There are three classification systems in use for categorizing the cancer stage. Although it does not contain the level of detail needed to support decisions on how to treat the disease, GSS is the system that has changed the least over the past twenty years. In situ cancers consist of malignant cells that have not penetrated the basement membrane of the tissue or organ in which they developed. Most in situ cancers are not included in the calculation of incidence rates. With the exception of bladder cancer, this is the only section of the report that contains information on in situ cancers in Minnesotans.
Localized cancers are tumors that are still contained within the organ in which they started.
Unknown stage cancers are those for which the information needed to determine stage was not available at the time of diagnosis. The distribution of stage at diagnosis varies widely among the various types of cancer. The distribution of stage at diagnosis was not relevant for four of the cancers in this Section. Similarly, since there is not a well-accepted staging scheme for brain cancers, the page for brain cancer displays the distribution of the morphologic or cell types of brain cancers. The MCSS estimates that ascertainment is between 95 and 97 percent.