Etiology/Classification

Second most common cancer

Leading cause of cancer death worldwide

Tobacco smoking

• Associated with the development of 80–90% of lung cancers

• The risk of cancer is determined by the number of pack years (quantity of cigarette packs a person smoked per day multiplied by the number of years of cigarette consumption)

• Weaker association with lung adenocarcinoma

Occupational and environmental exposure to carcinogens

• Passive smoking

• Radon (2nd leading cause of lung cancer) and uranium (radioactively decays into radon)

• Asbestos

• Occupational carcinogens (e.g., arsenic, chromium, nickel, beryllium, silica)

• Environmental air pollution

Family history (genetic predisposition)

Other risk factors: pulmonary scarring, previous radiation, pulmonary fibrosis, chronic infections (e.g., tuberculosis, HIV)

An apical lung carcinoma

Located in the superior sulcus of the lung (superior sulcus tumor)

Predominantly NSCLC

May lead to the development of Pancoast syndrome: a constellation of symptoms secondary to the mass effect of the tumor on surrounding structures

• Cervical sympathetic ganglion (stellate ganglion): Horner syndrome (ipsilateral miosis, ptosis, and anhidrosis)

• Brachial plexus

  • Localized pain in the axilla and shoulder (plexus neuralgia)

  • Upper limb motor and sensory deficits (e.g., hand muscle weakness and atrophy)

• Recurrent laryngeal nerve: hoarseness

• Brachiocephalic vein

  • Unilateral edema of the arm

  • Facial swelling

• Phrenic nerve: paralysis of the hemidiaphragm (visible as elevated hemidiaphragm on chest x-ray)