About the Metastatic Prostate Cancer Prognosis Calculator
This calculator estimates PSA doubling time (PSADT), the standard exponential-growth measure of how fast a rising PSA is climbing between two blood tests. It then places that figure alongside two other well-recognized adverse prognostic markers in metastatic prostate cancer - ECOG performance status and the presence of visceral (liver or lung) metastases - to build a simple, transparent composite risk band.
How PSA doubling time is calculated
PSADT uses the standard formula for exponential doubling time: PSADT = t × ln(2) ÷ ln(PSA2 ÷ PSA1), where t is the number of months between the two tests, PSA1 is the earlier reading, and PSA2 is the later reading. Because the formula depends on the ratio of the two PSA values, it works in any consistent PSA unit as long as both readings use the same assay. If the later PSA is equal to or lower than the earlier one, there is no exponential growth to measure, and the calculator reports the trend as stable or falling instead of a doubling time.
Interpreting the kinetics band
Shorter doubling times are consistently associated with faster-growing, more aggressive disease in the published urologic-oncology literature, and thresholds near 3 months and 9 months are commonly used to separate rapid, high-risk, and intermediate kinetics from slower, more indolent trends. These are population-level associations built into commonly used clinical cutoffs, not a guarantee for any one person's disease course.
The composite risk category
The calculator adds one point for a short PSA doubling time band, one point for an ECOG performance status of 2 or higher, and one point for visceral metastases, then sums them into a lower, intermediate, high, or very high composite category. This is a transparent, rules-based composite for education and discussion - it is not the same as a validated multivariable survival nomogram, and it does not output a survival time or percentage.
When to consult a professional
This tool performs standard PSA-kinetics arithmetic and combines it with two established risk markers for education and record-keeping. It is not a diagnosis and does not direct treatment. Any decision about metastatic prostate cancer management should be made with a treating oncologist or urologist, who can weigh imaging, pathology, treatment history, and the full clinical picture.