Outcomes and toxicity in african-american and caucasian patients in a randomized adjuvant chemotherapy trial for colon cancer.
BACKGROUND
Previous studies have demonstrated that African-Americans with colon cancer have worse overall and stage-specific survival rates than Caucasians. Such differences could reflect variation in access to health care, in tumor biology, or in treatment efficacy. Little is known about potential differences in chemotherapy-related toxicities between African-Americans and Caucasians. In this study, we examined survival and toxic effects among African-American and Caucasian patients enrolled in a large, randomized phase III trial of adjuvant chemotherapy for resected colon cancer.


METHODS
We analyzed data on 3380 patients (344 African-Americans and 3036 Caucasians) enrolled in a randomized trial of adjuvant 5-fluorouracil-based chemotherapy in patients with stage II (high risk) and stage III colon cancer to evaluate differences in outcomes and toxicity. We compared disease-free survival (DFS) and overall survival (OS) between African-Americans and Caucasians by the Kaplan-Meier method, computed Cox proportional hazards by multivariable analysis, and compared treatment-related toxicity rates by Fisher's exact test. All statistical tests were two-sided.


RESULTS
We found no differences in DFS or OS between African-American and Caucasian patients. Five-year DFS was 57% (95% confidence interval [CI] = 52% to 62%) for African-Americans and 58% (95% CI = 56% to 60%) for Caucasians (P =.15), and 5-year OS was 65% (95% CI = 60% to 70%) for African-Americans and 66% (95% CI = 64% to 68%) for Caucasians (P =.38). On multivariable analysis, no statistically significant difference in disease recurrence or death was detected between the racial/ethnic groups (hazard ratios for African-Americans versus Caucasians: disease recurrence = 1.1, 95% CI = 0.9 to 1.3; death = 1.1, 95% CI = 0.9 to 1.3). Treatment-related toxicity differed between the African-American and Caucasian patients, with African-Americans experiencing statistically significantly lower rates of diarrhea (P<.001), nausea (P<.001), vomiting (P =.01), stomatitis (P<.001), and overall toxicity (P =.005).


CONCLUSIONS
In this study of patients with similar access to health care resources and treatment with adjuvant chemotherapy, we found similar 5-year DFS and OS in African-Americans and Caucasians with stage II and III colon cancer. The two groups derived similar benefits from adjuvant chemotherapy. Moreover, African-Americans appeared to experience less treatment-related toxicity.
McCollum
A David
AD
A. D. McCollum, R. J. Mayer, C. S. Fuchs, Dana-Farber Cancer Institute, Boston, MA, USA. amccollum@partners.org
Catalano
Paul J
PJ
Haller
Daniel G
DG
Mayer
Robert J
RJ
Macdonald
John S
JS
Benson
Al B
AB
Fuchs
Charles S
CS
D000964:Antimetabolites, Antineoplastic / Q000627:therapeutic use*; D044383:Black People; D017024:Chemotherapy, Adjuvant; D003110:Colonic Neoplasms / Q000188:drug therapy* / Q000208:ethnology* / Q000401:mortality; D005472:Fluorouracil / Q000009:adverse effects / Q000627:therapeutic use*; D006801:Humans; D016896:Treatment Outcome; D044465:White People; D001741:Black or African American
D000964:Antimetabolites, Antineoplastic; D005472:Fluorouracil