SAN FRANCISCO-A continuing increase in endoscopic examinations to diagnose colorectal cancer appears to coincide with a reduction in deaths caused by the cancer-with most of the impact due to decreases in mortality among patients diagnosed with early stage disease (Abstract 508).
Over the 14-year study period, Catalina Mosquera, MD, a resident in surgery at East Carolina University Brody School of Medicine, Greenville, N.C., reported an increase in screening endoscopy from 41 percent in 1998 to 64 percent in 2012 (P<0.0001). She also observed an inverse relationship between increased screening endoscopy and incidence of colorectal cancer-60.03 cases per 100,000 persons in 1998 to 34.82 cases per 100,000 in 2012 (P< 0.0001).
In her poster presentation, Mosquera also noted there was a comparable trend in mortality. In 1998, the colorectal cancer mortality was 23.27 per 100,000 persons and then decreased to 13.47 per 100.000 persons by 2012. The calculations were based on the Surveillance, Epidemiology, and End Results (SEER) from seven states.
"When evaluating states individually, the association between increasing endoscopic screening and the trends in incidence and mortality were robust (P<0.0001). However, when states were analyzed collectively, the association of screening with decreases in incidence (P=0.005) and mortality (P=0.06) was weaker," she explained. The states included in this study are California, Connecticut, Georgia, Hawaii, Iowa, New Mexico, and Utah.
"We should be screening with colonoscopy," Mosquera told Oncology Times. "We found that screening reduces mortality in early stage colon cancer, but it does not decrease mortality in late stage disease. If you present with late stage disease, it is sort of 'game over.'"
She said the mortality in early colorectal cancer decreased from 45.4 cases per 100,000 people in 1998 to 25.7 cases per 100,000 cases in 2012 (p<0.0001), but the reduction in mortality among patients diagnosed with late stage disease was "minimal"-10.5 cases per 100,000 people in 1998 to 7.2 cases per 100,000 persons in 2012 (P=0.014).
During the same time frame, Mosquera noted there was a slight decrease in fecal occult blood testing for colorectal cancer-dropping from 25 percent of the population at risk for disease in 1998 to 23 percent in 2012 (P<0.0001).
"We are saving the people who would have died by finding the disease in its early stage with colonoscopy. The early stage cancer reduction in mortality is driving these results," she said.
Targeting Colon Cancer
In commenting on the study, David H. Robbins, MD, Associate Chief of the Center for Advanced Therapeutic Endoscopy at Lenox Hill Hospital, New York, noted, "Colon cancer is almost entirely preventable, but compliance with universal, age-appropriate screening still hovers around 50 percent nationwide
"Concerns about sedation, adherence to a modified diet and bowel cathartic prior to the exam, fear of finding a colon cancer, and increasing costs to our patients are some of the most persistent and challenging barriers doctors face in the war on colon cancer," he said.
"Myths and misconceptions about the pain and recovery period after a colonoscopy, as well as misguided reports in the media that colonoscopy may not be as effective as initially thought, have hindered awareness and outreach efforts by various healthcare advocacy groups," Robbins added.
"The real tragedy is the preventable nature of this common affliction-the No. 2 cancer in America-and the many hurdles practitioners face in eradicating this lethal cancer."
Cancer Screening
In performing the study, Mosquera and colleagues selected states that had both colorectal cancer screening prevalence estimates from the Behavioral Risk Factor Surveillance System and cancer registry data from SEER. The researchers focused on individuals who were 50 years of age or older. They used SEER*Stat to compute age-adjusted incidence and mortality rates; coefficients were computed to evaluate the association between screening and outcomes.
"Increased screening for colorectal cancer coincides with a decrease in incidence and mortality, disproportionality decreasing early stage cancer," Mosquera said "This correlation is very strong within states but diminished between states, suggesting factors in addition to screening are influencing the epidemiology of colorectal cancer."
She said the research team embarked on the study after noting that "screening for neoplasia of the breast and prostate has come under increasing scrutiny. However, little is understood regarding the temporal impact of screening on incidence and mortality for colorectal cancer."
The researchers said fecal blood screening tests and flexible sigmoidoscopy had been evaluated in colorectal cancer, but the results from these studies for reduction in mortality have been mixed.
"Colonoscopy has been evaluated in observational studies and these data suggest superiority to other screening approaches," Mosquera said. Hence, they accessed the population databases to determine if those observations held up. And they did, she reported.
Ed Susman is a contributing writer.