Observed survival is an estimate of the probability of surviving all causes of death.

• A. False
• B. True
• C. It estimates cancer-specific survival
• D. It estimates conditional survival

Answer: (B)

Observed (overall) survival is the probability of being alive at a defined follow-up time, counting deaths from any cause. That means it estimates survival from all causes of death, not just cancer. It differs from cancer-specific survival, which isolates deaths caused by cancer and treats other causes as non-events or competing risks. It also isn’t the same as conditional survival, which asks the chance of surviving additional time given you have already survived a certain period. So this statement is true: observed survival reflects survival from all causes.