Lung Cancer (Pistun) - 12/5/16 Flashcards
Three major categories of cancers of the thorax
-
Primary malignancies
- Occurs inside lung (in lung tissue itself)
- May originate in epithelial or mesodermal elements
-
Metastatic disease to the lung
- From other organs that metastasize to the lung (not v common)
- Lymphangitic - breast, stomach, pancreas, ovary, prostate, lung
- Hematogenous - colon, thyroid, kidney, testes, sarcomas
-
Mediastinal tumors
- Thymoma (tumor originating from epithelial cells of thymus)
- Teratoma
- Thyroid Cancer (starts at neck and some processes descend into thorax)
- “Terrible” Lymphoma
Lung cancer = most common cause of cancer mortality in the US.
What is the average at presentation?
60 years
Genetic and Racial Differences
- Women = 1.5x higher risk than men
- Higher incidence and mortality in AA males than white males
- Lung cancer requires large number of genetic lesions
- Activation of dominant oncogene: ras, myc, Her-2/neu
- Inactivation of tumor suppressor gene or recessive oncogenes: p53, 3p, Rb
3 key risk factors
-
Cigarette smoke
- Contains over 60 carcinogens
- 85% of lung cancer occurs in smokers
- PAH (polycyclic aromatic hydrocarbons) and arsenic = mutagenic
- Cancer risk directly related to duration and amount of smoking (‘pack-years’)
-
Radon
- Formed by radioactive decay of uranium (present in soil)
- Accumulates in closed spaces (i.e. basements)
- 2nd most frequent cause of lung carcinoma in US
- Inc. risk of lung cancer also seen in uranium miners
- Asbestos
- Naturally occuring mineral
Presenting symptoms are nonspecific (4)
- Cough
- Weight loss
- Hemoptysis
- Postobstructive pneumonia
What does imaging reveal?
Solitary nodule (‘coin-lesion’); biopsy necessary for dx of cancer
Can have benign lesions (often occur in younger patients) can also produce ‘coin lesion’
Examples:
- Granuloma - often due to TB or fungus
- Bronchial hamartoma - benign tumor composed of lung tissue and cartilage (often calcified on imaging)
Lung carcinoma classically divided into 2 categories
- Small cell carcinoma (15%) - usually can’t be operated on, treat w/ chemo
-
Non-small cell carcinoma (85%) - treated upfront w/ surgery, does NOT respond well to chemo
- Adenocarcinoma (40%)
- Squamous cell carcinoma (30%)
- Large cell carcinoma (10%)
- Carcinoid tumor (5%)
Small Cell Carcinoma
Characteristic Histology
Association
Location
Comment
Characteristic Histology
- Poorly differentiated small cells
- Arises from neuroendocrine (Kulchitsky) cells
Association
- Male smokers
Location
- Central
Comment
- Rapid growth and early metastasis
- May produce ADH or ACTH
- May cause Eaton-Lambert Syndrome (type of paraneoplastic syndrome)
- Pts develop antibodies against pre-synaptic calcium channels
- Result: possibility of muscle weakness
Squamous Cell Carcinoma (30%)
Characteristic Histology
Association
Location
Comment
Characteristic Histology
- Keratin pearls
- Intercellular bridges
Association
- Most common tumor in male smokers
Location
- Central
Comment
- May produce PTHrP → give pts hypercalcemia
- Associated with Pancoast’s syndrome (tumor in apex), hypercalcemia
- Cavitation common
Adenocarcinoma (40%)
Characteristic Histology
Association
Location
Comment
Characteristic Histology
- Glands or mucin
Association
- Most common tumor in nonsmokers and female smokers
Location
- Peripheral
Comment
- Metastatic spread via vascular/lymphatic channels
- Metastatic disease at diagnosis common (since it sits inside lung parenchyma, you don’t feel it - no pain receptors… you’ll know something is wrong once yous tart exhibiting other symptoms such as cough, hemoptysis, etc…)
Large Cell Carcinoma (10%)
Characteristic Histology
Association
Location
Comment
Characteristic Histology
- Poorly differentiated large cells (no keratin pearls, intercellular bridges, glands, or mucin)
- Abundant cytoplasm
Association
- Smoking
Location
- Central or peripheral
Comment
- Poor prognosis
Carcinoid tumor (5%)
Characteristic Histology
Association
Location
Comment
Characteristic Histology
- Well differentiated nueorendocrine cells
- Chromogranin positive
Association
- Not related to smoking
Location
- Central or peripheral
- When central, classically forms a polyp-like mass in bronchus
Comment
- Low-grade malignancy
- Rarely, can cause carcinoid syndrome
Bronchioloaveolar carcinoma (subtype of adenocarcinoma)
Characteristic Histology
Association
Location
Comment
Characteristic Histology
- Columnar cells that grow along pre-existing bronchioles and alveoli (lepidic growth)
- Arises from Clara cells
Association
- Not related to smoking
Location
- Central or peripheral
- When central, classically forms a polyp-like mass in the bronchus
Comment
- Low-grade malignancy
- Rare, can cause carcinoid syndrome
- Appears on CXR like infiltrate or mass
Physical Exam: Digital Clubbing
When you get any lung disease adn don’t get enough oxygen, connective tissue starts to grow (CT loves hypoxic states).
There is a lot of CT at the nail beds b/c nails are continually growing.
Staging Non-Small Cell Carcinomas
Two questions:
Is tumor resectable?
Is patient operable?
TNM classification
T: Tumor size and local extension
- Pleural involvement classically seen w adenocarcinoma
- Obstruction of SVC leads to distended head and neck veins w edema and blue discoloration of arms and face (SVC syndrome)
- Involvement of recurrent laryngeal (hoarseness) or phrenic (diaphragmatic paralysis) n.
- Compression of sympathetic chain leads to Horner syndrome - due to Pancoast tumor
- Ptosis (drooping eyelid)
- Miosis (pinpoint pupil)
- Anhidrosis (no sweating)
N: Spread to regional lymph nodes (hilar and mediastinal)
M: Unique site of distant metastasis = adrenal gland
Overall, 15% 5-yr survival; often presents late due to absence of effective screening method
