One of the U.S. National Cancer Institute's (NCI) largest cancer registry databases may be underreporting outpatient radiation therapy (RT) treatment of breast cancer patients, according to an article published online June 29 in Cancer.
Since 1973, the Surveillance, Epidemiology, and End Results (SEER) program has been collecting data from regional cancer registries that represent 26% of the U.S. population. Over the past decade, researchers have been questioning whether SEER data are complete. This is of particular concern because researchers use SEER data -- and in some studies, only SEER data -- to determine the appropriateness of patient care.
A multi-institutional research team conducted a study to determine whether the SEER registry accurately captured outpatient RT treatment of breast cancer patients, and if regional registries submitting data to SEER differed in reporting accuracy with respect to underreporting. If underreporting was identified, the researchers also wanted to determine if it varied systematically by clinical or sociodemographic factors.
The study targeted breast cancer patients ages 21 to 79 in metropolitan Detroit or Los Angeles, who were diagnosed with ductal carcinoma in situ (DCIS) or invasive breast cancer between June 2005 and February 2007. The patient sample included all African-American women at both sites and all Hispanic women treated in the Los Angeles area, along with a random sample of non-African-American and non-Hispanic women at both sites.
More than 3,200 patients were invited to participate approximately 10 months after diagnosis by completing a survey regarding their treatment. Seventy-three percent of the patients completed surveys, and 95% of this group (2,179 patients) stated that they had received or would receive radiation therapy. Ultimately, a total of 1,927 patients qualified for analysis.
Disparities
The research teams from the University of Michigan and the University of Southern California compared self-reported data on radiation therapy with RT treatments reported in the SEER registry records. Approximately 20% of patients who reported receiving radiation therapy were not recorded in the SEER registries as having undergone treatment, according to the researchers.
Significant regional disparities were identified. Underreporting in Los Angeles was almost three times greater than in Detroit, at 32.0% and 11.25%, respectively. In both registries, underreporting was significantly associated with disease stage, patient income, mastectomy, and whether diagnosis occurred at a hospital not accredited by the American College of Surgeons, among other factors.
The researchers suggested that increased time between diagnosis and radiation therapy treatments due to chemotherapy, combined with RT being performed in outpatient cancer centers, made it difficult for cancer registrars to capture the data.
"The findings of the current study are sobering," wrote lead author Dr. Reshma Jagsi, PhD, associate professor of radiation oncology at the University of Michigan, and colleagues.
Future studies should not use the SEER dataset alone to determine rates of RT receipt until the quality of data in the other SEER registries is investigated more closely, the authors recommended.
"With increased interest in comparative effectiveness research, more and more researchers are using registry databases like SEER," Jagsi said in a statement about the study. "If the quality of the data in some of these databases has limitations, these must be understood to avoid potentially misleading conclusions that affect both clinical decision-making and policy."
