Which source represents a secondary casefinding source?

The correct choice for a secondary casefinding source is identified as surgery schedules for seed implants. Secondary casefinding sources are used to identify patients who may not be included in primary data collections and often come from processes or documentation related to the treatment and management of cancer patients, rather than initial diagnoses or treatment records.

Surgery schedules for seed implants specifically allow oncology data specialists to recognize additional cases of cancer treatment that may not be immediately evident through direct pathological diagnosis alone. These schedules can highlight various treatment interventions performed on patients, contributing additional relevant data to cancer registries.

The other options primarily serve as primary casefinding sources. Pathology reports are fundamental in confirming the diagnosis of cancer at the outset of care, while radiation oncology logs and medical oncology treatment summaries gather information about the ongoing treatment that patients receive, reflecting either diagnostic or treatment-related activities rather than secondary identification.