Transportation-related factors, cancer screening, and stage at diagnosis: A scoping review.

BACKGROUND

Over 4 million Americans annually miss healthcare appointments - including for cancer screening and treatment - due to transportation insecurity. We performed a scoping review to understand how transportation affects cancer screening and stage at diagnosis, and to make recommendations for measuring transportation-related factors in this context.

METHODS

We searched PubMed, TRID, Embase, Scopus, and Web of Science for full-length, English-language, quantitative observational studies published from January 1, 2003 to June 12, 2025. We included observational studies on screening or stage measuring transportation barriers quantitatively at the patient level. Two authors reviewed content, extracted data, and assessed quality. We compared methods of measuring transportation-related factors and associations between these factors and screening/stage at diagnosis.

RESULTS

We screened 4567 abstracts, reviewed 446 full papers, and identified 53 screening and 43 stage at diagnosis studies after quality assessment. Transportation exposures were classified into travel distance/time, vehicle access, public transit, needing help to travel, patient perception of distance/time, and patient perception of transportation access. Travel distance/time accounted for 74% of analyses, and results were mixed between worse cancer outcomes for farther travelers (47%) and null or reversed results, but these findings were moderated by rurality and sociodemographic status. Owning a vehicle and being able to travel independently were associated with better clinical outcomes. Per quality assessment, papers were susceptible to referral and information bias; additionally, spatial auto-correlation and the hierarchical nature of data were frequently ignored leading to inflated effects.

CONCLUSIONS

Future research should go beyond "travel distance" to include alternative measures like vehicle ownership, car-less episodes, and needing help to travel to holistically evaluate transportation as a social driver of health.