What is the life expectancy of someone who has metastatic squamous cell carcinoma?

It depends. A low-grade squamous cell carcinoma of the mouth metastatic to one neck lymph node may get a cure. A low-grade lung cancer with bone metastases may kill in a few days by causing pneumonia, or be compatible with a few years' survival. In real life, no physician says, "you have thus-and-so long to live". I hope that you will cherish each day of life that you are given, living richly & loving well.
Statisics vs. n-of-1. Oncologists are good at giving prognostic life expectancy statistics for a population of patients with a specific cancer (with associated grade, stage, biomarkers, etc). However, we are not good (usually) at predicting the life expectancy of an individual patient. This is improving both in the the untreated patient (prognostic markers, etc) and after treatment but is still imperfect.

Related Questions

What would the life expectancy of someone with metastatic squamous cell carcinoma be?

Uncertain. It is notoriously difficult to predict the life span in a given patient, especially without knowing all of the person's medical history. Read more...

Is metastatic squamous cell carcinoma genetic?

No. Generally no. Usually environmental -- such as tobacco and scc lung cancer for instance. Read more...
Genetic component? There could be genetic component to a squamous cell cancer, although the exact implications on treatment aren't known. Obviously if there is a strong family history of cancers, or if it strikes someone who is young and/or a non smoker/drinker i would suspect a strong genetic contribution. Without more details, it is hard to say with any certainty. Read more...