NLE Oncology Nursing — Cancer Pathophysiology, Prevention and DetectionSummary

Cancer develops through three sequential phases: (1) **Initiation**—a carcinogen (chemical, physical, infectious, or genetic agent) causes irreversible DNA mutation in a single cell. This mutation alone does not cause cancer but primes the cell. (2) **Promotion**—repeated exposure to promoting agents (tobacco, alcohol, hormones, chronic inflammation, or dietary factors) stimulates the mutated cell to proliferate. Critically, this stage is *reversible*, making it the window where prevention has maximum impact. (3) **Progression**—the tumor grows, develops its own blood supply through angiogenesis, becomes increasingly malignant, invades surrounding tissue, and gains the ability to metastasize. This evolution typically occurs over months to years, not overnight. Understanding this allows nurses to counsel on modifiable factors (smoking cessation, alcohol reduction, sun protection) that interrupt progression, especially during the reversible promotion phase.

At the cellular level, two gene families control cancer risk. **Proto-oncogenes** are normal genes that promote healthy cell growth and differentiation. When mutated into **oncogenes**, they become permanently 'turned on,' driving relentless, unregulated cell proliferation (imagine an accelerator pedal stuck to the floor). Examples include RAS and MYC. **Tumor suppressor genes** (such as **p53**, the 'guardian of the genome,' and RB) normally apply brakes to cell division and activate apoptosis (programmed cell death) when cells are damaged or old. When lost or inactivated, these brakes fail. A cell becoming cancerous typically requires *both* activated oncogenes *and* loss of tumor suppressor function—a 'double hit.' This is why cancer often takes years and multiple exposures to develop; multiple mutations must accumulate.

Normal cells exhibit two key safety mechanisms. **Contact inhibition** means that when a cell touches a neighboring cell, it stops dividing—the tissue forms an organized, controlled layer (like a single layer of bricks in a wall). Cancer cells ignore this signal and pile up on one another, forming thick, disorganized masses. **Apoptosis** is programmed cell death; normal cells activate it when they are old, damaged, or no longer needed. This is *healthy* death—a form of cellular housekeeping. Cancer cells evade apoptosis, so damaged and mutated cells survive when they should die. Together, loss of contact inhibition and failure of apoptosis explain why cancer cells grow in an uncontrolled, chaotic manner, piling up into tumors.

**Metastasis** is the spread of cancer from the primary (original) site to distant organs—the hallmark of malignant disease and the primary reason cancer is life-threatening. Spread occurs by four routes: (1) **Direct extension**—cancer invades through the capsule into surrounding tissue, then into blood and lymphatic vessels; (2) **Lymphatic spread**—the *most common route for carcinomas*, cancer cells enter lymphatic vessels and lodge in regional lymph nodes (hence the N classification in TNM staging); (3) **Hematogenous (bloodstream) spread**—cells enter blood vessels and travel to distant organs; (4) **Transcoelomic seeding**—cells cross body cavities (e.g., cancer cells shed into the peritoneal cavity). **Common metastatic sites** are the **lungs** (first-line filter for blood-borne cells), **liver** (second filter), **bone** (rich blood supply, common for breast and prostate cancer), and **brain** (especially for lung cancer). Critically, a metastatic tumor retains the cell type of its origin—breast cancer metastatic to bone is still breast cancer histologically, not bone cancer. This principle guides treatment and prognosis.

Nurses must distinguish benign from malignant growths using seven key criteria: (1) **Growth rate**: Benign tumors grow slowly, sometimes not at all; malignant tumors grow rapidly and relentlessly. (2) **Cell differentiation**: Benign cells are well differentiated—they closely resemble the normal tissue of origin (e.g., a lipoma looks like fat cells). Malignant cells are poorly differentiated or anaplastic, bearing little resemblance to normal cells. (3) **Encapsulation**: Benign tumors are usually encapsulated—surrounded by a fibrous capsule that contains them. Malignant tumors are not encapsulated; they infiltrate and invade surrounding tissue. (4) **Metastasis**: Benign tumors do *not* metastasize. Malignant tumors *metastasize* to distant sites. (5) **Recurrence**: Benign tumors rarely recur after removal; malignant tumors frequently recur if not completely treated. (6) **Effect on the host**: Benign tumors are usually harmless unless they press on a vital structure (e.g., a benign brain tumor can be dangerous if it compresses the brainstem). Malignant tumors are inherently life-threatening. (7) **Naming convention**: Benign tumors end in **-oma** (lipoma, fibroma, adenoma); malignant tumors are **carcinomas** (from epithelial tissue, e.g., lung carcinoma), **sarcomas** (from connective tissue, muscle, or bone, e.g., osteosarcoma), **leukemias** (blood-forming tissue), or **lymphomas** (lymphoid tissue). This table is a *must-memorize* for the NLE.

The American Cancer Society's **CAUTION** mnemonic teaches the seven persistent warning signs that warrant immediate medical evaluation. **C**—**Change in bowel or bladder habits** (new constipation, diarrhea, urgency, frequency, or inability to void; blood in stool or urine). **A**—**A sore that does not heal**, especially on the skin, lips, or in the mouth; a non-healing wound is suspicious for malignancy. **U**—**Unusual bleeding or discharge** from any body opening (vaginal bleeding between periods, blood in sputum or vomit, blood in stool, unexplained bruising). **T**—**Thickening or a lump in the breast or elsewhere**, including skin nodules, abdominal masses, or enlarged lymph nodes. **I**—**Indigestion or difficulty swallowing** (dysphagia); persistent epigastric discomfort; dysphagia can signal esophageal or stomach cancer. **O**—**Obvious change in a wart or mole**—growth, color change, itching, bleeding, asymmetry (related to the ABCDE rule for melanoma). **N**—**Nagging cough or hoarseness** lasting more than a few weeks; suggests lung, laryngeal, or throat cancer. The key word is **persistent**—these symptoms lasting weeks warrant investigation, though not all are cancer. This mnemonic is *repeatedly tested* on the NLE and is essential patient education content.

**Grading** is assigned by a pathologist examining tumor cells under a microscope and assesses how closely the cancer cells resemble normal, healthy tissue of the same type—their degree of **differentiation**. **Grade 1 (Well differentiated)**: Cancer cells closely resemble normal tissue; tumor grows slowly; most favorable prognosis. **Grade 2 (Moderately differentiated)**: Cancer cells somewhat abnormal; intermediate growth and behavior. **Grade 3 (Poorly differentiated)**: Cancer cells look quite abnormal; aggressive growth. **Grade 4 (Undifferentiated/Anaplastic)**: Cancer cells bear little to no resemblance to normal tissue; highly aggressive, rapid growth; poorest prognosis. Higher grade = more aggressive and more likely to metastasize quickly. Grading is determined by **histology** (tissue examination) and is independent of size or spread; a small grade 4 tumor is more dangerous than a large grade 1 tumor. For example, breast cancer grades range from 1 to 3, and a grade 3 breast cancer is more aggressive than grade 1, regardless of tumor size.

The **TNM system** is the international standard for staging solid tumors and integrates three parameters: (1) **T (Tumor)**: Size and local extent of the primary tumor. **Tis** = carcinoma in situ (cancer confined to the epithelial layer of origin, not invading deeper layers; early, potentially curable). **T1–T4** indicate increasing tumor size and/or local invasion into adjacent structures (T1 smallest, T4 largest/most invasive). (2) **N (Nodes)**: Extent of regional lymph node involvement. **N0** = no regional lymph node involvement (best); **N1–N3** indicate progressive involvement of more nodes or more distant nodes (N3 most extensive). (3) **M (Metastasis)**: Presence of distant metastasis. **M0** = no distant metastasis (best); **M1** = distant metastasis present (worst). These combine into an **overall stage**: **Stage 0** = Tis, N0, M0 (in situ, highly curable); **Stage I–III** = increasing local and nodal involvement but no distant metastasis; **Stage IV** = M1 (distant metastasis; most advanced, generally incurable but treatable for prolonged survival). Example: A patient with breast cancer described as T2, N1, M0 has a Stage II tumor—moderate size, some lymph node involvement, but no distant spread. This staging guides treatment intensity and helps predict prognosis. A patient with T4, N3, M1 disease (Stage IV) has the worst prognosis and usually receives palliative rather than curative treatment.

**Biopsy** is the definitive diagnostic test for cancer—it is the only way to confirm malignancy histologically. Biopsy types include: **Needle biopsy** (fine-needle aspiration or core needle biopsy—minimally invasive); **incisional biopsy** (removal of a sample of the tumor); **excisional biopsy** (removal of the entire lesion, often done for accessible tumors like skin lesions or breast lumps). The pathologist examines the tissue to identify the cancer type and assign grade. **Supporting diagnostic studies** include: **Imaging** (X-ray, CT, MRI, ultrasound, PET scan) to assess local extent and detect metastasis; **Endoscopy** (colonoscopy, bronchoscopy, esophagogastroduodenoscopy) for cancers of hollow organs; **Tumor markers** (blood tests measuring substances produced by cancer cells: PSA for prostate, CA-125 for ovarian, CEA for colorectal, AFP for liver/testicular). Critically, tumor markers are **not used to diagnose cancer** (they lack specificity—benign conditions can raise them) but are used to **monitor treatment response** and **detect recurrence**. A rising tumor marker after treatment may signal recurrence before imaging shows it. Definitive diagnosis requires histology from biopsy; no blood test alone diagnoses cancer.

**Primary prevention** aims to eliminate or reduce exposure to carcinogens so cancer never develops. It is the most cost-effective cancer control strategy and is reversible during the **promotion phase** of carcinogenesis. Key nursing interventions: (1) **Tobacco cessation**—smoking is the single most modifiable risk factor linked to lung, oral, esophageal, bladder, and other cancers. Counsel all patients, provide cessation resources, and address secondhand smoke exposure. (2) **Alcohol reduction**—excessive alcohol increases risk of breast, liver, colorectal, and esophageal cancers. (3) **Sun protection**—counsel sunscreen (SPF 30+), protective clothing, and avoidance of peak UV hours (10 am–4 pm) to prevent melanoma and non-melanoma skin cancers. (4) **Healthy diet and weight**—promote fiber (30g/day), fruits, vegetables, whole grains; limit fat, salt-cured/smoked/processed foods (preserved meats like tocino and longganisa linked to colorectal cancer), sugar-sweetened beverages, and ultra-processed foods. Maintain healthy weight (BMI 18.5–24.9) and physical activity (150 min/week moderate intensity). (5) **Vaccination**—the **HPV vaccine** (Gardasil, Cervarix) prevents cervical, anal, oropharyngeal, and other HPV-related cancers; recommended ages 9–45, with best outcomes if given before sexual activity. The **hepatitis B vaccine** prevents liver cancer by preventing chronic HBV infection; recommended for all children and at-risk adults. (6) **Occupational/environmental safety**—minimize exposure to asbestos (mesothelioma), benzene (leukemia), and radiation. In the Filipino context, emphasize HPV vaccination (cervical cancer is common and preventable), hepatitis B vaccination (endemic in Philippines), and smoking/sun protection.

**Secondary prevention** detects cancer early, before symptoms appear, when it is most curable and treatment less invasive. Screening is population-based; it targets asymptomatic individuals at risk. Key screening modalities: (1) **Breast cancer**—monthly **breast self-examination (BSE)** (teach women to inspect and palpate breasts for lumps, dimpling, discharge, asymmetry); clinical breast examination (CBE) by healthcare provider; **mammography** (low-dose X-rays, standard screening generally recommended starting age 40–50, depending on risk and guidelines). (2) **Cervical cancer**—the **Papanicolaou (Pap) smear** detects precancerous changes (dysplasia) from HPV; liquid-based cytology is more accurate than conventional. HPV co-testing (HPV DNA/RNA test) increases detection; HPV-only testing is increasingly used. Recommended starting age 21 and repeated every 3–5 years if negative. **This is one of cancer's success stories**—Pap screening has reduced cervical cancer mortality by 70% in developed countries. In the Philippines, expanding Pap smear access is a DOH priority. (3) **Colorectal cancer**—**fecal occult blood test (FOBT)** annually; **fecal immunochemical test (FIT)** annually; **colonoscopy** every 10 years if negative (allows visualization and biopsy of lesions); **flexible sigmoidoscopy** every 5 years; **CT colonography** (virtual colonoscopy). Screening generally recommended starting age 45–50. (4) **Prostate cancer**—**prostate-specific antigen (PSA) blood test** and **digital rectal examination (DRE)**; recommendations vary (some organizations recommend screening after age 50 with shared decision-making; others suggest against routine screening due to overdiagnosis). (5) **Testicular cancer**—monthly **testicular self-examination (TSE)** in young men (ages 15–40); involves palpating each testicle gently for lumps, hardness, enlargement. (6) **Skin cancer**—regular self-inspection of moles using the **ABCDE rule**: **A**symmetry (is the mole asymmetrical?), **B**order irregularity (are edges jagged or uneven?), **C**olor variation (multiple colors within one mole?), **D**iameter over 6 mm (larger than a pencil eraser?), **E**volving (has it changed in size, shape, or color?). Any ABCDE features warrant dermatology evaluation. Teach patients to perform monthly skin checks. In the **Filipino context**, focus on cervical cancer screening (high incidence, preventable with HPV vaccine and Pap smear), breast cancer awareness and self-examination, and skin cancer prevention/early detection in fair-skinned individuals.

Cancer is one of the **top causes of death in the Philippines** (after heart disease and pneumonia). The **leading cancers** in the Filipino population are: (1) **Breast cancer**—most common cancer overall and leading cancer in Filipino women; incidence rising, likely due to increased awareness and screening, but also related to reproductive factors (late childbearing, fewer children), obesity, and hormone replacement therapy. (2) **Lung cancer**—second most common; strongly linked to high prevalence of smoking in men; also associated with occupational exposures (asbestos in construction) and air pollution. (3) **Colorectal cancer**—rising incidence, linked to aging population, Western diet (high fat, low fiber), and obesity. (4) **Liver cancer**—significant incidence due to endemic hepatitis B and C; most liver cancers in the Philippines are hepatocellular carcinoma (HCC) arising from chronic viral hepatitis. (5) **Cervical cancer**—remains common despite preventability; linked to HPV infection and limited Pap screening access in rural areas. (6) **Prostate cancer**—rising in incidence as the population ages; significant cause of cancer death in elderly men. Other notable cancers include esophageal, gastric, ovarian, and leukemia. **Government response**: **Republic Act No. 11215 (National Integrated Cancer Control Act/NICCA)** of 2019 established a comprehensive national cancer control program to improve cancer prevention, early detection, treatment, survivorship, and financial protection for patients. NICCA created the **Cancer Assistance Fund** to help poor and indigent cancer patients access treatment. The **Department of Health (DOH)** leads implementation through the National Cancer Control Program, coordinating with hospitals, local health departments, and NGOs. **Nursing roles aligned with NICCA/DOH**: Provide community health education on risk factors and warning signs; promote HPV and hepatitis B vaccination campaigns; counsel on smoking cessation; facilitate access to Pap smear and mammography screening through barangay health centers and DOH-partnered facilities; connect patients with Cancer Assistance Fund and treatment programs; address cultural beliefs and fatalism that delay care-seeking; and support survivorship and palliative care.

**Carcinogens** are agents that initiate cancer-causing mutations. Four categories: (1) **Chemical carcinogens**: tobacco smoke (polycyclic aromatic hydrocarbons, nitrosamines), asbestos (causes mesothelioma in construction workers and families), benzene (leukemia in industrial workers), aflatoxin (from contaminated food, liver cancer), pesticides, and formaldehyde. (2) **Physical carcinogens**: ultraviolet (UV) radiation from sun exposure (skin cancer, melanoma), ionizing radiation from nuclear accidents or radon exposure (leukemia, lung cancer), and repeated physical irritation (e.g., chronic irritation from ill-fitting dentures or tobacco use). (3) **Infectious agents**: **Human papillomavirus (HPV)** (cervical, anal, oropharyngeal cancers; preventable by HPV vaccine); **hepatitis B and C viruses** (HBV, HCV; liver cancer/HCC; preventable by hepatitis B vaccine); **Epstein-Barr virus** (EBV; Burkitt lymphoma, nasopharyngeal cancer); **human T-cell lymphotropic virus-1** (HTLV-1; adult T-cell leukemia); **Kaposi sarcoma-associated herpesvirus** (KSHV/HHV-8); and **Helicobacter pylori** (bacterium, stomach cancer, gastric lymphoma). (4) **Genetic/hereditary factors**: familial adenomatous polyposis (FAP; colon cancer), hereditary breast/ovarian cancer (BRCA1/BRCA2 mutations), hereditary nonpolyposis colorectal cancer (HNPCC/Lynch syndrome), Li-Fraumeni syndrome (p53 mutation; multiple cancers). Nurses must counsel on modifiable exposures (smoking, sun, alcohol) and support prevention strategies specific to each carcinogen type.

Mutations in proto-oncogenes (converting them to oncogenes) and inactivation of tumor suppressor genes (especially p53) are the **genetic hits** that initiate cancer during the Initiation phase. These mutations are irreversible. During the Promotion phase, repeated exposure to promoting agents (tobacco, alcohol, hormones, inflammation) stimulates proliferation of the mutated cell. During Progression, the accumulating cellular changes—loss of apoptosis, angiogenesis, invasion—drive malignancy. Thus, the genetic vulnerabilities set the stage, and environmental/lifestyle factors (often modifiable) drive progression.

Cancer cells that are **well-differentiated (Grade 1)** closely resemble normal tissue, grow slowly, and have the best prognosis. Conversely, **poorly differentiated/anaplastic (Grade 3–4)** cells look abnormal, grow rapidly, metastasize early, and have poor prognosis. Grading directly predicts aggressiveness: a Grade 4 tumor, even if small, is more dangerous than a large Grade 1 tumor because Grade 4 cells are more likely to invade, metastasize, and resist treatment.

**Stage 0 (Tis, N0, M0)** and **Stage I (small T, N0, M0)** are early, localized cancers with excellent prognosis; treatment is often curative (surgery ± chemotherapy/radiation). **Stage II–III** have local and regional lymph node involvement but no distant spread; prognosis is moderate; treatment aims for cure (multimodal therapy). **Stage IV (M1)** has distant metastasis; prognosis is guarded; treatment is usually palliative (aimed at symptom control and prolonged survival rather than cure). Thus, staging directly guides treatment intent (curative vs. palliative) and nursing priorities (aggressive symptom management vs. comfort care).

**Primary prevention** is most effective during the reversible **Promotion phase**, before Progression locks in malignancy. Smoking cessation, sun protection, diet changes, and vaccines work by stopping the promotion of initiated (but not yet progressive) cells. **Secondary prevention (screening)** detects cancer during early stages (**Tis to Stage I/II**) before symptoms and metastasis appear, when treatment is curative. Thus, primary prevention prevents initiation/promotion, and secondary prevention catches early progression when still curable.

Normal cells respect tissue boundaries through contact inhibition (stop dividing when they touch neighbors, forming an organized layer) and use apoptosis to remove old/damaged cells. Cancer cells lose contact inhibition (pile up chaotically) and evade apoptosis (damaged cells survive). This explains why benign tumors remain encapsulated and non-invasive (they retain some contact inhibition and apoptotic mechanisms) while malignant tumors infiltrate and metastasize (they have lost both safeguards).

**Carcinomas** (epithelial cancers: breast, lung, colorectal, gastric) spread via **lymphatic system** → regional lymph nodes → systemic circulation, explaining why lymph node status (N classification) is crucial for carcinoma staging. **Sarcomas** and some cancers preferentially spread **hematogenously** (through blood). The **first-line filter** for blood-borne cells is the **lungs** (most common metastatic site for many cancers); the **second filter** is the **liver**. Understanding routes guides where nurses watch for metastasis (e.g., monitor for respiratory symptoms in breast cancer patients—lung metastasis is common).

Each CAUTION sign points to a common cancer type or anatomic area: **C** (bowel/bladder cancer), **A** (skin/lip cancer), **U** (uterine/urinary cancer), **T** (breast/other lumps), **I** (GI cancers), **O** (skin cancer), **N** (lung/throat cancer). Nurses use CAUTION to educate patients on what warrants evaluation and to systematically assess symptomatic patients. A patient presenting with multiple CAUTION signs is at higher suspicion for cancer and needs prompt diagnostic workup.

Biopsy provides the tissue sample. **Histologic examination** confirms cancer type and assigns **grade** (based on cell differentiation). **Tumor size** in the biopsy specimen contributes to **T stage**. Supporting **imaging (CT, MRI, PET)** assesses local invasion and detects regional lymph node enlargement (**N stage**) and distant metastasis (**M stage**). Thus, biopsy is the first diagnostic step, and staging integrates biopsy findings with imaging.

Each cancer type has a specific, evidence-based screening test: **Pap smear** detects precancerous cervical changes (Stage 0/Tis), preventing cervical cancer if abnormalities are treated. **Mammography** detects early breast cancer (Tis–Stage II), allowing breast-conserving surgery. **Colonoscopy** removes adenomatous polyps (precancerous) and detects early colorectal cancer. **FOBT/FIT** screens asymptomatic individuals, prompting colonoscopy if positive. Screening is population-based (asymptomatic, at-risk) and most effective when applied to appropriate age groups and intervals, guided by evidence and risk.

**NICCA (RA 11215)** established the national cancer control program with goals of prevention, early detection, treatment, survivorship, and financial support. **DOH** implements through the National Cancer Control Program, working with health facilities and local governments. **Nurses** contribute across all levels: community health nurses promote HPV/hepatitis B vaccines and smoking cessation (primary prevention); nurses in clinics facilitate Pap smear and mammography (secondary prevention); oncology nurses provide treatment support; palliative care nurses support survivorship and end-of-life care. Nurses also address cultural barriers and ensure equitable access via the Cancer Assistance Fund.