A primary care clinic on the frontline of early cancer detection: a retrospective observational study

Early cancer detection is critical. In Japan, the cancer detection system is diverse, encompassing cancer screenings, health checks, and comprehensive medical checkups (Ningen-dock). However, early detection pathways in primary care clinics remain unclear. This study aimed to investigate the current status of cancer detection and examine the clinical pathways leading to early diagnosis in a primay care clinic.

A retrospective observational study was conducted among cancer cases detected at a single primary care clinic in Japan between April 2009 and March 2023. In total, 17,942 patient charts were reviewed, representing 267,313 individual consultations during the study period. Data collected included cancer type, number, age, sex, smoking, comorbidities, detection pathways, and whether the cancer was early (without distant metastasis) or advanced (with distant metastasis). Multivariable logistic regression was performed to assess the associations between early cancer and both the detection pathways and follow-up by primary care physician. Univariate analyses were performed to evaluate associations between detection pathways and early cancer detection by cancer types.

Three hundred forty-seven cases (29 types) were identified, comprising 283 early and 64 advanced. Early cancers had significantly higher detection rates through health screening-related, incidental or follow-up by primary care pathways (p < 0.05), whereas symptomatic detection was significantly less frequent (p < 0.05). For gastrointestinal and respiratory cancers, early detection was significantly associated with health screening-related (p < 0.05), whereas symptomatic detection predominated in advanced (p < 0.05). In hepatobiliary pancreatic, urinary, and other cancers, no significant differences were observed between early and advanced cancers in health screening-related; detection was mostly symptomatic.

Cancer screening, health checks, comprehensive medical checkups, asymptomatic examinations, and follow-up by primary care physician might be associated with early cancer detection. However, certain cancer types presented difficulties for early detection. Studies discussing the overall picture of early cancer detection using real-world data from primary care clinics remain limited, and the findings of this study are expected to contribute to building a foundation for secondary prevention policies.