By stage

At diagnosis, cancer can be just a small, hardly visible alteration or cancer can spread to adjacent tissues, lymph nodes or to distant organs. The extent of disease doctors classify in several stages according to different systems, most often according to TNM classification (T for tumor, N for lymph node and M for metastasis). In this classification, the stage is based on the size of the tumor (T1 to T4) and whether the cancer has spread to lymph nodes(N1 or N0) or other parts of the body (M1 or M0).

A simplified definition of stages is generally used for stage classification by cancer registries: localised, regional and remote.

In solid tumors, the simplified stage definition generally follows the TNM classification.

Localised stageincludes all cancers where the tumour has been classified as T1 and T2 (except in breast, malignant melanoma and thyroid cancer, where T3 is also included, and uterine cervix, uterine corpus and sarcomas, where T1 only is included), where neither regional node involvement nor distant metastases are found (N0, M0).

The regional stage includes tumours classified as T3 and T4 (exceptions already mentioned) and/or regional node metastases (N1), without presence of metastases in distant lymph nodes or organs (M0).

The disease with metastases in distant lymph nodes or organs is classified as the remote stage (M1).

Malignant lymphomas are classified according to Ann-Arbor System.