Introductory Oncology Lecture Notes

Cancer Overview

• Definition & Core Characteristics

  • Diseases marked by uncontrolled cellular growth & division.
  • Cells can invade adjacent tissue, spread (metastasize) to distant organs → organ dysfunction.
  • Rapid, unchecked growth forms masses called tumors.
  • Tumors may be benign (non-invasive) or malignant (invasive, metastatic).
  • > \text{> 200} distinct cancer types; can arise in almost any body tissue.

• Metastasis Mechanics

  • Cancerous cells travel primarily through the lymphatic system (and blood) to establish new tumors.
  • Sentinel-node biopsy (example: suspected breast cancer)
  • The first lymph node in a regional chain is sampled.
  • No tumor cells in sentinel node ⇒ likely no spread.
  • Tumor cells present ⇒ heightened concern for systemic metastasis.

Lung Cancer

• Epidemiology & Etiology

  • Malignant tumors originating in lung tissue; leading cause of cancer mortality worldwide.
  • \approx 80\% linked to cigarette / tobacco smoke, yet can occur in never-smokers.
  • Additional risks: second-hand smoke, radon, asbestos (mesothelioma), industrial/chemical fumes, fine particulate exposures (e.g., nail salon dust, carpet fibers), family/genetic predisposition.
  • Gender trend: men historically show higher incidence (partly due to higher smoking prevalence).

• Classification

  • Small-Cell Lung Cancer (SCLC)

  • "Small" cellular morphology; highly aggressive, fast growth & early spread.

  • Represents 13-15\% of lung cancers.

  • Extent described as limited vs extensive disease.

  • Non-Small-Cell Lung Cancer (NSCLC) – \approx most common category.

  • Larger cell (a.k.a. “oat cell”) morphology; slower, smoldering course, common in elderly.

  • Histologic sub-types

    • Adenocarcinoma – outer/peripheral lung; most frequent overall.
    • Squamous Cell Carcinoma – originates in bronchial epithelium; earlier symptom onset.
    • Large Cell Carcinoma – rapid growth, late presentation.

  • Staging: Stage\;0 \rightarrow 4 (higher stage = greater spread).

• Clinical Presentation

  • Early/General
  • Persistent, dry or “nagging” cough
  • Central chest pain (from chronic cough)
  • Dyspnea / shortness of breath (SOB)
  • Unexplained weight loss (classic cancer hallmark)
  • Hoarseness, wheezing, hemoptysis
  • Late / Metastatic Signs
  • Bone pain (back, hip) – skeletal mets
  • Enlarged neck or hilar lymph nodes
  • Neurologic events: seizures, balance issues – brain mets
  • Jaundice (yellow skin/eyes) – hepatic mets

• Management Modalities

  • Surgery (e.g., lobectomy)
  • Systemic therapy
  • Traditional chemotherapy (kills malignant & healthy rapidly dividing cells → mucositis, alopecia, nail/skin changes)
  • Targeted therapy (molecular-specific, spares more normal tissue)
  • Immunotherapy (stimulates patient’s immune system to attack tumors)
  • Risk-reduction counseling: smoking cessation, protective gear for occupational exposures, diet/exercise, air-quality control.

Colorectal (Colon) Cancer

• Current Concerns

  • Rising incidence, even in younger adults (<50 yrs).

• Risk Factors

  • Age > 50 (screen at 45 if elevated risk).
  • Family / personal history → encourage genetic testing for high-risk mutations.
  • Race & Sex: higher rates in African Americans and women.
  • Chronic inflammatory bowel disease (IBD) – persistent inflammation induces malignant transformation (same concept with GERD→esophageal cancer).
  • Lifestyle: physical inactivity, high red/processed-meat intake, obesity, alcohol, smoking.
  • Processed foods: cheaper to produce, nutrient-poor “crap” – clinician teaching point on diet quality.

• Pathophysiology & Detection

  • Begins as precancerous polyps on colonic mucosa.
  • Visible & removable only via colonoscopy.
  • Non-invasive stool DNA tests (e.g., Cologuard) detect occult blood/abnormal cells but cannot visualize polyps.
  • Screening
  • Colonoscopy every 10 yrs (or per findings) starting at \ge 50 (or 45 if high-risk).

• Signs & Symptoms

  • Altered bowel habits; tenesmus (constant urge to defecate despite empty rectum).
  • Fatigue (often from iron-deficiency anemia due to slow bleeding).
  • Rapid, unexplained weight loss.
  • Abdominal pain, rectal bleeding, occult blood in stool.

• Prognostic Note

  • Late-stage disease is "out of the barn" → difficult therapy, poor outcomes (illustrated by actor Chadwick Boseman’s rapid decline).

• Treatment Goals & Methods

  • Polypectomy during colonoscopy; segmental colectomy for clustered polyps.
  • Adjuvant chemotherapy, surgery, +/- radiation for metastatic spread.

Brain Cancer

• Primary vs Secondary

  • Primary tumors arise in brain tissue.
  • Gliomas / Glioblastomas – glial cell origin; highly aggressive, poor prognosis.
  • Meningiomas – from meningeal membranes; usually benign but potential malignancy.
  • Medulloblastomas – cerebellar tumors, primarily pediatric.
  • Pituitary adenomas, Schwannomas (rare).
  • Secondary (Metastatic) – spread from lung, melanoma, breast, etc. Certain cancers have organ “preferences” (melanoma → brain).

• Clinical Features (often vague; need high suspicion)

  • Communication deficits, word-finding problems.
  • Hearing changes (ringing, abnormal sensations).
  • Memory lapses, cognitive decline.
  • Balance/gait abnormalities.
  • Nausea/vomiting, increasing drowsiness / lethargy.
  • Personality/behavior changes, new-onset seizures (common ER presentation).

• Therapeutic Options

  • Radiation therapy (external beam, stereotactic).
  • Chemotherapy & Targeted agents.
  • Tumor Treating Fields (TTF) – alternating electric fields inhibiting mitosis.
  • Surgery for accessible masses.
  • Emerging modalities: cold atmospheric plasma.

Leukemia (Liquid Tumors)

• Bone-Marrow Biology

  • Bone marrow = "factory" for blood cells (RBC, WBC, platelets).
  • Leukemia = malignant overproduction of immature WBCs (blasts).
  • \text{High blast count} \Rightarrow dysfunctional immunity & marrow crowd-out → anemia, thrombocytopenia.

• Risk Factors

  • Genetic predisposition, radiation/chemical exposure, smoking, gender, ethnicity, family history.

• Major Types

  Type	Age Group	Key Notes
  ALL (Acute Lymphocytic)	Predominantly children	Rapid onset
  AML (Acute Myeloid)	Older adults > children	Rapid
  CLL (Chronic Lymphocytic)	Most common adult leukemia; post-middle age	Indolent onset
  CML (Chronic Myeloid)	Middle-age onward	May present earlier than CLL

• Symptoms (systemic & marrow failure)

  • Weight loss, fever, recurrent infections (non-functional WBCs).
  • SOB, muscle/joint pain, profound fatigue, appetite loss.
  • Painless lymphadenopathy; hepatosplenomegaly (enlarged liver/spleen).
  • Night sweats, easy bruising/bleeding, petechiae.

• Diagnosis

  • CBC with differential: elevated WBC count & \uparrow blasts.
  • Bone-marrow biopsy/aspiration (posterior iliac crest common site): large trocar needle – twist, core, extract.
  • Imaging, lumbar puncture (identify CNS involvement), detailed history.

• Treatment Strategies

  • Chemotherapy (multi-drug induction & consolidation protocols).
  • Targeted therapy (e.g., tyrosine-kinase inhibitors in CML).
  • Stem-Cell / Bone-Marrow Transplantation (curative intent in many acute leukemias).
  • Radiation (less common; CNS prophylaxis in ALL).

Cross-Cutting Concepts & Clinical Pearls

• Hallmark Cancer Symptom: Unexplained, unintended weight loss should always prompt malignancy evaluation.
• Inflammation → Carcinogenesis: chronic irritation & tissue turnover (IBD, GERD) elevate cancer risk; proactive anti-inflammatory therapy is preventive.
• Node Assessment
  • Hard, fixed lymph nodes → higher suspicion of malignancy.
  • Soft, mobile, “spongy” nodes often benign/reactive.
• Chemotherapy Side-Effects are linked to destruction of other rapidly dividing healthy cells (mucosa, hair follicles, nail beds). Patient education on oral care, alopecia expectation, infection prevention is essential.
• Occupational / Environmental Safety
  • Encourage PPE (masks, ventilation) for nail technicians, mechanics, textile workers, etc.
  • Advocacy challenge: variable regulatory enforcement (e.g., OSHA limitations mentioned).
• Lifestyle Modification
  • Diet rich in whole foods, plant fibers; limit processed meats.
  • Regular exercise, weight control, smoking cessation, moderated alcohol intake.

Equation & Numeric References Snapshot

• Tumor staging: Stage\;0,1,2,3,4 (increasing severity/spread).
• Lung cancer attributable to smoking: \approx 80\%.
• Small-cell lung cancer prevalence: 13-15\% of all lung cancers.
• Colonoscopy screening initiation: \ge 50 yrs (or 45 yrs if elevated risk).
• Sentinel node concept: absence of tumor cells in the first lymph node ⇒ \text{No regional metastasis detectable}.