OBJECTIVES: Timely diagnosis is an important but understudied component of the cancer care continuum, particularly for cancers without screening programs. Existing diagnostic experience can provide insights to the design of diagnostic strategies accompanying novel screening tests. Guidelines recommend computed tomography (CT) scan as the initial imaging procedure for many abdominal cancers. We examined the association between the initial use of CT scan, time-to-diagnosis, and peri-diagnostic imaging use among Medicare beneficiaries diagnosed with pancreatic, bladder, liver, and ovarian cancers.

METHODS: Patients aged ≥65 years diagnosed with target cancers between 2010 and 2019 were identified from SEER-Medicare data. We examined the relationship between CT scan as the first imaging procedure and: (1) number of imaging tests from first imaging through treatment initiation; (2) days from first imaging test to diagnosis. We used negative binomial models to analyze count data, adjusting for sociodemographic and clinical characteristics.

RESULTS: A total of 169,781 patients (mean [SD] age: 76.6 [7.5]; 41.4% female) met inclusion criteria: 80,000 bladder, 48,751 pancreatic, 24,493 liver, and 16,537 ovarian patients. Overall, patients averaged 3.0 imaging tests (SD: 1.5) over 81 days (SD: 102). CT scan was the initial imaging test for 57% pancreatic, 54% liver, 62% ovarian, and 44% bladder cancer patients. CT scan vs. other initial tests was associated with shorter time to diagnosis (days,95%CI) (pancreatic: -29, (-31, -27); bladder: -29,(-31, -28); liver: -42,(-46, -38); ovarian: -38,(-42, -35)), and fewer imaging procedures (N,95%CI) (pancreatic: -0.7,(-0.8, -0.6); bladder: -0.2,(-0.3, -0.2); liver: -0.32,(-0.4, -0.2); and ovarian: -0.6,(-0.6, -0.5)).

CONCLUSIONS: Cancer patients aged ≥65 years with CT scan as their first imaging test experienced shorter time to diagnosis and fewer peri-diagnostic imaging procedures. CT scanning first offers an efficient imaging-based diagnostic resolution when an abdominal cancer is suspected clinically. This approach is worthy of evaluation in the setting of novel screening technologies like MCED.