Eyes Wide Open: Sleep as a Potential Contributor to Racial and Ethnic Disparities in Cancer

U.S. racial and ethnic minoritized groups face disproportionate cancer burdens compared to White Americans. Investigating modifiable factors, such as sleep, that are socially patterned and inequitably distributed by race and ethnicity may advance understanding of cancer disparities and provide intervention opportunities. Emerging data suggest poor sleep health is associated with cancer. Yet, its contribution to racial and ethnic cancer disparities is understudied. In this narrative review, we explored the sleep-cancer relation through a disparities lens. We (i) summarized literature reporting on associations between sleep and cancer among racial and ethnic minority populations; (ii) examined potential sleep-cancer mechanisms; and (iii) discussed future directions. We identified five studies reporting on sleep-cancer associations among minoritized groups. Poor sleep health was associated with aggressive breast cancer among Black women, increased breast cancer risk among Asian women, and increased risk of breast and total cancer among Hispanic/Latinx Americans. Sleep and cancer disparities have similar socioeconomic and behavioral determinants, suggesting racial and ethnic minoritized groups may be vulnerable to poor sleep health and its adverse health impacts. Evidence indicates that the sleep-cancer disparities relation is an emerging, but important area of research that warrants further investigation, as sleep may be an avenue for reducing cancer disparities.

Historical Redlining, Persistent Mortgage Discrimination, and Race in Breast Cancer Outcomes

Importance

Inequities created by historical and contemporary mortgage discriminatory policies have implications for health disparities. The role of persistent mortgage discrimination (PMD) in breast cancer (BC) outcomes has not been studied.

Objective

To estimate the race-specific association of historical redlining (HRL) with the development of BC subtypes and late-stage disease and a novel measure of PMD in BC mortality.

Design, Setting, and Participants

This population-based cohort study used Georgia Cancer Registry data. A total of 1764 non-Hispanic Black and White women with a BC diagnosis and residing in an area graded by the Home Owners' Loan Corporation (HOLC) in Georgia were included. Patients were excluded if they did not have a known subtype or a derived American Joint Committee on Cancer stage or if diagnosed solely by death certificate or autopsy. Participants were diagnosed with a first primary BC between January 1, 2010, to December 31, 2017, and were followed through December 31, 2019. Data were analyzed between May 1, 2022, and August 31, 2023.

Exposures

Scores for HRL were examined dichotomously as less than 2.5 (ie, nonredlined) vs 2.5 or greater (ie, redlined). Contemporary mortgage discrimination (CMD) scores were calculated, and PMD index was created using the combination of HRL and CMD scores.

Main Outcomes and Measures

Estrogen receptor (ER) status, late stage at diagnosis, and BC-specific death.

Results

This study included 1764 women diagnosed with BC within census tracts that were HOLC graded in Georgia. Of these, 856 women (48.5%) were non-Hispanic Black and 908 (51.5%) were non-Hispanic White; 1148 (65.1%) were diagnosed at 55 years or older; 538 (30.5%) resided in tracts with HRL scores less than 2.5; and 1226 (69.5%) resided in tracts with HRL scores 2.5 or greater. Living in HRL areas with HRL scores 2.5 or greater was associated with a 62% increased odds of ER-negative BC among non-Hispanic Black women (odds ratio [OR], 1.62 [95% CI, 1.01-2.60]), a 97% increased odds of late-stage diagnosis among non-Hispanic White women (OR, 1.97 [95% CI, 1.15-3.36]), and a 60% increase in BC mortality overall (hazard ratio, 1.60 [95% CI, 1.17-2.18]). Similarly, PMD was associated with BC mortality among non-Hispanic White women but not among non-Hispanic Black women.

Conclusions and Relevance

The findings of this cohort study suggest that historical racist policies and persistent discrimination have modern-day implications for BC outcomes that differ by race. These findings emphasize the need for a more nuanced investigation of the social and structural drivers of disparate BC outcomes.

A Comparison of Three Area-Level Indices of Neighborhood Deprivation and Socioeconomic Status and their Applicability to Breast Cancer Mortality

Neighborhood deprivation indices are widely used in research, but the performance of these indices has rarely been directly compared in the same analysis. We examined the Area Deprivation Index, Neighborhood Deprivation Index, and Yost index, and compared their associations with breast cancer mortality. Indices were constructed for Georgia census block groups using 2011-2015 American Community Survey data. Pearson correlation coefficients and percent agreement were calculated. Associations between each index and breast cancer mortality were estimated among 36,795 women diagnosed with breast cancer using Cox proportional hazards regression. The indices were strongly correlated (absolute value of correlation coefficients > 0.77), exhibited moderate (41.4%) agreement, and were similarly associated with a 36% increase in breast cancer mortality. The similar associations with breast cancer mortality suggest the indices measure the same underlying construct, despite only moderate agreement. By understanding their correlations, agreement, and associations with health outcomes, researchers can choose the most appropriate index for analysis.

Aspirin and nonaspirin nonsteroidal antiinflammatory drug use and occurrence of colorectal adenoma in Black American women

Evidence suggests that aspirin use reduces the occurrence of colorectal neoplasia. Few studies have investigated the association among Black Americans, who are disproportionately burdened by the disease. We assessed aspirin use in relation to colorectal adenoma among Black women. The Black Women's Health Study is a prospective cohort of self-identified Black American women established in 1995. Participants reported regular aspirin use on baseline and follow-up questionnaires. Beginning in 1999, participants reported undergoing a colonoscopy or sigmoidoscopy, the only procedures through which colorectal adenomas can be diagnosed. Multivariable logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI) for associations between aspirin use and colorectal adenoma among 34 397 women who reported at least 1 colonoscopy or sigmoidoscopy. From 1997 through 2018, 1913 women were diagnosed with an adenoma. Compared to nonaspirin users, regular users had 14% (OR = 0.86, 95% CI: 0.78-0.95) lower odds of adenoma. The odds of adenoma decreased with increasing duration of aspirin use (≥10 years: OR = 0.80, 95% CI: 0.66-0.96). Initiating aspirin at a younger age was associated with a reduced adenoma occurrence (age < 40 years at initiation: OR = 0.69, 95% CI: 0.55-0.86). Regular aspirin use was associated with a decreased odds of colorectal adenoma in our study of Black women. These findings support evidence demonstrating a chemopreventive impact of aspirin on colorectal neoplasia and suggest that aspirin may be a useful prevention strategy among US Black women.

Attitudes and beliefs about sleep health among a racially and ethnically diverse sample of overweight/obese adults

OBJECTIVES

To identify and compare how sleep-related attitudes and beliefs vary among racially and ethnically diverse adults with risk factors for cardio-metabolic disease.

METHODS

This exploratory qualitative study used online focus group discussions (N = 4 groups among 17 individuals) to collect information about sleep attitudes, beliefs, and practices following participation in the Mindfulness Intervention to Improve Sleep and Reduce Diabetes Risk Among a Diverse Sample in Atlanta (MINDS) study. A rapid analyses approach was used to identify shared themes related to attitudes and beliefs about sleep health and sleep practices across participants.

RESULTS

Participants on average were 31years old, 88% female, and identified as Black/African American (52.9%), White (17.7%), Asian (11.8%), and Hispanic (17.7%). Three themes related to attitudes and beliefs about sleep health were identified: prioritization of sleep to improve one's overall health, re-evaluating sleep needs, and interpersonal barriers to sleep. For Black/African American participants prioritizing sleep was coupled with a want to minimize stress as a long-term health promotion strategy, whereas individuals of other races/ethnicities were more focused on the immediate benefits of getting sufficient sleep. Individuals had reappraised their sleep needs and worked to improve their sleep hygiene accordingly, yet still experienced barriers to sleep. The most common barrier to sleep was sharing a sleep environment with someone who had conflicting sleep routines and practices.

CONCLUSION

The results of this study suggest perceived benefits of and barriers to sleep vary by race/ethnicity, thus future interventions should be culturally tailored to enhance effectiveness.

Circadian Disruption and Colorectal Cancer Incidence in Black Women

BACKGROUND

Animal and experimental studies suggest circadian disruption increases colorectal cancer risk, but evidence in humans is limited. We examined night shift work, chronotype, and residential position within a time zone, proxies for circadian disruption, in relation to colorectal cancer risk.

METHODS

Participants in the Black Women's Health Study, a prospective cohort of 59,000 Black American women established in 1995, reported history of night shift work and chronotype on follow-up questionnaires. Residential position within a time zone was estimated using participant addresses at each questionnaire cycle. Number of colorectal cancer cases and follow-up duration varied by analysis depending on timing of exposure assessment, ranging from 204 over the 2005 to 2018 night shift work study period to 452 over the 1995 to 2018 residential position study period. Cox proportional hazards regression was used to estimate multivariable-adjusted HRs and 95% confidence intervals (CI).

RESULTS

Compared with never having worked a night shift, working a night shift for ≥10 years was associated with increased colorectal cancer risk (HR = 1.64; 95% CI, 1.01-2.66). However, shorter duration was not. The HR for evening versus morning chronotype was 0.96 (95% CI, 0.73-1.27). Westward position of residence within a time zone was not associated with colorectal cancer risk (HR per 5-degree longitude increase: 0.92; 95% CI, 0.82-1.03).

CONCLUSIONS

Our findings suggest a possible increased risk of colorectal cancer associated with long duration night shift work; however, results require confirmation in larger studies.

IMPACT

Circadian disruption from long-term night shift work may contribute to colorectal cancer development in Black women.

Abstract PD1-03: Neighborhood deprivation and breast cancer mortality among Black and White women

Background: Neighborhood deprivation is hypothesized as a potential driver of racial disparities in breast cancer mortality. However, research shows that neighborhood deprivation is associated with increased breast cancer mortality among White women, but has little to no association among Black women. No study has previously considered the intersections of race, social cohesion, or urban/rural status in the association between neighborhood deprivation and breast cancer mortality. Methods: Neighborhood deprivation was examined in relation to breast cancer mortality among 31,358 non-Hispanic Black and non-Hispanic White women diagnosed with invasive breast cancer (stage I-IIIA) between 2010-2017, followed through 2019, and identified by the Georgia Cancer Registry. Two composite scores, the Area Deprivation Index (ADI) and neighborhood deprivation index (NDI), were used to characterize neighborhood deprivation. A third composite score, the Yost index, was assessed as a measure of neighborhood socioeconomic status (SES). Each composite score was composed of factors representing six domains: poverty, income, occupation, housing, employment, and education. Data on ADI were obtained from the Neighborhood Atlas and was assessed in deciles. American Community Survey data from 2011-2015 and principal components analysis were used to derive the NDI and Yost index. Both measures were assessed in quartiles. Each composite variable was measured at the block group level and linked to patient data. Cox proportional hazards regression was used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for the association between each composite variable and breast cancer mortality, overall and by race/ethnicity. Intersectionality will be examined by considering the joint effects of race/ethnicity, social cohesion, and urban/rural status. Results: During the 9-year follow-up period, 2,353 (1,347 non-Hispanic White, 1,006 non-Hispanic Black) women died from breast cancer. Regardless of which composite score was assessed, living in the most deprived or lowest SES neighborhoods was associated with an increased risk of breast cancer mortality in models adjusted for age and race (ADI decile 10 vs. 1: HR=1.57, 95% CI 1.26-1.96; NDI quartile 4 vs. 1: HR=1.43, 95% CI 1.26-1.63; Yost index quartile 1 vs 4: HR= 1.34, 95% CI 1.18-1.51). Stratification by race/ethnicity showed associations were slightly stronger among non-Hispanic White women but null among non-Hispanic Black women. Results from analyses examining the joint effects of race/ethnicity, social cohesion, and urban/rural status are forthcoming and will be presented in December. Conclusions: Consistent with previous studies, our study found that living in a deprived neighborhood may increase breast cancer mortality among non-Hispanic White women, but not non-Hispanic Black women. Investigating the association with an intersectionality framework may help identify subgroups of women who are particularly susceptible to the adverse impact of neighborhood deprivation on breast cancer mortality.

Citation Format: Lauren E. Barber, Jasmine M. Miller-Kleinhenz, Maret L. Maliniak, Leah Moubadder, Jeffrey Switchenko, Lauren E. McCullough. Neighborhood deprivation and breast cancer mortality among Black and White women [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD1-03.

What Are the Factors Underlying Colorectal Cancer Health Disparities?

Black Americans have the highest colorectal cancer incidence and mortality rates of any U.S. racial/ethnic group. Warren Andersen and colleagues report that sociocultural, lifestyle, and healthcare factors did not explain the racial disparity in colorectal cancer incidence, but colorectal cancer screening lessened the disparity. While screening is a cornerstone of colorectal cancer prevention, an improved understanding of etiologic factors may inform additional strategies for primary prevention or risk stratification. As important "established" colorectal cancer risk factors have not been corroborated for Black Americans, this begs the question of what other etiologic factors are important for colorectal cancer development in Black American populations. See related article, p. 595.

A Prospective Analysis of Red and Processed Meat Intake in Relation to Colorectal Cancer in the Black Women's Health Study

BACKGROUND

Black Americans have the highest incidence of colorectal cancer (CRC) of any racial/ethnic group in the United States. High intake of red and processed meats has been associated with an increased CRC risk in predominately White populations. However, 3 prior studies in Black populations, who have been reported to have high intakes of red and processed meats, have reported no associations. Data on a possible association between CRC risk and SFAs and MUFAs, the primary types of fat in red and processed meats, are inconclusive.

OBJECTIVES

We prospectively assessed intakes of processed and unprocessed red meat, SFAs, and MUFAs in relation to CRC risk, utilizing data from the Black Women's Health Study (BWHS, 1995-2018).

METHODS

Dietary data were derived from validated FFQs completed in 1995 and 2001. Multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazards regression.

RESULTS

Among 52,695 BWHS participants aged 21-69 y at baseline and followed for ≤22 y, 564 women developed incident CRC. Unprocessed red meat intake was associated with a 33% increased CRC risk per 100 g/d (HR: 1.33; 95% CI: 1.03-1.71). Examination of CRC anatomic sites revealed that unprocessed red meat was associated with 2-times increased rectal cancer risk (HR: 2.22; 95% CI: 1.15-4.26). There was no evidence of an interaction with age (pinteraction = 0.4), but unprocessed red meat intake was only associated with a significant increased risk of late-onset CRC (≥50 y of age, HR: 1.41; 95% CI: 1.05-1.88). Processed red meat and total SFA and MUFA intakes were not associated with CRC risk.

CONCLUSIONS

Unprocessed red meat intake was associated with an increased CRC risk in the present study, the first positive evidence that red meat plays a role in the etiology of CRC in Black women. The findings suggest prevention opportunities.

Neighborhood disadvantage and individual-level life stressors in relation to breast cancer incidence in US Black women

BACKGROUND

Research on psychosocial stress and risk of breast cancer has produced conflicting results. Few studies have assessed this relation by breast cancer subtype or specifically among Black women, who experience unique chronic stressors.

METHODS

We used prospective data from the Black Women's Health Study, an ongoing cohort study of 59,000 US Black women, to assess neighborhood- and individual-level psychosocial factors in relation to risk of breast cancer. We used factor analysis to derive two neighborhood score variables after linking participant addresses to US Census data (2000 and 2010) on education, employment, income and poverty, female-headed households, and Black race for all households in each residential block group. We used Cox proportional hazards regression to estimate hazard ratios (HR) and 95% confidence intervals (CI) adjusted for established breast cancer risk factors.

RESULTS

During follow-up from 1995 to 2017, there were 2167 incident invasive breast cancer cases (1259 estrogen receptor positive (ER +); 687 ER negative (ER-)). For ER- breast cancer, HRs were 1.26 (95% CI 1.00-1.58) for women living in the highest quartile of neighborhood disadvantage relative to women in the lowest quartile, and 1.24 (95% CI 0.98-1.57) for lowest versus highest quartile of neighborhood socioeconomic status (SES). For ER+ breast cancer, living in the lowest quartile of neighborhood SES was associated with a reduced risk of ER+ breast cancer (HR = 0.83, 95% CI 0.70-0.98). With respect to individual-level factors, childhood sexual abuse (sexual assault ≥ 4 times vs. no abuse: HR = 1.35, 95% CI 1.01-1.79) and marital status (married/living together vs. single: HR = 1.29, 95% CI 1.08-1.53) were associated with higher risk of ER+, but not ER- breast cancer.

CONCLUSION

Neighborhood disadvantage and lower neighborhood SES were associated with an approximately 25% increased risk of ER- breast cancer in this large cohort of Black women, even after control for multiple behaviors and lifestyle factors. Further research is need to understand the underlying reasons for these associations. Possible contributing factors are biologic responses to the chronic stress/distress experienced by individuals who reside in neighborhoods characterized by high levels of noise, crime and unemployment or the direct effects of environmental toxins.

Predicted Vitamin D Status and Colorectal Cancer Incidence in the Black Women's Health Study

BACKGROUND

Observational studies, mostly among White populations, suggest that low vitamin D levels increase colorectal cancer risk. African Americans, who are disproportionately burdened by colorectal cancer, often have lower vitamin D levels compared with other populations.

METHODS

We assessed predicted vitamin D score in relation to colorectal cancer among 49,534 participants in the Black Women's Health Study, a cohort of African American women followed from 1995 to 2017 through biennial questionnaires. We derived predicted vitamin D scores at each questionnaire cycle for all participants using a previously validated prediction model based on actual 25-hydroxyvitamin D values from a subset of participants. We calculated cumulative average predicted vitamin D score at every cycle by averaging scores from cycles up to and including that cycle. Using Cox proportional hazards regression, we estimated hazard ratios (HR) and 95% confidence intervals (CI) for colorectal cancer incidence according to predicted score quartiles.

RESULTS

Over follow-up, 488 incident colorectal cancers occurred. Compared with women in the highest quartile of predicted vitamin D score, those in the lowest had an estimated 41% (HR = 1.41; 95% CI, 1.05-1.90) higher colorectal cancer risk. Comparable HRs were 1.44 (95% CI, 1.02-2.01) for colon and 1.34 (95% CI, 0.70-2.56) for rectal cancer.

CONCLUSIONS

Low vitamin D status may lead to elevated colorectal cancer risk in African American women.

IMPACT

Our findings, taken together with established evidence that vitamin D levels are generally lower in African Americans than other U.S. groups, suggest that low vitamin D status may contribute to the disproportionately high colorectal cancer incidence among African Americans.

Racial Disparities and Sex Differences in Early- and Late-Onset Colorectal Cancer Incidence, 2001-2018

Background

Colorectal cancer (CRC) incidence rates have increased in younger individuals worldwide. We examined the most recent early- and late-onset CRC rates for the US.

Methods

Age-standardized incidence rates (ASIR, per 100,000) of CRC were calculated using the US Cancer Statistics Database’s high-quality population-based cancer registry data from the entire US population. Results were cross-classified by age (20-49 [early-onset] and 50-74 years [late-onset]), race/ethnicity (non-Hispanic White, non-Hispanic Black, Hispanic, American Indian/Alaskan Native, Asian/Pacific Islander), sex, anatomic location (proximal, distal, rectal), and histology (adenocarcinoma, neuroendocrine).

Results

During 2001 through 2018, early-onset CRC rates significantly increased among American Indians/Alaskan Natives, Hispanics, and Whites. Compared to Whites, early-onset CRC rates are now 21% higher in American Indians/Alaskan Natives and 6% higher in Blacks. Rates of early-onset colorectal neuroendocrine tumors have increased in Whites, Blacks, and Hispanics; early-onset colorectal neuroendocrine tumor rates are 2-times higher in Blacks compared to Whites. Late-onset colorectal adenocarcinoma rates are decreasing, while late-onset colorectal neuroendocrine tumor rates are increasing, in all racial/ethnic groups. Late-onset CRC rates remain 29% higher in Blacks and 15% higher in American Indians/Alaskan Natives compared to Whites. Overall, CRC incidence was higher in men than women, but incidence of early-onset distal colon cancer was higher in women.

Conclusions

The early-onset CRC disparity between Blacks and Whites has decreased, due to increasing rates in Whites—rates in Blacks have remained stable. However, rates of colorectal neuroendocrine tumors are increasing in Blacks. Blacks and American Indians/Alaskan Natives have the highest rates of both early- and late-onset CRC.

Impact

Ongoing prevention efforts must ensure access to and uptake of CRC screening for Blacks and American Indians/Alaskan Natives.

A Prospective Analysis of Red and Processed Meat Intake in Relation to Colorectal Cancer Incidence in the Black Women's Health Study

Objectives

African Americans have the highest incidence of colorectal cancer (CRC) of any racial/ethnic group in the US. High intake of red and processed meats has been shown to increase CRC risk in populations of European ancestry, but evidence in African American populations is limited. The association between saturated and monounsaturated fatty acid intakes, the primary types of fat in red and processed meat, and CRC is inconclusive. Thus, we prospectively assessed the intake of red and processed meats and dietary saturated and monounsaturated fatty acids in relation to CRC risk, utilizing the Black Women's Health Study (BWHS, 1995–2018).

Methods

Dietary data were derived from validated food frequency questionnaires completed in 1995 and 2001 by 52,695 BWHS participants. Multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazards regression adjusted for energy, fiber, and discretionary fat.

Results

Over a median follow-up of 22 years, 564 women developed incident CRC. Total red meat intake was associated with a 25% increased risk of CRC per 100 g/day (HR = 1.25; 95% CI: 0.94–1.66), which was primarily due to intake of unprocessed red meat (HR = 1.33, 95% CI: 1.05–1.70). Processed meat and total saturated and monounsaturated fatty acid intakes were not associated with an increased risk of CRC.

Conclusions

Unprocessed red meat intake was associated with an increased risk of CRC in this cohort of African American women. The strong evidence, now including African American women, that red meat plays a role in the etiology of CRC suggests opportunities for prevention.

Funding Sources

This research was funded by National Institutes of Health grants U01 CA164974 and R01 CA058420, the Karin Grunebaum Cancer Research Foundation, and the Boston University Peter Paul Career Development Professorship.

Abstract PO-223: Racial disparities in early- and late-onset colorectal cancer incidence, 2001- 2016

Background. Colorectal cancer (CRC) incidence rates have increased in younger individuals worldwide. A recent US study reported increases among both non- Hispanic whites (NHW) and non-Hispanic blacks (NHB), but did not consider other racial/ethnic groups. Thus, we examined the most recent CRC rates for the US by age, race/ethnicity, and anatomic location. Methods. Age-standardized incidence rates (ASR, per 100,000) of CRC were calculated for 2001-2002 through 2015-2016 using the US Cancer Statistics Database, which includes data from the National Program of Cancer Registries and the Surveillance, Epidemiology, and End Results Program. US Cancer Statistics covers the entire US population. Results were cross- classified by age (20-49 [early-onset] and 50-74 years [late-onset]), race/ethnicity (NHW, NHB, Hispanic, American Indian/Alaskan Native [AIAN], Asian/Pacific Islander [API]), and location (proximal, distal, rectal). To examine the change in ASR over time, annual percent change (APC) was calculated using joinpoint regression models. Results. Historically, NHB have had the highest rates of early-onset CRC. However, in 2015-2016, early-onset CRC rates were highest in AIAN (ASR=14.72), followed by NHB (ASR=13.20) and NHW (ASR=12.31). The rate of early-onset proximal colon cancer was highest in NHB (ASR=4.83), which was 62% higher than the rate in NHW (ASR=2.98). Early-onset distal colon and rectal cancer rates were highest in AIAN (ASR=3.98 and 6.43, respectively). Between 2001-2002 and 2015-2016, early-onset CRC rates significantly increased among NHWs (APC=1.62%) and AIAN (APC=3.33%). Racial disparities in incidence of early-onset CRC have decreased between NHB and NHW, due to increasing rates in NHW. Among NHW, early-onset CRC has significantly increased for all CRC locations, with the largest increase for rectal cancer (APC=2.22%). Early-onset rates of rectal cancer also significantly increased for AIAN (APC=4.38%) and Hispanics (APC=0.76%), while rates of proximal colon cancer significantly increased for AIAN (APC=2.21%). Rates of late-onset CRC have significantly decreased in all racial/ethnic groups. However, compared to NHW (ASR=82.48), late-onset CRC rates remain 32% higher in NHB (ASR=108.91) and 18% higher in AIAN (ASR=97.06). Conclusion. Early-onset CRC rates have been increasing, while late-onset CRC rates have decreased. The racial disparity between NHB and NHW in incidence of early-onset CRC has decreased, but this is due to increases in NHW—not decreases in NHB. NHB and AIAN have the highest rates of both early-and late-onset CRC. To counter these trends, research should focus on identifying predictors of early-onset CRC to determine who should be screened prior to age 50 and identify underlying causes of early-onset CRC. Further, ongoing prevention efforts must ensure access to screening colonoscopies for AIAN and NHB.

Citation Format: Jessica L. Petrick, Lauren E. Barber, Shaneda Warren Andersen, Andrea A. Florio, Julie R. Palmer, Lynn Rosenberg. Racial disparities in early- and late-onset colorectal cancer incidence, 2001- 2016 [abstract]. In: Proceedings of the AACR Virtual Conference: Thirteenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2020 Oct 2-4. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(12 Suppl):Abstract nr PO-223.

Abstract C040: Predictors of blood biospecimen provision among African American women

Background: Under-representation of minority populations in research utilizing biospecimens can prohibit advancements in cancer research, treatment and survivorship from reaching those who are most vulnerable, potentially increasing cancer health disparities. Barriers and facilitators to biospecimen provision among under-represented populations are not well understood. This study examined predictors of biospecimen provision in a large cohort of black women.

Methods: The Black Women's Health Study (BWHS), an ongoing prospective cohort study of African American women from across the U.S. followed since 1995, initiated a four-year effort in 2013 to collect blood biospecimens. Of 48,956 BWHS participants invited to provide a blood sample, 27% (n=13,037) did so. We used logistic regression analyses to estimate multivariable odds ratios (OR) and 95% confidence intervals (CI) for associations of participant characteristics with sample provision, adjusted for age and education.

Results: The strongest predictors of providing a blood sample were having had a physical exam in the past two years (OR 3.90 [95% CI 3.70-4.11]), and, independently, mammographic screening in the past two years (OR 1.88 [1.76-2.01]). Other predictors included educational status (OR 1.30 [1.21-1.39] for &gt;16 vs. ≤12 years of education) and having a family history of cancer (OR 1.16 [1.11-1.21]). Women had lower odds of giving a blood sample if they reported more frequent experiences of racism in their daily lives (OR 0.83 [0.77-0.89] for highest vs. lowest level of racism score) or lived in a rural vs. urban area (OR 0.75 [0.69-0.80]). History of cancer was not associated with sample provision. Because interaction with the health care system was such a strong predictor, we repeated analyses restricted to those who had not reported a recent physical exam. No new associations emerged, but both mammographic screening (OR 4.23 [3.81-4.70]) and daily racism (OR 0.64 [0.55-0.75]) became stronger predictors in this group.

Conclusions: Recent utilization of the health care system and higher levels of education were the strongest predictors of agreement to provide a blood sample for research in this cohort of black women, while living in a rural area and having more frequent experiences of racism, a unique characteristic of this population, were barriers. Innovative recruitment efforts may be necessary for greater inclusion of individuals who are less educated and infrequent users of the health care system. In addition, the persistent reality of racism in the U.S. may continue to play a role in the under-representation of black Americans in cancer research utilizing biospecimens.

Citation Format: Lauren E. Barber, Julie R. Palmer, Kimberly A. Bertrand, Catharine Wang. Predictors of blood biospecimen provision among African American women [abstract]. In: Proceedings of the Eleventh AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2018 Nov 2-5; New Orleans, LA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl):Abstract nr C040.

Pre- and perinatal factors and incidence of breast cancer in the Black Women's Health Study

PURPOSE

The purpose of the study was to investigate the association between pre- or perinatal factors and breast cancer risk among African American women.

METHODS

Participants in the Black Women's Health Study, a prospective cohort of 59,000 African American women, reported birth weight, preterm birth, twin or triplet status, maternal age at birth, birth order, and having been breastfed during infancy at various times during follow-up from 1997 to 2015. Numbers of incident cases ranged from 312 for breastfed analyses to 1,583 for twin or triplet analyses. Using multivariable Cox proportional hazards regression, we estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for associations between each factor and breast cancer risk overall and by estrogen receptor (ER) status.

RESULTS

Compared to birth weights of 5 lbs. 8 oz.-8 lbs. 13 oz., low (< 5 lbs. 8 oz.) and high (> 8 lbs. 13 oz.) birth weights were associated with increased breast cancer risk; HRs (95% CI) were 1.19 (0.98-1.44) and 1.26 (0.97-1.63), respectively. Associations were similar by ER status. Having been born to a mother aged ≥ 35 years versus < 20 years was associated with risk of ER+ (HR 1.59, 95% CI 1.10-2.29), but not ER- breast cancer. Other perinatal factors were not associated with breast cancer.

CONCLUSION

African American women with a low or high birth weight or born to older mothers may have increased breast cancer risk. Trends towards delayed child birth and higher birth weights, coupled with disproportionately high rates of low birth weight among African Americans, may contribute to increases in breast cancer incidence.

Abstract 2543: A family affair: Prostate cancer risk and family history of breast or prostate cancer

Background - There is suggestive evidence of familial clustering of breast and prostate cancer in first-degree relatives; women with a family history of prostate cancer are at increased risk of breast cancer. Few studies have investigated joint family history of breast and prostate cancer and prostate cancer risk, and no study to date has examined lethal prostate cancer.

Methods - We studied 42,672 from the Health Professionals Follow-up Study between 1996 to 2012. During follow-up, 4,258 prostate cancer cases were diagnosed, of whom 380 were lethal disease. Men self-reported family history of breast and prostate cancer, including in siblings or parents. Using cause-specific hazards regression, we estimated hazard ratios (HR) and 95% confidence intervals (CI) of the association between family history and prostate cancer risk and progression.

Results - About 8% of men had a family history of prostate cancer, 8.7% had a family history of breast cancer, and 1.4% of men had a family history of both breast and prostate cancer. A family history of prostate cancer was significantly associated with an increased risk of prostate cancer (HR: 1.69; 95% CI: 1.54-1.85). Increased risk was higher for men with a father diagnosed with prostate cancer (HR: 1.64 95% CI: 1.49-1.80) than for men with a diagnosis in a brother(s) (HR: 1.51 95% CI: 1.27-1.80). A positive family history of breast cancer was associated with a small, but significant 22% increased risk (HR: 1.22; 95% CI: 1.11-1.35). Familial breast cancer in a sister (HR: 1.22 95% CI: 1.06-1.41) increased risk more than familial breast cancer in a mother (HR: 1.12; 95% CI: 0.99-1.25). Men with a family history of both prostate and breast cancer had a 52% (HR: 1.52; 95%CI: 1.23-1.88) increased risk of prostate cancer compared to men with no family history of either cancer. Risk of lethal prostate cancer was also significantly increased for men with a positive family history of prostate cancer (HR: 1.64; 95% CI: 1.20-2.24), as well as for men with a family history of breast cancer (HR: 1.47; 95% CI: 1.07-2.01).

Conclusions - These results support the findings of familial aggregation of breast and prostate cancer, and for the first time suggest an association between familial breast cancer and lethal prostate cancer. Data from this prospective study have translational relevance for family counseling of cancer patients.

Citation Format: Lauren E. Barber, Travis A. Gerke, Sarah C. Markt, Giovanni Parmigiani, Lorelei A. Mucci. A family affair: Prostate cancer risk and family history of breast or prostate cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2543.

High-throughput screening and rapid inhibitor triage using an infectious chimeric Hepatitis C virus

The recent development of a Hepatitis C virus (HCV) infectious virus cell culture model system has facilitated the development of whole-virus screening assays which can be used to interrogate the entire virus life cycle. Here, we describe the development of an HCV growth assay capable of identifying inhibitors against all stages of the virus life cycle with assay throughput suitable for rapid screening of large-scale chemical libraries. Novel features include, 1) the use of an efficiently-spreading, full-length, intergenotypic chimeric reporter virus with genotype 1 structural proteins, 2) a homogenous assay format compatible with miniaturization and automated liquid-handling, and 3) flexible assay end-points using either chemiluminescence (high-throughput screening) or Cellomics ArrayScan™ technology (high-content screening). The assay was validated using known HCV antivirals and through a large-scale, high-throughput screening campaign that identified novel and selective entry, replication and late-stage inhibitors. Selection and characterization of resistant viruses provided information regarding inhibitor target and mechanism. Leveraging results from this robust whole-virus assay represents a critical first step towards identifying inhibitors of novel targets to broaden the spectrum of antivirals for the treatment of HCV.

Nitrogen-appended N-alkylsulfonamides as inhibitors of gamma-secretase

The synthesis and gamma-secretase inhibition data for a series of nitrogen-appended N-alkylsulfonamides (11-47) are described. Inhibition of brain Abeta in transgenic mice was demonstrated by two of these compounds (23 and 44).

The influence of stimulus envelope and fine structure on the binaural masking level difference

A masking level difference (MLD) paradigm was used to investigate the influence of stimulus envelope and stimulus fine-structure characteristics on monaural and binaural hearing. The degree of masker envelope fluctuation was manipulated by selecting narrow-band noises (50 Hz) on a continuum of values of the normalized fourth moment of the envelope. The noises were specified as low-noise noise (LNN), medium-noise noise (MNN), and high-noise noise (HNN). Fine-structure cues were studied by measuring thresholds at 500 and 4000 Hz, regions in which the availability of such cues to the auditory system differ substantially. In addition, thresholds were measured for Gaussian noise maskers (GN) and for maskers having a flat magnitude spectrum, termed equal-magnitude noise (EMN) maskers. The results indicated lower NoSo thresholds for LNN than for the other four masker types. Furthermore, there were no differences in threshold for maskers having moderate and high degrees of envelope fluctuation (MNN and HNN). The NoS pi thresholds were not significantly different across masker type and were characterized by large individual differences among the seven listeners. The results are considered in relation to models of monaural and binaural processing. Consistent with previous reports, the results indicate that binaural detection depends on interaural differences in the stimulus envelope and fine structure at low frequencies and changes in the envelope at high frequencies.

Renal transepithelial phosphate secretion: luminal membrane voltage and Ca2+ dependence

The role of apical membrane electrical potential, the possibility of K+ channel involvement, and the role of extracellular Ca2+ in transepithelial P(i) secretion were examined in primary monolayer cultures of flounder renal proximal tubule cells in Ussing chambers. Exposure to 200 nM thapsigargin (TG) significantly increased net P(i) secretion. In TG-stimulated tissues, substitution of 100 mM KCl for 100 mM NaCl in the luminal medium depolarized the apical membrane potential from -64 +/- 2.8 to -26 +/- 3.9 mV and strongly inhibited net P(i) secretion. In 32P(i)-preloaded tissues, cell-to-lumen exit of 32P(i) was significantly decreased to approximately 50% of control by high luminal K+ while cell-to-peritubular bath movement was unchanged. Addition of BaCl2 (2 mM) or charybdotoxin (20 nM) to the luminal surface significantly reduced TG-stimulated net P(i) secretion. The elevation of bath Ca2+ from 2 to 5 mM significantly increased secretory flux and decreased reabsorptive flux. The effect of TG on net P(i) secretion was reduced by the Ca2+ channel blocker verapamil (VE, 100 microM) to 65% of control and by calmodulin antagonist W-7 (20 microM) to 35% of control but it was not blocked by the protein kinase inhibitor H-7 (100 microM). VE also significantly inhibited the P(i) secretion induced by acidification of the peritubular bathing medium. The data indicate that transepithelial P(i) secretion induced by TG is significantly influenced by apical membrane electrical polarity, which may be regulated in part by Ca(2+)-activated K+ channels.

PTH-sensitive K(+)- and voltage-dependent Pi transport by chick renal brush-border membranes

Brush-border membrane vesicles (BBMV) from chick (Gallus gallus) kidneys were used to examine possible pathways of Pi transport associated with Pi secretion. Preloading with 6 mM Pi trans-stimulated 32Pi uptake in the absence of Na+, indicating facilitation. Inside-positive voltage (100 mM K+, out > in, +valinomycin) increased Pi uptake from 161 +/- 4.4 to 241 +/- 16.1 pmol.mg protein-1.5s-1 at pH 7.5 (in = out). Gradients characterized by extravesicular pH (pHo) of 5.5 vs. intravesicular pH (pHi) of 7.5, 100 mM K+ (out > in), without and with valinomycin, further increased uptake to 664 +/- 148.5 and 946 +/- 90.8 pmol.mg protein-1.5s-1, respectively. Carbonyl cyanide m-chlorophenylhydrazone (CCCP) had no effect on the latter response, but with 100 mM K+ (in = out), valinomycin decreased the response more than one-half, implicating a H+ diffusion potential. Generation of this potential with pHo 5.5 vs. pHi 7.5 and CCCP did not drive concentrative Pi uptake in absence of K+. Parathyroid hormone (PTH) treatment significantly increased this BBMV K(+)- and voltage-dependent Pi up-take compared with the parathyroidectomized (PTX) condition. The values of maximal uptake rate (Vmax) in PTH vs. PTX BBMV were 5,330 and 1,976 pmol.mg protein-1.5s-1, respectively. K(+)-dependent transport was inhibited by arsenate, phosphonoacetic acid, and vanadate. Together, the data indicate that this PTH-sensitive, voltage- and K(+)-dependent monovalent Pi transporter could be the mechanism by which Pi exits, cell-to-lumen, during renal tubular Pi secretion.

Biosynthesis of oxygen-detoxifying enzymes in Bdellovibrio stolpii

Axenically grown Bdellovibrio stolpii (i.e., grown independently of the host) was examined for superoxide dismutase, catalase, and peroxidase activities. Kinetics of enzyme synthesis were determined for aerobically grown cultures and for cultures exposed to 100% oxygen. Enzymatic activities varied with the age of the culture. Normally grown cultures exhibited maximum activity during the first 10 h of growth and again as the stationary phase was approached, beginning at about 48 h. Polyacrylamide gel electropherograms of cell-free extracts revealed that B. stolpii contained one major band (1) and two minor bands (II, III) of superoxide dismutase activity. Each of these enzymes was inactivated by H2O2, indicating that they were iron-containing enzymes. Manganese-containing superoxide dismutase was not detected in B. stolpii. Increased oxygenation did not appreciably stimulate enzyme synthesis, for only superoxide dismutase was induced, reaching maximum activity at 10 h and then rapidly falling to normal levels. Superoxide dismutase appears to be the main enzymatic defense against oxygen toxicity in B. stolpii. Induction of superoxide dismutase with 100% oxygen was manifested as an increase in the intensities of the two minor bands of activity, suggesting that isozyme I is constitutive, whereas isozymes II and III are inducible. The induction of isozymes II and III by 100% oxygen was prevented by an inhibitor of protein biosynthesis, chloramphenicol.

Acetylene reduction (nitrogen fixation) associated with corn inoculated with Spirillum

Sorghum and corn breeding lines were grown in soil in field and greenhouse experiments with and without an inoculum of N2-fixing in Spirillum strains from Brazil. Estimated rates of N2 fixation associated with field-grown corn and sorghum plants were less than 4 g of N2/ha per day. The mean estimated N2-fixation rates determined on segments of roots from corn inoculated with Spirillum and grown in the greenhouse at 24 to 27 degrees C were 15 g of N2/ha per day (16 inbreds), 25 g of N2/ha per day (six hybrids), and 165 g of N2/ha per day for one hybird which was heavily inoculated. The corresponding mean rates determined from measurements of in situ cultures of the same series of corn plants (i.e., 16 inbreds, six hybrids, and one heavily inoculated hybrid) were 0.4, 2.3, and 1.1 g of N2/ha per day, respectively. Lower rates of C2H2 reduction were associated with control corn cultures which had been treated with autoclaved Spirillum than with cultures inoculated with live Spirillum. No C2H2 reduction was detected in plant cultures treated with ammonium nitrate. Numbers of nitrogen-fixing bacteria on excised roots of corn plants increased an average of about 30-fold during an overnight preincubation period, and as a result acetylene reduction assays of root samples after preincubation failed to serve as a valid basis for estimating N2 fixation by corn in pot cultures. Plants grown without added nitrogen either with or without inoculum exhibited severe symptoms of nitrogen deficiency and in most cases produced significantly less dry weight than those supplied with fixed nitrogen. Although substantial rates of C2H2 reduction by excised corn roots were observed after preincubation under limited oxygen, the yield and nitrogen content of inoculated plants and the C2H2-reduction rates by inoculated pot cultures of corn, in situ, provided no evidence of appreciable N2 fixation.

Nitrogen fixation associated with grasses in Oregon

Nitrogen fixation associated with both natural grasslands and grain crops of Oregon was studied using the acetylene-reduction assay. A number of the grasses collected has some acetylene-reducing activity. Agrostis tenuis Sibth. had substantially greater activity than any of the other species, with a mean rate estimated at 37 g N2 fixed per hectare per day. Assuming 100 days of activity, about 3 kg of N2 would be fixed per hectare per year. This quantity of nitrogen may be important in the maintenance of this species under natural conditions. Nitrogen-fixing microorganisms were isolated from the root surfaces of some of the grasses. Cultures of Bacillus macerans, Bacillus polymyxa, and Enterobacter cloacoa were isolated from wheat roots as were two cultures which have not been assigned a specific taxonomic classification. Strains of N2-fixing Bacillus species and Gram-negative aerobic bacteria were isolated from Festuca and Agrostis.

Characterization of a nitrogen-fixing bacterial strain from the roots of Digitaria sanguinalis

Rates of nitrogen fixation of 3 to 10 g of N2 fixed per hectare per day were associated with root systems of Digitaria sanguinalis. A Gram-negative motile aerobic bacterial strain that was capable of N2 fixation was isolated from a washed root sample of one of these plants. Optimal growth and N2 fixation occurred at a pH of about 6.5, a temperature of 30-37 degrees C, and at a pO2 of about 0.01 atm. Increased rates of N2 fixation resulted when this strain was grown in mixed cultures with aerobic or facultative bacteria. Observations of cellular and cultural morphology and results of biochemical and physiological studies indicate that the isolate may be related to the Azotobacteraceae but that it is not identical with any of the members of this family. The importance of N2 fixation by this isolate in nature is unknown.

Effect of pH and oxygen tension on staphylococcal growth and enterotoxin formation in fermented sausage

Commercial fermented 0sausages that contained significant numbers of viable coagulase-positive staphylococci were found to have the growth localized in the outermost areas of the sausage where oxygen tension was highest. Staphylococci were found to be more acid-tolerant aerobically than anaerobically. With chemical acidulation of sausage, growth could be controlled both aerobically and anaerobically with approximately 1.5% glucono delta lactone. Biological acidulation with a high inoculum of Pediococcus cerevisiae inhibited anaerobic staphylococcal growth but failed to suppress aerobic growth completely. A staphylococcal count of approximately 4 x 10(7) cells/g of sausage appeared to be necessary to produce detectable enterotoxin A within 24 hr in sausage. A minor difference existed in the relative rates of production of the different types of enterotoxin. Detectable enterotoxin A was produced in 24 hr in sausage held in atmospheres containing 10, 15, and 20% oxygen. In an atmosphere containing 5% oxygen, toxin was detected after 48 hr of incubation. No toxin was detected after 120 hr under anaerobic conditions. Most staphylococcal strains tested initiated growth and produced detectable enterotoxin aerobically at a pH of 5.1 in broth media. Anaerobically, however, most strains failed to produce detectable enterotoxin below pH 5.7.