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A period survival analysis estimates survival under the recent mortality conditions operating during a fixed calendar period. For calendar year 2022, each cancer patient's contribution begins at the later of diagnosis and 1 January 2022, which treats earlier diagnoses as left-truncated at the start of the year. Follow-up ends at death, loss to follow-up, or 31 December 2022, so surviving records are right-censored. Combining these risk-set contributions, commonly through a Kaplan–Meier estimator, constructs the 2022 period survivor function; records from several diagnosis cohorts may contribute different segments of follow-up.