The calculator in question is the TNM Classification for Perihilar Cholangiocarcinoma. TNM stands for Tumor, Node, Metastasis, and it is a globally recognized system used for classifying the extent of spread of cancer. 

This specific TNM classification is applicable to patients diagnosed with perihilar cholangiocarcinoma, a type of cancer that occurs in the bile ducts near the liver. The TNM classification helps in staging the disease, which is crucial for determining the most appropriate treatment strategy and predicting patient prognosis.

The clinical utility of this calculator lies in its ability to provide a standardized method for assessing the severity of perihilar cholangiocarcinoma. It takes into account the size and extent of the primary tumor (T), whether the cancer has spread to nearby lymph nodes (N), and the presence of distant metastasis (M).

There are no specific exclusion criteria for the use of the TNM Classification for Perihilar Cholangiocarcinoma. However, it is not applicable to patients with other types of cancer or those who have not been definitively diagnosed with perihilar cholangiocarcinoma.

TNM classification for perihilar cholangiocarcinoma

# Criteria
 ## Tumor classification
A. Tx: Primary tumor cannot be assessed
B. T0: No evidence of primary tumor
C. Tis: Carcinoma in situ/high-grade dysplasia
D. T1: Tumor confined to bile duct with extension up to muscle layer or fibrous tissue
E. T2a: Tumor invading beyond wall of bile duct to surrounding adipose tissue
F. T2b: Tumor invading adjacent hepatic parenchyma
G. T3: Tumor invading unilateral branches of portal vein or hepatic artery
H. T4: Tumor invading any of following: main portal vein or its branches bilaterally, or common hepatic artery; unilateral second-order biliary radicals with contralateral portal vein or hepatic artery involvement
## Lymph node classification
I. Nx: Regional lymph nodes cannot be assessed
J. N0: No regional lymph node metastasis
K. N1: 1-3 positive lymph nodes typically involving hilar, cystic duct, common bile duct, hepatic artery, posterior pancreatoduodenal, and portal vein lymph nodes
L. N2: >= 4 positive lymph nodes from sites described for N1
## Metastasis classification
M. M0: No distant metastasis
N. M1: Distant metastasis present

# Conditions
- C and J and M
- D and J and M
- (E or F) and J and M
- G and J and M
- H and J and M
- (C or D or E or F or G or H) and K and M
- (C or D or E or F or G or H) and L and M
- (C or D or E or F or G or H) and (I or J or K or L) and N
- true