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) biological profile (also called molecular profile, genetic 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).
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.
Click to watch a 1-minute video in which Dr. Cathy Pietanza of Memorial Sloan Kettering Cancer Center describes the differences between small cell and non-small cell lung cancer.
Other histologic types
Less common types of lung cancer include pleomorphic, carcinoid tumor, salivary gland carcinoma, and unclassified carcinoma.1
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 that may be found in lung cancer, and they are continuing to look for more. To date, there has been the most progress in understanding adenocarcinoma, but scientists are also learning about squamous cell and small cell mutations.2,3
See the Targeted Therapy section to read more about biomarker testing and different treatment options available for lung cancer with different kinds of genetic 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 two4
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.4
Updated February 23, 2016.
- Wistuba I, Brambilla E, Noguchi M. Chapter 17: Classic Anatomic Pathology and Lung Cancer. In: Pass HI, Ball D, Scagliotti GV, eds. The IASLC Multidisciplinary Approach to Thoracic Oncology. Aurora, CO: IASLC Press; 2014:217-240.
- Pao W, Ladanyi M. Detecting Gene Alterations in Cancers. My Cancer Genome website. http://www.mycancergenome.org/content/other/molecular-medicine/detecting-gene-alteations-in-cancers. Updated February 17, 2015. Accessed February 23, 2016.
- Lovly C, Horn L, Pao W. Molecular Profiling of Lung Cancer. My Cancer Genome website. Updated January 26, 2016. Accessed February 23, 2016.
- 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 February 23, 2016.