Which of the following is a standard pair of survival measures?

• A. Observed survival
• B. Net survival
• C. Observed survival and net survival
• D. Both observed survival and disease-specific survival

Answer: (C)

Two commonly used survival measures in cancer prognosis are observed (overall) survival and net survival. Observed survival tracks how many patients are alive after a set time, regardless of cause of death, so it reflects real-world outcomes. Net survival estimates survival as if cancer were the only possible cause of death, removing the influence of other mortality causes by comparing to expected survival from the general population. These two together form a standard pair because they give complementary views: observed survival shows actual experience, while net survival isolates the effect of cancer itself, allowing fair comparisons across populations with different background mortality. The other options don’t form that standard pairing: disease-specific survival depends on accurate cause-of-death data and isn’t typically paired with observed survival in the same standard way, and using just one measure doesn’t provide the dual perspective that the standard pair offers.