Give a stream of consciousness and then the final answer. The War on Cancer refers to the effort to find a cure for cancer by increased research to improve the understanding of cancer biology and the development of more effective cancer treatments, such as targeted drug therapies. The aim of such efforts is to eradicate cancer as a major cause of death. The signing of the National Cancer Act of 1971 by United States president Richard Nixon is generally viewed as the beginning of this effort, though it was not described as a "war" in the legislation itself.

Answer this question: when did the united states declare a war on cancer by passing the national cancer act?

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
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This is the relevant information: The signing of the National Cancer Act of 1971 by United States president Richard Nixon is generally viewed as the beginning of this effort, though it was not described as a "war" in the legislation itself.
So, the final answer is 1971.