Lung cancer describes many different types of cancer that start in the lung or related structures.
There are two different ways of describing what kind of lung cancer a person has: (1) histology—what the cells look like under a microscope; and (2) biomarker profile (also called molecular profile, genomic profile, or signature profile)—the kinds of A biological molecule found in blood, other body fluids, or tissues that is a sign of a normal or abnormal process, or of a condition or disease found in the tissue.
Because each type of lung cancer behaves and is treated differently, it helps to have as much information as possible about a person’s individual lung cancer. To get that information, a surgeon should provide samples of the tumor from a The removal of cells or tissues for examination by a pathologist to a A doctor who identifies diseases by studying cells and tissues under a microscope or with other equipment. Having a pathologist who is experienced in looking at lung cancer will provide the most accurate information.
Classification by histology
The different types of lung cancer are described histologically by the types of cells the pathologist sees under the microscope. About 15% of lung cancers are small cell lung cancer (SCLC), while about 85% are non-small cell lung cancer (NSCLC).1
There are three major types of non-small cell lung cancer:
More information on each of these types is available on separate pages on this website.
Other histologic types
Less common types of lung cancer include sarcomatoid carcinoma, salivary gland tumor, and unclassified carcinomas.2
Classification by biomarker profile
Lung cancer is a complex disease that not only is classified by cell type, but also can be divided further by mutation—the changes to the cell that allowed the cancer to grow. Each type of lung cancer may or may not have one of the mutations. So far, researchers have identified a number of different mutations, called driver mutations, that can lead to lung cancer, and they are continuing to look for more. To date, there has been the most progress in understanding adenocarcinoma driver mutations, but scientists are also learning about squamous cell and small cell driver mutations.3,4,5,6
See the Targeted Therapy section to read more about biomarker testing and different treatment options available for lung cancer based on the presence of specific driver mutations.
Other ways to describe a tumor
Other ways a pathologist might describe a tumor are by:
How fast it is likely to grow and spread
These terms are based on how it looks under a microscope:
- Well-differentiated: tending to grow more slowly
- Poorly differentiated: most aggressive tumor
- Moderately differentiated: growth speed is in-between the other two7
If the entire tumor is removed, the pathologist will measure it by just looking at it or, if it is very small, by measuring it under the microscope. Usually, what is reported is how big it is across at the point where the tumor is the largest. For biopsies the pathologist receives only part of a tumor, so the size of the tumor is not usually reported.7
Updated January 3, 2018
- What is Non-Small Cell Lung Cancer? American Cancer Society website. https://www.cancer.org/cancer/non-small-cell-lung-cancer/about/what-is-non-small-cell-lung-cancer.html. Revised May 16, 2016. Accessed December 12, 2017.
- Wistuba I, Brambilla E, Noguchi M. Chapter 17: Classic Anatomic Pathology and Lung Cancer. In: Pass HI, Ball D, Scagliotti GV, eds. IASLC Thoracic Oncology, Second Edition. Philadelphia, PA: Elsevier; 2018:143-146.
- Hirsch FR, Suda K, Wiens J, Bunn PA, Jr. New and emerging targeted treatments in advanced non-small-cell lung cancer. Lancet. Sep 3 2016: 388(10048): 1012-1024. http://www.thelancet.com/pdfs/journals/lancet/PIIS0140-6736(16)31473-8.pdf. Accessed December 12, 2017.
- Cancer Genome Atlas Research Network. Comprehensive genomic characterizations of squamous cell lung cancers. Nature. Sep 27 2012; 489(7417); 519-525. https://www.nature.com/articles/nature11404. Accessed December 12, 2017.
- Paik PK, Shen R, Won H, et al. Next-Generation Sequencing of Stage IV Squamous Cell Lung Cancers Reveals an Association of P13K Aberrations and Evidence of Clonal Heterogeneity in Patients with Brain Metastases. Cancer Discovery. Jun 2015: 5(6): 610-621. https://www.ncbi.nlm.nih.gov/pubmed/25929848. Accessed December 12, 2017.
- Perez-Moreno P, Brambilla E, Thomas R, Soria JC. Squamous cell carcinoma of the lung: molecular subtypes and therapeutic opportunities. Clinical cancer research: an official journal of the American Association for Cancer Research. May 01 2012; 18(9):2443-2351. http://clincancerres.aacrjournals.org/content/18/9/2443.long. Accessed December 12, 2017.
- Lung Cancer: Understanding Your Pathology Report: Fact Sheet. Association of Directors of Anatomic and Surgical Pathology website. http://www.adasp.org/FAQs/02-lung.html. Accessed December 12, 2017.