  Background: The debate over daylight saving time has surged, with interests
in the effects of sunlight exposure on health. \commentnj{Prior studies
simulated daylight saving time and standard time conditions by analyzing
different locations within time zones and neighboring areas across time zone
borders.
  Methods: We analyzed cancer incidence rates from various longitudinal
positions within time zones and at time zone borders in the contiguous United
States. Using data from State Cancer Profiles (2016-2020), we analyzed total
cancer of 19 types and specific rates for eight cancers, adjusted for age and
includes all demographics. Log-linear regression is used to replicate a
previous study, and spatial regression models are employed to explore
discontinuities at borders.
  Results: Cancer rate differences lack statistical significance within time
zones and near borders for total cancer and most individual cancers. Exceptions
included breast, prostate, and liver \& bile duct cancers, which exhibited
significant relationships with relative position at the 95\% significance
level. Breast and liver and bile duct cancers saw decreases, while prostate
cancer incidence increased from west to east within time zones.
  Conclusions: Relative position does not have a significant impact on cancer
incidence, hence cancer development in general. Isolated exceptions may warrant
further investigation as more data becomes available.
  Impact: Our findings challenge prior research, revealing numerous
inconsistencies. These disparities urge a reconsideration of the potential
disparities in human health associated with daylight saving time and standard
time. They offer insights contribute to the ongoing discussion surrounding the
retention or abandonment of DST.
