LOS ANGELES – Overall 5-year survival rates for anal cancer in the United States have steadily improved since the 1970s, but the incidence of disease continues to rise. In addition, African Americans with anal cancer have significantly and disproportionally lower 5-year survival rates, compared with whites.
Those are key findings from an analysis of Surveillance, Epidemiology and End Results (SEER) data that primary study author Dr. Marco Ferrara presented at the annual meeting of the American Society of Colon and Rectal Surgeons.
“Disparities in health-related outcomes for diseases such as cancer are unfortunately commonly observed,” Dr. Ferrara’s mentor and the senior study author Dr. Daniel I. Chu said in an interview in advance of the meeting. “African Americans in particular have higher cancer-specific death rates, higher rates of advanced cancer on initial diagnosis, and less frequent use of cancer screening tests. While our understanding of disparities continues to progress for the more common cancers (lung, breast, prostate, colorectal), comparatively fewer data are available for anal cancer. This gap in knowledge is important because anal cancer incidence has actually been increasing in the U.S. population over the past decades. While effective treatment is available, we asked if disparities exist in anal cancer.”
To find out, the researchers used the national SEER database to identify all patients with cancer of the anus, anal canal, and anorectum from 1973 to 1999 (Period 1; a total of 6,755 cases) and 2000 to 2012 (Period 2; a total of 18,027 cases) and stratified them by race. They determined the incidence, staging, and treatment provided for each group and used 2000 Census data to calculate the age-adjusted annual incidence of anal cancer. The primary outcome was 5-year survival.
More than half of patients (61%) were female, 86% were white, 10% were African American, and the remaining 4% were from other ethnic groups. Dr. Ferrara, who is a fourth-year surgery resident at Baptist Health System in Birmingham, Ala., reported that between Periods 1 and 2, the overall incidence of anal cancer increased from 1.1 to 1.8 cases per 100,000 individuals. The overall incidence was higher among African Americans, compared with whites (1.6 vs. 1.3 cases per 100,000 individuals, respectively). The incidence among African-American males was slightly higher, at 1.9 cases per 100,000 individuals.
The researchers found that nearly half of patients (48%) presented with localized disease, while 31% had regional disease. Between Periods 1 and 2 the proportion of patients who received any treatment for anal cancer increased from 63% to 74%. The use of radiation therapy increased from 61% to 72%, while the use of local excisions and abdominoperineal resections decreased from 60% to 45%. Overall, African Americans were more likely than whites to not undergo recommended surgery (9.8% vs. 8.7%, respectively) or to refuse recommended surgery (1.8% vs. 1.1%; P less than .05 for both associations).
Overall 5-year survival for anal cancer improved from 63% in Period 1 to 70% in Period 2 (P less than .05). However, African Americans had significantly lower 5-year survival rates, compared with whites in both time periods (53% vs. 64% in Period 1, and 62% vs. 71% in Period 2; P less than .05 for both associations).
“Health disparities exist in anal cancer with African Americans faring worse than Caucasian patients,” said Dr. Chu, who is a gastrointestinal surgeon at the University of Alabama at Birmingham. “While the etiologies for these disparities are unclear, anal cancer is a very treatable disease when caught early, regardless of race. Screening should be done for those at higher risk, such as patients with a family history of anal cancer, HIV, or HPV [human papillomavirus]. Ultimately, more research is needed to understand the factors driving these disparities at the patient, provider, and health care system level.”
He acknowledged certain limitations of the study, including its retrospective nature, the inability to assess the potential impact of education status and other social factors, and the generalizability of its findings, since SEER is limited to major cancer hospitals.
The researchers reported having no financial disclosures.