rare cancer

Definition of rare cancer
National Cancer Institute

rare cancer

(rayr KAN-ser)
As defined by the National Cancer Institute, cancer that occurs in fewer than 15 out of 100,000 people each year. Most types of cancer are considered rare, and they are often more difficult to prevent, diagnose, and treat than the more common cancers. Because there are fewer cases, research is difficult. Examples of rare cancers are anal, stomach, and laryngeal cancer.

Source: NCI Dictionary of Cancer Terms