Lung cancer: Clinical

To be retired ⓘ

00:00 / 00:00



Lung cancer: Clinical

USMLE® Step 2 questions

0 / 16 complete


USMLE® Step 2 style questions USMLE

of complete

A 60-year-old man comes to the office because of a 6-month history of cough, dyspnea, and muscle weakness. The weakness is worst when he is resting and improves after he has walked around. He has smoked one pack of cigarettes daily for 40 years. An x-ray of the chest shows flattening of the diaphragm and elongation of the mediastinum as well as a 2-cm nodule near the hilum. Which of the following is the most likely diagnosis?


Lung cancer is the leading cause of cancer death worldwide in both males and females. It’s broadly classified into non-small cell lung cancer; accounting for 85% of all lung cancers, and small cell lung cancer, accounting for the remaining 15%.

Small cell lung cancers are centrally located in the lung. Non-small cell lung cancer is further subclassified into four subtypes, the most common one is adenocarcinoma, which usually develops at the periphery of the lung. There’s also the term bronchoalveolar carcinoma which refers to adenocarcinoma-in-situ, which is where the adenocarcinoma tumor isn’t quite as aggressive and hasn’t yet crossed the basement membrane. The other 3 subtypes of non-small cell cancer include squamous cell carcinoma and carcinoid tumors; which are usually centrally located, as well as the rare large cell carcinoma; which can be located either centrally or peripherally.

Now the most important risk factor for the development of lung cancer is tobacco smoking, which accounts for more than 90% of cases. This usually comes in the form of cigarettes, but also includes cigars, pipes, and hookah, also called shisha. There is a dose-dependent linear relationship between the pack-years - the number of cigarette packs per day times the number of years of smoking - and the risk of lung cancer. Second-hand smoking, which is involuntarily inhaling tobacco smoked by other people, also increases the risk of lung cancer.

Additionally individuals exposed to asbestos for a long period of time such as those working in shipbuilding or construction industry, are also at increased risk. Although classically associated with mesothelioma, which is a malignancy of the pleura, asbestos more commonly causes adenocarcinoma. Other risk factors include radon exposure, which is found in high concentrations in basements, as well as exposure of chest radiation, such as in treatment of lymphoma.


  1. "Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2)" McGraw-Hill Education / Medical (2018)
  2. "Pathophysiology of Disease: An Introduction to Clinical Medicine 8E" McGraw-Hill Education / Medical (2018)
  3. "CURRENT Medical Diagnosis and Treatment 2020" McGraw-Hill Education / Medical (2019)
  4. "Robbins Basic Pathology" Elsevier (2017)
  5. "Yen & Jaffe's Reproductive Endocrinology" Saunders W.B. (2018)
  6. "Bates' Guide to Physical Examination and History Taking" LWW (2017)
  7. "Small cell lung cancer" Annals of Oncology (2006)
  8. "American Cancer Society lung cancer screening guidelines" CA: A Cancer Journal for Clinicians (2013)
  9. "Reduced Lung-Cancer Mortality with Volume CT Screening in a Randomized Trial" New England Journal of Medicine (2020)
  10. "Reduced Lung-Cancer Mortality with Low-Dose Computed Tomographic Screening" New England Journal of Medicine (2011)

Copyright © 2023 Elsevier, its licensors, and contributors. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Cookies are used by this site.

USMLE® is a joint program of the Federation of State Medical Boards (FSMB) and the National Board of Medical Examiners (NBME). COMLEX-USA® is a registered trademark of The National Board of Osteopathic Medical Examiners, Inc. NCLEX-RN® is a registered trademark of the National Council of State Boards of Nursing, Inc. Test names and other trademarks are the property of the respective trademark holders. None of the trademark holders are endorsed by nor affiliated with Osmosis or this website.