What is the purpose of the Ann Arbor staging system?

The Ann Arbor staging system is specifically designed for staging lymphomas, which are cancers that originate in the lymphatic system. This staging system classifies lymphomas based on the number and location of lymph nodes involved, as well as whether the disease has spread to other organs. The classification follows a set of criteria that determine the extent of disease, including whether it is localized to a particular region or if there is systemic involvement.

The stages range from Stage I, which indicates localized involvement, to Stage IV, where the disease has spread widely throughout the body. The system also includes designations for whether the lymphoma is accompanied by symptoms, known as 'B' symptoms, further refining the staging and providing essential information for treatment planning and prognostic evaluation.

In contrast, the other options focus on different types of cancers: breast cancer, melanoma, and lung cancer. Each of these has its own distinct staging systems and methods of assessment, making them unsuitable for the purpose defined by the Ann Arbor staging system.