Understanding Gender, Race and Ethnicity in Colorectal Cancer Screening

Colorectal cancer (CRC) is the third most common cancer and the third leading cause of cancer death in both men and women in the United States. Since CRC impacts both genders, it is actually the second most common cause of cancer death overall [1]. CRC screening has been proven to result in a reduction in CRC mortality [2]. CRC screening reduces mortality both through the earlier detection of cancers and offers the opportunity for primary prevention i.e. removal of pre-cancerous polyps [3]. The American Cancer Society (ACS) and the United States Preventive Services Task Force (USPSTF) recommend screening for individuals over the age of 50, regardless of race, gender or ethnicity. Due in large part to the increasing awareness and availability of colonoscopy, the rates of CRC screening have risen significantly in the last 10 years. However, the overall rate of CRC screening remains unacceptably low, around 60% [4].


Introduction
Colorectal cancer (CRC) is the third most common cancer and the third leading cause of cancer death in both men and women in the United States. Since CRC impacts both genders, it is actually the second most common cause of cancer death overall [1]. CRC screening has been proven to result in a reduction in CRC mortality [2]. CRC screening reduces mortality both through the earlier detection of cancers and offers the opportunity for primary prevention i.e. removal of pre-cancerous polyps [3]. The American Cancer Society (ACS) and the United States Preventive Services Task Force (USPSTF) recommend screening for individuals over the age of 50, regardless of race, gender or ethnicity. Due in large part to the increasing awareness and availability of colonoscopy, the rates of CRC screening have risen significantly in the last 10 years. However, the overall rate of CRC screening remains unacceptably low, around 60% [4].
To increase CRC screening rates, populations who are refractory to screening must be identified and assisted. Numerous factors influence whether or not a patient participates in screening. This review focuses on three key determinants of screening: gender, race, and ethnicity. change in the pattern when eliminating studies which do not include colonoscopy, the most common choice of CRC testing. Nine studies showed no association with female gender, seven studies showed a negative association and one, show a positive association.
Race in CRC Screening: Disparities in CRC mortality persist in racial subgroups and only around 49% of eligible African-Americans undergo CRC screening [4]. We identified 38 analyses which examined race and CRC screening. Table 2 presents CRC screening outcomes for individuals of non-white race. Non-white (African American/Black) race was associated with lower rates of screening in 18 studies. There was no association between race and screening in 15 studies. In 5 studies, a positive association was noted. Most analyses used colonoscopy or overall CRC as their outcome of interest. The majority of these analyses were adjusted for some measure of socio economic status (SES) or access to care. When considering only studies which utilized national data sets and included colonoscopy a clearer pattern emerges, 12 studies revealed a negative association between African American/Black race and CRC screening while five showed no association, and one showed a positive association.
Ethnicity in CRC Screening: Only around 37% of eligible Hispanics undergo CRC screening [4]. Table 3

Discussion
Improvements in CRC screening have not equally permeated our society and mortality disparities persist. Socioeconomic status, culture and lack of adequate health insurance have been critical barriers [13]. Variation in disparity by three factors, race, gender and ethnicity presents a complex picture. SES and access to care are variables that likely cluster differently depending on race, gender, and ethnic subgroup. SES and access are meaningful determinants of screening and these modifiable factors represent an opportunity for improvement. The "gender gap" is closing. This reduction in the gender gap is credited in part to rapid uptake of colonoscopy by women and public health efforts to dispel the myth that CRC is a "man's disease". Improved CRC screening in women will be a success story to guide improved screening in other groups. Interestingly, African American males are less likely to screen when compared with their female counterparts [17]. Given that women access the health care system more frequently than men [14], women may more ready and able to respond to screening messages and recommendations. Of the four studies which specifically examined insurance as a predictor of CRC screening [8,[15][16][17], one stratified according to gender. The effect of not having insurance was strongly predictive of CRC screening in men but not in women [14]. For men, lack of insurance may equate to full disengagement from the care system while African American women may be more able to work around this barrier and remain connected to the health care system.
The national racial gap in CRC screening rates is not yet closed [18]. A small majority of the studies included here, examining race and CRC screening, indicated that Black or African-American race was associated with lower rates of screening. When considering only those studies in the last 10 years with a national cohort; a more distinct pattern of negative association emerges; there are 11 studies showing a negative association between race and CRC screening and six showing no association. Some of the differences may be regional and may include state-based variations in funding or outreach programs. In Delaware, which has one of the highest statewide CRC screening rate,

Studies w/Negative Association Sample Outcome
Liss et al. [ community-based outreach targeted specifically to African Americans is credited with eliminating race-based discrepancies in CRC screening [19]. Likewise, one of the studies which showed no negative association with race was done in Massachusetts which has universal access and very high rates of screening compared with other states. Other factors which may explain this variability include difference between black men and black women, differences in urban vs. rural and again, SES and access [10,20,21].
The variations in this literature demonstrate that gender and race are not consistently barriers to screening. However, Hispanic ethnicity does seem to consistently confer a barrier to screening. While individual preferences and cultural/social biases undoubtedly contribute to racial, gender and ethnic disparities, cancer burden in underserved groups also relates to socioeconomic status [1,12]. In fact, lower socioeconomic status confers increased cancer risk regardless of race. However, the impact of SES on screening is variable within race/gender subgroups.
This literature on Hispanic ethnicity and CRC screening was the most straightforward. A clear majority of studies demonstrate that Hispanic ethnicity is associated with a lower likelihood of having been screened. This is not surprising given that this group has consistently been found to have the lowest cancer screening rate nationally. Literature in this area suggests that certain subgroups, e.g. Mexican women and newer immigrants and non-English speakers, may be especially at risk [22]. Social integration or connectedness may also be very important in cancer screening in Hispanics [23]. The path to help Hispanics to complete CRC screening is not well elucidated but finding this path will become increasingly crucial as this minority grows to represent an increasing proportion of the U.S. population.

Conclusion
Although CRC screening rates are improving, disparities in screening and mortality persist. How barriers and facilitators interact to promote or reduce screening disparities is complex and not yet fully elucidated. Future research should seek to characterize barriers and facilitators, particularly in Hispanics, under/uninsured and individuals of low SES. In populations experiencing low rates of screening, more interventional studies are needed.