===== Metastasis-Free Survival (MFS) =====

**[[Metastasis]]-Free [[Survival]] (MFS)** is a clinical trial endpoint that measures the length of time from the start of treatment (or randomization) until the development of **distant metastatic disease** or **death from any cause**, whichever occurs first.

==== Definition ====
  * MFS = Time from treatment initiation to:
    * First occurrence of **distant metastasis** (confirmed radiologically or pathologically), or
    * **Death from any cause**

==== Context of Use ====
  * Commonly used in:
    * **Prostate cancer** (especially non-metastatic castration-resistant prostate cancer, nmCRPC)
    * Other solid tumors where **distant spread** is the key determinant of prognosis
  * Serves as a **surrogate endpoint** for overall survival in certain trials.

==== Advantages ====
  * Focuses on clinically meaningful progression (distant metastasis).
  * Can provide **earlier readouts** than overall survival (OS).
  * Useful in settings with long survival times but high risk of distant spread.

==== Limitations ====
  * May not capture **local progression**.
  * Imaging frequency and sensitivity may affect detection.
  * Not always validated as a **true surrogate** for OS in all cancers.

==== Related Terms ====
  * [[Progression-Free Survival (PFS)]]
  * [[Overall Survival (OS)]]
  * [[Disease-Free Survival (DFS)]]
  * [[Distant Metastasis]]