Even though black patients and white patients with rectal cancer are seeing oncologists at equal rates, black patients are less likely to receive adjuvant care, researchers report. Black patients who had an initial consultation with an oncologist were 22.9% less likely than white patients to undergo chemotherapy and 11.6% less likely to have radiation treatment, according to a study published online May 13 in the Journal of the National Cancer Institute.
“The findings were not what we expected,” lead author Arden Morris, MD, MPH, assistant professor of surgery at the University of Michigan Medical School and chief of general surgery at the VA Ann Arbor Healthcare System, said in an interview. “We assumed that black patients had less access to a medical oncologist.”
Previous studies have identified factors associated with the nonuse of chemotherapy among rectal patients; these include older age at diagnosis, excessive comorbidity, and lack of referral to an oncologist. However, no studies have examined reasons for racial disparities in treatment rates.
Rectal cancer survival rates have improved in recent years, but black patients continue to have a substantially worse prognosis than white patients. The long-term survival rates after rectal cancer surgery are 14% to 20% lower among black patients, and the authors note that these disparities in survival are at least partly attributable to the lower use of adjuvant radiation and chemotherapy in black patients.
In this study, Dr. Morris and colleagues used data from the Surveillance, Epidemiology, and End Results (SEER)–Medicare database between 1992 and 1999 to identify patients who had been hospitalized for resection of stage 2 or 3 rectal cancer. Of the 134 black patients and 2582 white patients who were included in the analysis, there were no statistically significant differences in the frequency of consultation with a medical oncologist (73.1% for blacks vs 74.9% for whites) or a radiation oncologist (56.7% vs 64.8%). However, black patients were less likely than white patients to consult with both a medical oncologist and a radiation oncologist (49.2% vs 58.8%).
“There were no issues of insurance,” said Dr. Morris. “All of these patients were covered by Medicare.”
Even though black and white patients were equally likely to consult with an oncologist, the researchers found that the use of adjuvant therapy was significantly different between the 2 groups. Only 54.1% of black patients received chemotherapy, compared with 70.2% of white patients. Radiation therapy was administered to 73.7% of black patients and 83.4% of white patients. Among the patients who consulted with both a medical and radiation oncologist, there was a 16.3% difference; 60.6% of black patients and 76.9% of white patients underwent both chemotherapy and radiation.
The researchers examined baseline patient characteristics that might account for racial disparities in treatment and found that individual demographic and clinical variables played a minimal role. The nonuse of chemotherapy among white patients was associated with older age at diagnosis and more comorbidities. However, that was not the case with black patients.
“Among white patients, those who were the most frail were most likely not to receive chemotherapy,” said Dr. Morris. “But in black patients, those who were relatively the healthiest were the least likely to get chemotherapy. This opens the door to more questions rather than giving us answers.”
The reasons for the differences in care remain unclear. The authors note that racial disparities in the use of recommended adjuvant treatment are not the result of easily identifiable attributes of the patient or the provider.
“What we do know is that black patients are not less likely to see a medical oncologist,” Dr. Morris told Medscape Oncology. “Our plan is now to find out what is happening between seeing the oncologist and receiving the chemotherapy. We need to talk to the patients and find out exactly what the barriers are to care.”
In a follow-up study, the researchers plan to interview patients who have received treatment for rectal cancer to find out about their decisions related to adjuvant therapy.
“Hopefully, we will have more answers,” she said, “although we may end up with yet more questions.”
The study was funded by the American Cancer Society and the National Cancer Institute.
J Natl Cancer Inst. 2008;100:738-744.
Reviewed by Dr. Ramaz Mitaishvili
