CHICAGO – Access to equal care decreases but does not eliminate the survival disparities between black and white patients with rectal cancer, according to investigators from the University of Cincinnati, Ohio.
After rigorous propensity score matching of thousands of black and white patients for patient, disease, and treatment characteristics, median survival was 109.6 months among white patients and 85.8 months among black patients (J Am Coll Surg. 2015 Nov [doi: 10.1016/j.jamcollsurg.2015.07.056]).
“Blacks have worse outcomes, but we don’t have a clear explanation,” explained investigator and surgery resident Dr. Meghan Nolan. For now, the findings suggest that it might be a good idea to start screening black patients before age 50 years, perhaps even as early as age 40 years.
“We are urging people to screen at a lower age in black patients,” Dr. Nolan said at the annual clinical congress of the American College of Surgeons.
Racial disparities in rectal cancer are well known. The investigators wanted to see if they simply are because of unequal access to care, so they analyzed 178,414 white and 18,385 black patients in the National Cancer Data Base from 1998 to 2006.
Mean 5-year survival for blacks was 50.7%, compared with 56.2% for whites, and black patients were more likely to present with stage IV disease. Such findings aren’t new, the investigators noted.
To account for the difference in late-stage presentation, the investigators limited their analysis to patients with stage I-III rectal cancer. But even then, 5-year survival was 66.7% among whites and 58.7% among blacks.
That might have had something to do with the fact 85% of white patients, but only 78% of black patients, had surgery for those potentially curable lower-stage tumors. Among those who didn’t undergo surgery, patient refusal was slightly more common among black patients than white patients, which suggests that “cultural factors may be playing a role” in the surgery disparity, Dr. Nolan said.
The investigators controlled for the different surgery rates by limiting their analysis to stage I-III patients who had appropriate operations. The survival gap narrowed but did not disappear: 65.8% of white patients were alive at 5 years, compared with 61% of black patients. Blacks were also more likely to have positive margins on pathology. “I’m not sure why. That was a surprise,” Dr. Nolan said.
The propensity score matching led the team to conclude that there’s more at work than differences in access to care. A total of 7,569 pairs of black and white patients were matched for age at diagnosis, gender, insurance coverage, income, education, facility type, tumor stage, Charlson-Deyo score, surgical management, margin status, and other potential confounders.
Every matched patient completed their recommended therapy, and there was no statistical difference between matched black and white patients who received appropriate, stage-specific chemoradiation. Still, the survival differences persisted.
Dr. Nolan had no relevant disclosures.