Lung Cancer

Small Cell Lung Cancer (SCLC)

•    Accounts for ~15% of cases

•    Central, arises from neuroendocrine Kulchitsky cells

•    Highly aggressive, rapid doubling time, early widespread metastases:

o    Brain (common cause of paraneoplastic encephalopathy)

o    Liver

o    Bone

o    Adrenal glands

•    Paraneoplastic syndromes:

o    SIADH → hyponatraemia (euvolaemic)

o    Ectopic ACTH → Cushing's syndrome

o    Lambert-Eaton myasthenic syndrome → proximal muscle weakness improves with use

•    Treatment: usually chemotherapy ± radiotherapy, surgery rare due to early spread

Non-Small Cell Lung Cancer (NSCLC)

•    ~85% of lung cancers; subtypes:

Squamous cell carcinoma

•    Central, often cavitating

•    Strong smoking association

•    Produces PTHrP → hypercalcaemia

•    Can cause obstructive pneumonia

Adenocarcinoma

•    Peripheral, subpleural

•    Most common type in non-smokers and women

•    May present as solitary pulmonary nodule

•    May arise in scarred lung ("scar carcinoma")

Large cell carcinoma

•    Poorly differentiated, can be central or peripheral

•    Rapid growth, early metastasis

•    Associated with poor prognosis

Diagnostic Pathway

•    Initial: CXR (e.g., hilar mass, effusion, collapse)

•    CT thorax and upper abdomen: staging, operability

•    PET-CT: identifies occult metastases

•    Tissue diagnosis:

o    Bronchoscopy ± endobronchial ultrasound (EBUS) for central lesions/lymph nodes

o    CT-guided percutaneous biopsy for peripheral lesions

Colorectal Cancer

Right-sided (proximal)

•    Features:

o    Iron deficiency anaemia (occult bleeding)

o    Weight loss

o    Mass in right iliac fossa

•    More common in Lynch syndrome (HNPCC)

Left-sided (distal)

•    Features:

o    Change in bowel habit (often alternating diarrhoea and constipation)

o    Obstructive symptoms (colicky pain, distension)

o    Fresh rectal bleeding

•    Apple-core lesion on barium enema (historical)

Rectal

•    Features:

o    Tenesmus (feeling of incomplete emptying)

o    Urgency

o    Rectal bleeding

•    Digital rectal exam important

Molecular subtypes

•    Microsatellite instability (MSI): seen in Lynch syndrome

•    Chromosomal instability (APC pathway): sporadic majority

Breast Cancer

Types

•    Invasive ductal carcinoma (~80%): most common type, firm ("stellate" on imaging)

•    Invasive lobular carcinoma:

o    Tends to be bilateral and multicentric

o    "Single-file" cells histologically

Molecular subtypes

•    Triple negative (ER-, PR-, HER2-):

o    More aggressive, higher risk of early recurrence

o    Common in BRCA1 mutation carriers

•    HER2-positive:

o    Targeted therapy: trastuzumab (Herceptin)

o    Requires cardiac monitoring (risk of cardiomyopathy)

Risk factors

•    Nulliparity

•    Late first pregnancy

•    Early menarche, late menopause

•    Hormone replacement therapy

Screening

•    Mammography screening (UK): age 50–70, every 3 years

Prostate Cancer

Features

•    Age-related, very common in elderly men

•    Arises from peripheral zone → often asymptomatic early

•    PSA:

o    Typically >4 ng/mL (age-adjusted cut-offs used)

o    Can also rise with prostatitis and BPH

•    Metastases:

o    Bone metastases → osteoblastic/sclerotic lesions

o    Features: back pain, pathological fractures, raised ALP, hypercalcaemia (rare)

Diagnosis

•    Digital rectal exam: hard, irregular prostate

•    Transrectal ultrasound-guided biopsy for histology

•    MRI for staging (locoregional spread)

Ovarian Cancer

Features

•    Often late presentation with vague symptoms:

o    Abdominal distension ("bloating")

o    Early satiety

o    Pelvic/abdominal pain

o    Urinary urgency

•    CA-125:

o    Elevated in ~80%, but non-specific

o    Also rises with benign conditions (e.g., endometriosis, menstruation, liver disease)

Types

•    High-grade serous carcinoma: most common and aggressive

•    Mucinous, endometrioid, clear cell: less common

Risk factors

•    BRCA1/2 mutations (lifetime risk up to 40% in BRCA1)

•    Nulliparity, infertility

•    Early menarche, late menopause

Protective factors

•    Pregnancy, breastfeeding

•    Oral contraceptive pill

Extra Revision Pearls

•    Lynch syndrome: think right-sided colon cancer and associated endometrial cancer

•    BRCA1: more often triple negative breast cancer, higher ovarian risk

•    Prostate cancer metastases: sclerotic vs lytic bone metastases (breast can be mixed, myeloma purely lytic)

•    CA-125: not a screening tool but useful in monitoring treatment response