Bile duct cancer is separated into four phases: Phase I involves carcinoma in-situ where cancer is non-invasive and located only in the inner layer of the bile duct. Phase II cancer has invaded surrounding organs or lymph nodes and is split into Stage IIA and IIB. Phase III cancer is split into Stage IIIA, where nearby lymph nodes may contain cancer, and Stage IIIB, where the primary blood vessels may be affected but remote organs are still cancer-free. Phase IV cancer has spread to distant organs.

1. Bile Duct Cancer Phases
Phase I
Stage II
The first phase of bile duct cancer is carcinoma in-situ, or Period 0, which is cancer that is non-
invasive. In this phase, according to the American Cancer Society, the cancer is in the bile duct's
inner most layer, known as the mucosa. It's not in other organs or any lymph nodes.
Period III
Stage I bile duct cancer involves one tumour that's started
to invade into more levels of the wall of the bile duct like
the muscle layer, but has not attained any blood vessels.
Phase IV
Phase two cancer is separated by the National Cancer
Institute into phase IIA and IIB. Stage IIA bile duct cancer is
when the cancer has invaded gallbladder, the liver, pancreas and either aspect of the hepatic artery
or portal vein. Period IIB affects the liver, gall bladder, or cancer which has spread to lymph nodes
that are adjacent, in addition to both the bile duct, the wall, pancreas, or both aspect of the hepatic
artery or portal vein.
Phase III bile duct cancer is split into two sub -phases, Stage IIIA and IIIB. Lymph glands and other
organs are cancer-free. Cancer may take the primary blood vessels. Remote organs aren't malignant,
although lymph nodes that are nearby may possibly have cancer in them. In accordance with the
National Cancer Institute, cancer which has spread to nearby organs such as the colon, stomach,
small bowel or abdominal wall may be also included by Stage III cancer.