Because prostate cancer generally grows slowly, it is not always appropriate to actively treat it once it is diagnosed. "Active surveillance" (also known as "watchful waiting") involves watching the PSA level - possibly having repeat biopsies - and beginning treatment when the cancer becomes more aggressive. This is a common method of treatment when a man is elderly, when a projected 10 to 15-year life span is not reasonable, or when the cancer appears to be clinically insignificant. For example, watchful waiting can be recommended to maintain the quality of life for a man with advanced heart disease who is not reasonably expected to live another 10 to 15 years.
However, active surveillance would not likely be recommended for a 50-year-old man who has been diagnosed with prostate cancer, but has a normal, active life and no prohibitive health problems. The grade of cancer needs to be taken into account as well, as a more aggressive type would be treated differently than a less-agressive type.