Background: Colorectal cancer (CRC) is the second leading cause of cancer deaths in the United States. Poor survival for CRC is associated with delayed diagnosis. To remedy this problem, race and ethnicity are routinely used to target intensified CRC screening when information about health insurance is not available. We sought to distinguish roles of demographic variables and bowel segments as predictors of delayed (AJCC stage II-IV) vs. early (in situ and stage I) diagnosis of colorectal adenocarcinoma in the diverse California population.
Methods: Demographic variables and right (C18.0-C18.4) vs. left (C18.5-C18.7, C19.9 & C20.9) bowel origin for 66,806 CRC cases diagnosed in 2004-2008 were extracted from the California Cancer Registry and analyzed by logistic regression as delayed vs. early stage.
Results: Of the CRC cases, 65% were non-Hispanic (NH) white, 15% Hispanic, 13% Asian/Other and 7% NH black. Logistic regression showed increased odds of delayed vs. early diagnosis (OR, 95% confidence limits) for age <40 (2.58,2.26-2.94), 40-49 (1.71,1.60-1.83) and 75+ (1.05,1.02-1.09) relative to 50-74 years. Contrast with NH whites, odds ratios for delayed vs. early stage were: 1.05,0.99-1.13 (NH blacks); 1.08,1.02-1.13 (Hispanics) and 1.05,1.00-1.11 (Asian/Others). Females had higher odds of delayed CRC diagnosis (1.09,1.06-1.13) than males. Lower odds ratios for delayed stage diagnosis were seen for successively lower to highest SES quintiles (OR4:5=1.08,1.03-1.14; OR3:5=1.13,1.08-1.19; OR2:5=1.18,1.12-1.24; and OR15=1.21,1.14-1.28; Trend p <0.0001). Origin in the right bowel vs. left showed higher odds of delayed vs. early diagnosis (1.68,1.63-1.74). No significant product interactions between race/ethnicity and SES were detected (p=0.47).
Discussion: Our findings identify younger and older than age 50-74 at diagnosis, female gender, Hispanic ethnicity, right or proximal bowel, and lower SES as independent predictors of delayed CRC diagnosis. Low SES persists as the most robust predictor of delayed diagnosis, independent of race/ethnicity and other covariates. Consistent with other studies, females showed higher odds of delayed stage CRC than males. More than 70% of CRC (76% of delayed stage) cases were in race/ethnic groups not routinely classified as underserved that are neglected in many intensified screening recommendations. Findings for higher odds of delayed CRC diagnosis in the right bowel challenge current screening practices that favor FOBT over colonoscopy in underserved populations. Delayed stage diagnosis among persons younger than 50 can be partly remedied by screening that targets familial adenomatous polyposis (FAP) and hereditary nonpolyposis colorectal cancer (HNPCC) syndromes. Our findings show the value of including SES, together with Hispanic ethnicity, FAP and HNPCC syndromes, and female gender when targeting intensified and egalitarian CRC screening in the diverse California population where health insurance information is not available.
Citation Information: Cancer Epidemiol Biomarkers Prev 2010;19(10 Suppl):A47.