Breast Cancer Recurrence Risk Calculator
This calculator uses the Nottingham Prognostic Index (NPI), a clinically validated scoring tool used by oncologists to estimate prognosis in early invasive breast cancer. Enter your tumour size, lymph node stage, and histological grade to get your NPI score, risk group, and estimated 5-year and 10-year survival rates. Results are for educational use only and must be interpreted with your oncology team.
Formula
Worked example
A 2.5 cm tumour, 2 positive lymph nodes (node stage 2), grade 2: NPI = (0.2 x 2.5) + 2 + 2 = 0.5 + 2 + 2 = 4.5, placing the patient in the Moderate II group with an estimated 5-year survival of about 85%.
What is the Nottingham Prognostic Index?
The Nottingham Prognostic Index (NPI) is a validated scoring formula developed at Nottingham City Hospital in the 1980s and published by Galea et al. in 1992. It combines three pathological factors - tumour size, the number of cancerous lymph nodes, and histological grade - into a single number that stratifies patients into five prognostic groups from Excellent to Poor. Each group carries a distinct estimated survival rate, giving oncologists a reproducible, cost-effective way to assess prognosis and guide adjuvant treatment decisions in early invasive breast cancer. The NPI has been validated in multiple independent cohorts and is widely used in the United Kingdom and internationally as part of routine breast cancer assessment.
How is the NPI calculated?
The formula is: NPI = (0.2 x tumour size in centimetres) + lymph node stage score + histological grade score. Tumour size is the maximum invasive diameter measured by the pathologist. The lymph node stage score is 1 for no positive axillary nodes (pN0), 2 for 1 to 3 positive nodes (pN1), and 3 for 4 or more positive nodes (pN2/pN3). The histological grade (Elston-Ellis or Nottingham grade) scores 1 for well-differentiated (Grade 1), 2 for moderately differentiated (Grade 2), and 3 for poorly differentiated (Grade 3). For example, a 2.5 cm tumour with 1 positive node and Grade 2 histology gives NPI = (0.2 x 2.5) + 2 + 2 = 4.5, which falls in the Moderate II group. All three values come directly from the pathology report you receive after surgery.
Understanding the five NPI prognostic groups
Scores up to 2.4 are in the Excellent Prognostic Group (EPG), associated with approximately 97% 5-year survival and 89% 10-year survival. Scores from 2.41 to 3.4 are the Good Prognostic Group (GPG) with around 93% and 84% respectively. Moderate I (MPG1, scores 3.41 to 4.4) corresponds to about 90% and 77%. Moderate II (MPG2, scores 4.41 to 5.4) corresponds to about 85% and 70%. Scores above 5.4 are in the Poor Prognostic Group (PPG) with about 75% 5-year and 55% 10-year survival. These figures come from a screened population study and represent all-cause survival, not breast-cancer-specific survival, so they include deaths from other causes. Individual outcomes depend heavily on additional factors including receptor status and systemic treatment received.
NPI alongside other prognostic tools
The NPI is one of several complementary tools oncologists use to plan treatment. It captures morphological features well but does not account for hormone receptor status (ER, PR), HER2 amplification, or genomic risk scores such as Oncotype DX or Mammaprint, all of which carry independent prognostic value. Lymphovascular invasion (LVI) - whether cancer cells have infiltrated lymphatic or blood vessels near the tumour - is another significant prognostic factor not included in the original NPI formula. Some centres use the NPI+ framework, which incorporates additional biological subtypes. Your oncologist will integrate NPI results with your full pathology report, genomic testing where available, your age, menopausal status, and comorbidities when recommending adjuvant therapy.
NPI prognostic groups and survival estimates
| NPI score | Group | 5-year survival | 10-year survival | Risk level |
|---|---|---|---|---|
| 2.0 to 2.4 | Excellent (EPG) | 97% | 89% | Very low |
| 2.41 to 3.4 | Good (GPG) | 93% | 84% | Low |
| 3.41 to 4.4 | Moderate I (MPG1) | 90% | 77% | Intermediate |
| 4.41 to 5.4 | Moderate II (MPG2) | 85% | 70% | Higher intermediate |
| Above 5.4 | Poor (PPG) | 75% | 55% | High |
All-cause survival data from a screened breast cancer population (Rakha et al. 2014, Annals of the Royal College of Surgeons of England). Figures are population estimates for each NPI group, not individual predictions.
Frequently asked questions
Where do I find the values needed for the NPI calculator?
All three values come from your pathology report, the document produced by the pathologist after examining tissue removed during your surgery. Tumour size is the maximum invasive diameter. The nodal stage is based on how many axillary lymph nodes contained cancer cells. Histological grade (Grade 1, 2, or 3) is assigned by the pathologist based on how the cancer cells look under a microscope. If you are unsure, ask your breast care nurse or surgeon to go through the report with you.
Is a lower or higher NPI score better?
Lower is better. A score of 2.0 to 2.4 is in the Excellent group with the most favourable prognosis. Scores above 5.4 fall in the Poor group and indicate a higher risk of recurrence and poorer long-term survival. The minimum theoretically possible NPI is around 2.02 (a very small tumour, no nodes, Grade 1), and the maximum is around 8 (a large tumour with extensive nodal disease, Grade 3).
Does the NPI predict whether my breast cancer will come back?
The NPI estimates the statistical likelihood of recurrence and survival for a group of patients with the same score, not a certainty for any individual. A patient in the Poor group may have an excellent outcome, and a patient in the Excellent group can still experience recurrence. The index is a tool to guide treatment decisions about adjuvant chemotherapy, hormonal therapy, and radiotherapy, not a definitive forecast for any single person.
Is the NPI the same as the Oncotype DX score?
No. The NPI uses three pathological features that are routinely available from standard surgery. Oncotype DX is a genomic assay that analyses the activity of 21 genes in the tumour tissue and is used specifically for early-stage hormone receptor-positive, HER2-negative breast cancer to estimate the benefit of chemotherapy. Both provide complementary prognostic information and many oncologists use them together for decision-making in eligible patients.
What does lymphovascular invasion mean for my prognosis?
Lymphovascular invasion (LVI) means cancer cells have been found inside lymphatic or blood vessels near the primary tumour. It is a well-established independent adverse prognostic factor, particularly in node-negative patients, and is associated with a higher risk of local and distant recurrence. LVI is not part of the original NPI formula, but this calculator shows it alongside your NPI score so your full set of pathological risk factors is visible at a glance.
Can I use this calculator if I have had neoadjuvant chemotherapy before surgery?
The original NPI was developed for tumours assessed at primary surgery, before any systemic treatment. If you received chemotherapy before surgery (neoadjuvant chemotherapy), the pathological features of the remaining tumour may not reflect the original biology. In that situation, post-treatment pathological complete response (pCR) or residual cancer burden (RCB) are typically used to assess prognosis instead. Discuss the most appropriate tool for your situation with your oncologist.