Cancer
# Lecture Summary
Subject: Oncology / Cancer pathophysiology (Nursing / PA student level)
## Key Learning Points
- Cancer is a disorder of cell proliferation and differentiation caused by genetic mutation; only about 5–10% of cancers are inherited.
- Incidence estimates: ~1.9 million to 2 million new cancer cases projected in 2024 in the U.S. Major causes of cancer death remain lung/bronchus and colorectal cancers; breast and prostate cancers together account for a large proportion of cases.
- Important tumor concepts: benign vs malignant, metastasis (lymphatic spread, seeding), angiogenesis, anchorage independence, carcinoma in situ.
- Genetic contributors: BRCA1/BRCA2 (familial breast/ovarian risk), Philadelphia chromosome (9;22 translocation) in certain leukemias, p53 dysfunction (implicated in ~50% of cancers).
- Major modifiable risk factors: tobacco (strong link to lung, mouth, esophagus, bladder, kidney), alcohol (liver, mouth, esophagus, stomach), radiation (UV and strong exposures), chemical exposures, diet/food preparation (charred foods, additives), persistent infections (hepatitis, HPV, H. pylori). Emerging concerns: vaping and marijuana — limited long-term data but inhaled toxins are of concern.
- Screening and early detection decrease mortality: mammography, low-dose CT scans for high-risk smokers, Pap/HPV screening, targeted tumor markers and imaging; TNM staging and biopsy remain central to diagnosis and planning.
- Treatments: surgery (wide margins), radiation (now more targeted), chemotherapy (systemic and targeted agents), immunologic/targeted therapies; treatment approaches and veterinary oncology options are evolving rapidly.
- Clinical manifestations vary widely; common signs include unexplained weight loss/cachexia, fatigue (most common), pain, bleeding or purpura (low platelets), hair loss with chemotherapy, and psychosocial effects (depression/anxiety). Pain and comfort care play central roles in advanced disease.
- Survival metrics: cancer survival commonly reported as 5-year survival rates; average age of onset ~66 years. Cancer death rates have declined (instructor cited a ~27% decrease from 2001–2020), attributed to screening, prevention campaigns, vaccines, and improved treatments.
## Definitions
- Tumor: new growth / piece of tissue growing where it should not be.
- Malignant: cancerous tumor; capable of invasion and metastasis.
- Benign: noncancerous tumor, well-differentiated, often encapsulated, less likely to spread (can still be life-threatening depending on location, e.g., brain).
- Proliferation: rapid cell division/growth.
- Differentiation: how specialized cells are and how they resemble normal tissue.
- Metastasis: spread of cancer cells from primary site to distant sites.
- Seeding: form of metastasis where tumor cells break off and implant elsewhere (visualized as dandelion "puff" analogy; common with ovarian cancer).
- Angiogenesis: tumor-driven growth of new blood vessels to supply the tumor.
- Anchorage independence: cancer cells' ability to grow without normal basement membrane attachment.
- Carcinoma in situ (CIS): tumor cells that have not invaded through the basement membrane.
- Sentinel lymph node: the first lymph node(s) to which a tumor drains; biopsied to check for spread.
- Telomeres: protective chromosome end structures; cancer cells often maintain telomeres to allow continued division.
- p53: tumor suppressor protein that triggers apoptosis of damaged cells; dysfunction is common in cancers (~50% implicated).
- BRCA1 / BRCA2: inherited genes associated with high familial risk for breast and ovarian cancer (also linked to male breast and prostate cancer risk).
- Philadelphia chromosome: specific translocation between chromosomes 9 and 22 associated with certain leukemias.
- TNM staging: Tumor-Node-Metastasis, system describing tumor size, lymph node involvement, and distant spread.
- PSA: prostate-specific antigen; a blood test historically used for prostate cancer screening but increasingly controversial due to false positives/negatives.
- Purpura: purple skin spots caused by bleeding into the skin (from low platelets/coagulopathy).
- Cachexia (referred to in lecture as "anorexia or chytrexia"): cancer-associated wasting with rapid weight/muscle loss due to high tumor metabolism.
## Detailed Topic Notes
(Topics follow the order presented in lecture; instructor content is summarized with student questions identified in-line.)
### Overview & Epidemiology
Instructor presentation:
- Cancer is derived from the Greek word for "crab" (tumor with appendages).
- U.S. estimated new cancer cases: instructor mentioned approximately 1.9 million and cited a projection of about 2 million new cases in 2024 (American Cancer Society data referenced).
- Most common cancers by sex: For females, breast cancer #1; for males, prostate cancer #1. For both sexes, lung and bronchus rank high (often #2 in sex-specific lists). When combined, lung/bronchus is the leading cause of cancer death; colorectal cancers often rank #2 overall.
- Breast and prostate cancers combined account for nearly half of all cancer cases.
- Average age of cancer onset ~66 years.
- Five-year survival rates are the standard measure of survival outcomes.
Instructor commentary/clinical context:
- More cancer cases are being detected now and treatments are improving (examples: BRCA testing, targeted therapies, veterinary oncology advances).
- Screening is emphasized as a major driver of improved outcomes and mortality reduction.
In-Class Exercise/Activity:
- None presented.
### Definitions: Benign vs Malignant Tumors; Basic Tumor Biology
Instructor presentation:
- Benign tumors: well-differentiated, encapsulated, do not metastasize, often removable; can still be life-threatening depending on location (e.g., intracranial tumors causing compression).
- Malignant tumors: gross cell abnormalities, poorly differentiated, autocrine signaling (self-stimulating), rapid growth, ability to metastasize, anchorage independence, angiogenesis, and telomere maintenance (allowing continued division).
- Carcinoma in situ: localized neoplastic epithelial cells that have not breached the basement membrane.
- Mechanisms enabling cancer survival/expansion include loss of tumor suppression (p53 dysfunction), ability to evade apoptosis, and attraction/alteration of surrounding healthy cells (high affinity for healthy cells leading to invasion).
In-Class Exercise/Activity:
- None presented.
### Pathogenesis and Genetics
Instructor presentation:
- Core message repeated: the origin of cancer is genetic mutation. Most mutations are acquired; 5–10% of cancers are inherited.
- Examples of inherited genetic risk:
- BRCA1 and BRCA2: high familial risk for breast and ovarian cancer; men with BRCA also at increased risk for breast and prostate cancers (instructor estimated an ~80% risk in those with the mutation but noted variability).
- Chromosomal translocation example:
- Philadelphia chromosome: translocation between chromosome 9 and 22 (9;22) implicated in certain leukemias; abnormality occurs at a chromosomal breakpoint important in white blood cell proliferation.
- p53 dysfunction: ~50% of cancers are associated with p53 pathway abnormalities—p53 normally triggers apoptosis of damaged cells.
- Epigenetics: environment and gene regulation (genes turned on/off, translocations) contribute to cancer development.
- The immune system may initially suppress tumor growth, but cancer cells can eventually evade immune control.
Student question (vaping/marijuana):
- Students asked about vaping and marijuana risks. Instructor response: long-term data are limited; vaping and marijuana still involve inhaling substances that may harm lung tissue; federal legal status of marijuana has limited research; medical formulations of cannabinoids exist for symptom control (e.g., appetite stimulation in chemotherapy patients).
In-Class Exercise/Activity:
- None presented.
### Metastasis and Routes of Spread
Instructor presentation:
- Metastasis steps: tumor growth → mutation allowing detachment → invasion into local tissue → entry and travel via lymphatic or blood systems → establishment at distant sites.
- Lymphatic spread is common: cancers frequently first spread to regional lymph nodes; sentinel lymph nodes are biopsied to assess spread.
- Angiogenesis: tumors can induce growth of new blood vessels to sustain growth.
- Seeding: descriptive for processes such as ovarian cancer shedding cells that implant across peritoneal surfaces (dandelion seed analogy).
- Carcinomas have predictable patterns for some cancers (e.g., breast cancer commonly spreading to axillary nodes, possible spread to liver and lungs). Some cancers (e.g., testicular) have characteristic but variable spread patterns.
- Anchorage independence and telomere maintenance permit colonization of distant tissues.
In-Class Exercise/Activity:
- None presented.
### Risk Factors and Prevention
Instructor presentation (major risk factors covered in order):
- Tobacco smoking: strongest known risk factor for lung cancer and also strongly associated with mouth, esophagus, throat, bladder, and kidney cancers. Cigarettes contain >700 chemicals. Inhaled toxins are metabolized by the kidneys and liver—bladder/kidney involvement related to toxin excretion.
- Screening: low-dose CT chest scans recommended for certain long-term smokers (U.S. Preventive Task Force guidelines) to detect early lung tumors.
- Vaping and hookah: increasing prevalence, especially among younger patients; long-term cancer risk data are limited but inhaled toxins remain a concern.
- Marijuana: limited federal research; medical marijuana formulations used to manage chemotherapy-induced symptoms (e.g., appetite stimulation); smoking marijuana still poses potential lung harm per CDC statements on lung tissue damage/scarring; non-smoking routes may reduce lung harm.
- Alcohol: chronic heavy use associated with liver cancer and cancers of mouth, esophagus, stomach.
- Diet and food preparation: emerging links to cancer risk (charred foods, additives, dyes); international differences (examples: European vs U.S. food additive regulations).
- Radiation: strong exposures (bombings, high-dose radiation) and ultraviolet light (skin cancer) are established carcinogens.
- Infectious agents: chronic viral infections can lead to cancer (hepatitis B/C → liver cancer; HPV → cervical cancer; H. pylori → gastric cancer). Notably, hepatitis C now has curative therapies available; HPV vaccination and screening reduce cervical cancer risk.
Instructor emphasis:
- Prevention heavily relies on screening (mammograms, Pap/HPV tests, low-dose CT for eligible smokers), vaccines (HPV, hepatitis), public health campaigns (tobacco control), and behavioral change.
In-Class Exercise/Activity:
- None presented.
### Clinical Manifestations of Cancer
Instructor presentation:
- Presentation is variable; early signs can be subtle and non-specific. Examples given: painless hematuria as a first sign in a case that was lung cancer metastasis.
- Common clinical features as cancer progresses:
- Unintentional weight loss and cachexia (rapid muscle and fat loss due to high tumor metabolic demand).
- Fatigue (most common symptom).
- Pain (may be early or later depending on location; e.g., spinal compression → back pain and neurologic deficit).
- Bleeding and purpura (due to platelet and marrow suppression).
- Hair loss (an expected side effect of many chemotherapeutic agents because hair follicles contain rapidly dividing cells).
- Psychological effects: high rates of anxiety and depression; mental health important to address.
- End-of-life and advance care planning variability: patients have different preferences for life-sustaining treatments and comfort measures.
- Specific physical exam points:
- Breast exam including axillary nodes; tail of Spence can be the first site of breast tumor-related changes.
- Skin exam for changing moles (melanoma risk); annual skin checks recommended.
Student question (male breast exam):
- Student noted males can get breast cancer and asked about breast exams in male patients. Instructor: Yearly breast examinations should be done in males as well; male breast exams are often overlooked in primary care.
In-Class Exercise/Activity:
- None presented.
### Diagnosis and Screening
Instructor presentation:
- Screening modalities discussed:
- Mammography: recommended starting at age 45–50 (individualize earlier if family history/BRCA).
- Low-dose CT chest for eligible smokers (US Task Force-based screening).
- Pap/HPV screening for cervical cancer prevention and detection.
- PSA for prostate cancer: available but increasingly discouraged as routine screening due to false positives/negatives; decision individualized.
- Diagnostic steps when suspicion arises:
- Biopsy of suspicious lesion (primary diagnostic procedure): evaluate differentiation, tumor type.
- Sentinel lymph node biopsy for regional spread assessment.
- Tumor markers and laboratory clues (e.g., hypercalcemia can suggest parathyroid/thyroid involvement or paraneoplastic processes).
- Imaging studies to localize tumors and assess metastasis.
- TNM staging to describe tumor size (T), nodal involvement (N), and metastasis (M).
- Example pathologic images discussed: basal cell carcinoma (skin), oral squamous cell carcinoma; examples of CT imaging of tumors and seeding in the abdomen (ovarian cancer).
In-Class Exercise/Activity:
- None presented.
### Treatment Modalities
Instructor presentation:
- Main treatment options:
- Surgery: removal of tumor with wide margins when possible; may be curative for localized tumors. Surgical candidacy depends on patient age, frailty, tumor location, and patient preference.
- Radiation therapy: historically more diffuse; now more targeted/pinpointed to minimize collateral tissue damage. Used for curative and palliative intents.
- Chemotherapy: targets rapidly dividing cells (hence side effects on bone marrow, hair follicles, mucosa). Shift toward targeted systemic agents and immunotherapies with fewer systemic side effects in some cases.
- Combination therapy (chemoradiation) remains common. Newer targeted agents and immunotherapies are rapidly evolving.
- Research directions:
- Restoring or targeting p53 function is an area of ongoing study.
- Increasing personalization of therapy and improving quality-of-life outcomes, including in veterinary oncology (case example: Fonzie, a dog with lymphoma receiving targeted chemotherapy to extend quality life).
- Symptom management and palliative care:
- Pain control is prioritized in cancer patients; opioid use is judged differently in end-of-life care (comfort-focused rather than strict opioid-limiting policies).
- Addressing psychosocial needs, body image issues (reconstruction vs different patient choices), and end-of-life preferences are essential components of care.
Student question (dogs and chemo side effects; will dogs lose fur?):
- Instructor acknowledged veterinary oncology differences (dogs may not lose fur the same way; instructor to follow up).
In-Class Exercise/Activity:
- None presented.
### Prognosis and Trends / Public Health Impact
Instructor presentation:
- Survival measurement: 5-year survival rates are used to report outcomes.
- Cancer death rate trends: instructor cited a decline in cancer death rates (stated a ~27% decrease from 2001–2020); attributed to earlier detection (screening), vaccines, prevention campaigns, and improved therapies.
- Emphasized the growing number of treatment options and evolving standards of care; veterinary oncology is also advancing.
In-Class Exercise/Activity:
- None presented.
### Patient Care, Communication, and Psychosocial Considerations
Instructor presentation:
- Cancer patients present at many points of the health system (PCP visits, ER, med-surg floors, ICU, hospice). Providers across settings must be prepared to assess and discuss screening, diagnosis, treatment options, and advance directives.
- Communication challenges: patients vary in openness to discussing prognosis and end-of-life care. Families may have conflict in stressful situations; clinicians should be prepared for complicated family dynamics.
- Importance of advocacy: clinicians and patients should ensure recommended screenings occur (provider reminders, patient self-advocacy).
- Support services: wigs, prostheses, nutritional support, and mental health resources are important; oncology nursing plays a key supportive role.
In-Class Exercise/Activity:
- None presented.
## Questions and Answers Highlights
(Note: no separate, dedicated Q&A session; instead student questions were integrated into lecture and are included within topic sections above. Below are selected question/answer exchanges recorded during the lecture.)
- Q: Do males get breast exams? (Student)
A: Yes — males can get breast cancer; yearly breast examinations should be considered in male patients. (Instructor)
Key insight: Male breast cancer exists and is often overlooked in routine care.
- Q: What do we know about vaping and hookahs? (Student)
A: Long-term data are limited; vaping is popular among younger patients and likely exposes lungs to toxins, so concern exists though definitive long-term cancer links are not yet established. (Instructor)
Key insight: Emerging exposures require surveillance and research; counseling about inhalation routes is advisable.
- Q: What about marijuana and cancer risk/benefit? (Student)
A: Research constrained by federal legal status; medical cannabinoids are used symptomatically in oncology (e.g., appetite stimulation), but smoking marijuana can harm lung tissue per CDC; alternate routes of administration may reduce pulmonary risk. (Instructor)
Key insight: Distinguish therapeutic medical use (compounded/regulated) from recreational inhalation; need for more research.
- Q: Can cancer present with painless hematuria? (Student/Instructor example)
A: Yes — painless hematuria was described as an initial presenting sign in a case that later was found to be related to metastatic disease; nonspecific findings can hide serious disease. (Instructor)
Key insight: Non-specific symptoms warrant appropriate evaluation especially in high-risk patients.
## Exam Callouts
- Know definitions and differences: benign vs malignant, metastasis, seeding, carcinoma in situ.
- Remember the origin of cancer: genetic mutation (repeat emphasized).
- Know key hereditary risks: BRCA1/2 (breast/ovarian) and the Philadelphia chromosome (9;22) association with leukemia.
- Screening modalities and recommended rationale: mammography (age considerations), low-dose CT for eligible smokers, Pap/HPV screening; understand TNM staging and sentinel lymph node concept.
- Clinical manifestations to recognize: unexplained weight loss/cachexia, fatigue (most common), pain, unexplained bleeding/purpura, persistent hoarseness, changing moles, nonhealing sores — these should prompt evaluation.
- Be familiar with common metastatic patterns and the role of lymphatics; understand angiogenesis and anchorage independence as cancer behaviors.
- Be aware of p53’s role and that ~50% of cancers involve p53 dysfunction (important for future targeted therapy knowledge).