The Nottingham prognostic index (NPI) is used to determine prognosis following surgery for breast cancer. Its value is calculated using three pathological criteria: the size of the tumour; the number of involved lymph nodes; and the grade of the tumour. It is calculated to select patients for adjuvant treatment.
Calculation
The index is calculated using the formula:
NPI = [0.2 x S] + N + G
Where:
S is the size of the index lesion in centimetres N is the node status: 0 nodes = 1, 1-3 nodes = 2, >3 nodes = 3 G is the grade of tumour: Grade I =1, Grade II =2, Grade III =3
Interpretation Score 5-year survival >/=2.0 to </=2.4 93% >2.4 to </=3.4 85% >3.4 to </=5.4 70% >5.4 50%
References
External links Online calculator based on Todd et al, 1987 study The Nottingham Prognostic Index Biomedical Informatics Research Group