BACKGROUND

Although previous studies have observed the relationship between living in persistent poverty areas (PPAs) and adverse cancer outcomes, the relationship between residing in PPAs and disparities in cancer incidence rates and temporal trends by race/ethnicity and sex in California is unknown.

METHODS

We used California Cancer Registry data to identify patients diagnosed with 16 common cancers between 2006 and 2020. We calculated age-adjusted incidence rates (IRs), incidence rate ratios (IRRs), and average annual percent changes (AAPCs) to compare incidence and temporal trends in PPAs and non-PPAs in California by race/ethnicity and sex. PPA was defined as areas with a poverty rate of 20% or more for approximately 30 continuous years.

RESULTS

Male patients in PPAs had significantly higher IRRs of colorectal, liver, lung, and stomach cancers, and female patients had higher cervical, kidney, liver, and stomach cancers. Across all racial/ethnic groups, cervical and liver cancer IRRs were significantly higher, and IRRs for female breast cancer were lower in PPAs. The incidence of several cancers significantly decreased over time only in non-PPAs. Colorectal cancer and non-Hodgkin lymphoma among Hispanic residents significantly increased in PPAs (AAPC = 0.4, 1.2) and colorectal cancer decreased only in non-PPAs (AAPC = -1.4). Thyroid cancer among non-Hispanic Black residents increased only in PPAs (AAPC = 4.7).

CONCLUSION

Our findings highlight race/ethnicity and sex disparities in cancer incidence and temporal trends for PPA residents. Further research is needed to understand the specific etiological factors underlying these disparities, and to support the development of public health policies and initiatives to decrease the cancer burden in California.