The calculator in question is the TNM Classification for Parathyroid Carcinoma, also known as the Shaha Staging System. This calculator is used specifically for patients diagnosed with parathyroid carcinoma, a rare type of endocrine cancer. 

The clinical utility of this calculator is to stage the severity of the parathyroid carcinoma, which is crucial for determining the appropriate treatment plan and predicting the patient's prognosis. The TNM Classification for Parathyroid Carcinoma takes into account the size of the tumor (T), whether the cancer has spread to the lymph nodes (N), and whether the cancer has metastasized to other parts of the body (M). 

There are no specific exclusion criteria for the use of this calculator. However, it is not applicable to patients with other types of cancer or those who have not been definitively diagnosed with parathyroid carcinoma.

TNM classification for parathyroid carcinoma (Shaha system)

# Description:
The calculator in question is the TNM Classification for Parathyroid Carcinoma, also known as the Shaha Staging System. This calculator is used specifically for patients diagnosed with parathyroid carcinoma, a rare type of endocrine cancer. 

The clinical utility of this calculator is to stage the severity of the parathyroid carcinoma, which is crucial for determining the appropriate treatment plan and predicting the patient's prognosis. The TNM Classification for Parathyroid Carcinoma takes into account the size of the tumor (T), whether the cancer has spread to the lymph nodes (N), and whether the cancer has metastasized to other parts of the body (M). 

There are no specific exclusion criteria for the use of this calculator. However, it is not applicable to patients with other types of cancer or those who have not been definitively diagnosed with parathyroid carcinoma.
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# Inputs:
## Tumor classification
A. Tx: Primary tumor cannot be assessed
B. T1. Tumor < 3 cm
C. T2: Tumor > 3 cm
D. T3: Tumor of any size invading surrounding soft tissues (thyroid gland, infrahyoid muscles)
E. T4: Massive central compartment disease invading trachea and esophagus or recurrent parathyroid cancer

## Lymph node classification
F. Nx: Regional lymph nodes cannot be assessed
G. N0: No regional lymph node metastasis
H. N1: Regional lymph node metastasis present

## Metastasis classification
I. M0: No distant metastasis
J. M1: Distant metastasis present
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# Scoring:
- If B and G and I, then Stage I
- If C and G and I, then Stage II
- If D and G and I, then Stage IIIa
- If E and G and I, then Stage IIIb
- If (B or C or D or E) and H and I, then Stage IIIc
- If (B or C or D or E) and (G or H) and J, then Stage IV
- If true, then Stage cannot be fully assessed)