You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
John_von_Neumann

Context:
In 1955, von Neumann was diagnosed with what was either bone or pancreatic cancer. His mother, Margaret von Neumann, was diagnosed with cancer in 1956 and died within two weeks. John had eighteen months from diagnosis till death. In this period von Neumann returned to the Roman Catholic faith that had also been significant to his mother after the family's conversion in 1929–1930. John had earlier said to his mother, "There is probably a God. Many things are easier to explain if there is than if there isn't." Von Neumann held on to his exemplary knowledge of Latin and quoted to a deathbed visitor the declamation "Judex ergo cum sedebit," and ends "Quid sum miser tunc dicturus? Quem patronum rogaturus, Cum vix iustus sit securus?" (When the judge His seat hath taken ... What shall wretched I then plead? Who for me shall intercede when the righteous scarce is freed?)

Question:
How long did von Neumann survive with cancer?

eighteen months