What are the stages and grades of lung cancer

How is lung cancer staged and graded?

Arabic numerals 0-4 describe stages of small cell lung cancer and Roman numerals I-IV for non-small cell lung cancer.

Stage 0: It is called carcinoma in situ, which means that the tumor is confined to the primary site, does not invade surrounding tissues, and has no extrapulmonary metastasis.

Stage I: The tumor is relatively small and has no lymph node metastasis, so it can be completely removed by surgery. According to the size of the tumor, it is divided into stage IA and stage IB. Smaller tumors are stage IA, and larger ones are stage IB.

Stage II: It can also be divided into two subtypes, stage IIA and stage IIB. There are two situations in stage IIA: one is that the tumor is slightly larger but there is no metastasis to the adjacent lymph nodes, and the other is a small tumor with metastasis to the surrounding lymph nodes. Stage IIB refers to large tumors and lymph node metastasis, or large tumors, or no surrounding lung structures, but no lymph node metastasis.

Stage III: It is divided into stage IIIA and stage IIIB. Many stage IIIA and almost all stage IIIB tumors are difficult or impossible to remove surgically. For example, the tumor involves the mediastinal lymph nodes, or the tumor invades adjacent structures within the lung. There is also a situation where the tumor cannot be completely removed due to various factors. In this case, it is difficult to completely remove the tumor.

Stage IV: This includes metastasis to multiple sites in the opposite lung, to the fluid around the lung or heart, or to other parts of the body through the bloodstream. Once cancer cells enter the bloodstream, they can spread to any part of the body, but more common sites of metastasis are the brain, bones, liver, and adrenal glands.