.
If breast cancer spreads to the lungs, what is it called?01-foundations / diseases-conditions
Metastatic breast cancer.
What is a carcinoma?01-foundations / diseases-conditions
Cancer originating in epithelial tissue.
What is a sarcoma?01-foundations / diseases-conditions
Cancer originating in bone or connective and supportive tissues.
What is leukemia?01-foundations / diseases-conditions
Cancer generally originating in blood-forming tissue, often the bone marrow.
What is lymphoma?01-foundations / diseases-conditions
Cancer originating in lymphocytes.
What are CNS cancers?01-foundations / diseases-conditions
Malignancies originating in brain or spinal cord tissues.
What is a carcinogen?01-foundations / diseases-conditions
An agent capable of causing cancer.
What infections are associated with liver cancer?02-mechanisms / diseases-conditions
Chronic hepatitis B and hepatitis C infections.
What infection is strongly associated with cervical cancer?02-mechanisms / diseases-conditions
Persistent high-risk human papillomavirus (HPV) infection.
What is the difference between cancer screening and diagnosis?02-mechanisms / diseases-conditions
Screening looks for possible disease; diagnostic testing investigates or confirms it.
What is a biopsy?01-foundations / diseases-conditions
Removal of cells or tissue for diagnostic examination.
What does TNM stand for in cancer staging?02-mechanisms / diseases-conditions
Tumor, Nodes, Metastasis.
What does Stage IV generally mean for many solid cancers?02-mechanisms / diseases-conditions
Cancer has spread to distant parts of the body.
What is the difference between cancer stage and grade?02-mechanisms / diseases-conditions
Stage describes extent; grade describes cellular characteristics.
What is chemotherapy?01-foundations / diseases-conditions
Drug treatment that kills or inhibits cancer cells.
What is immunotherapy?01-foundations / diseases-conditions
Treatment that helps the immune system fight cancer.
What is neutropenia?01-foundations / diseases-conditions
An abnormally low neutrophil count, increasing infection risk.
What is palliative care?01-foundations / diseases-conditions
Care focused on symptom relief, comfort, and quality of life.
Can palliative care be provided alongside curative cancer treatment?01-foundations / diseases-conditions
Yes. Palliative care can begin at diagnosis and continue during treatment.