The list of common cancers includes cancers that are diagnosed with the greatest frequency in the United States. Cancer incidence statistics from the American Cancer Society and other resources were used to create the list. To qualify as a common cancer, the estimated annual incidence for 2006 had to be 30,000 cases or more.

The most common type of cancer on the list is non-melanoma skin cancer, with more than 1,000,000 new cases expected in the United States in 2006. Non-melanoma skin cancers represent about half of all cancers diagnosed in this country.

The cancer on the list with the lowest incidence is thyroid cancer. The estimated number of new cases of thyroid cancer for 2006 is 30,180.

Because colon and rectal cancers are often referred to as "colorectal cancers," these two cancer types were combined for the list. For 2006, the estimated number of new cases of colon cancer is 106,680, and the estimated number of new cases of rectal cancer is 41,930. These numbers are slightly larger than those estimated for 2005.

Kidney cancers can be divided into two major groups, renal parenchyma cancers and renal pelvis cancers. Approximately 82 percent of kidney cancers develop in the renal parenchyma, and nearly all of these cancers are renal cell cancers. The estimated number of new cases of renal cell cancer for 2006 is 31,890.

Leukemia as a cancer type includes acute lymphoblastic (or lymphoid) leukemia, chronic lymphocytic leukemia, acute myeloid leukemia, chronic myelogenous (or myeloid) leukemia, and other forms of leukemia. It is estimated that more than 35,000 new cases of leukemia will be diagnosed in the United States in 2006, with acute myeloid leukemia being the most common type (approximately 12,000 new cases). The total number of new leukemia cases estimated for 2006 is slightly larger than the number estimated for 2005.