Patient age and sex are useful for predicting risk of advanced neoplasia at screening CT colonography (CTC), but body mass index (BMI) and positive family history seem to have little impact, according to a study published online June 10 in Cancer.
The results could have implications for patient selection and stratification, according to Cesare Hassan, MD, of Nuovo Regina Margherita Hospital, Rome, and colleagues.
“In cases of limited resources, which are likely to occur when [colorectal cancer] screening is recommended for all adults aged >50 years, it makes sense for health systems to target patients with a greater expected benefit to best use the available economic and medical resources,” they wrote.
Hassan and colleagues analyzed data from 7,620 consecutive patients referred for first-time screening CTC from 2004 to 2011. Pathology results were recorded and odds ratios were determined to express association of advanced neoplasia with age, sex, BMI and family history.
Results showed 276 patients (3.6 percent) were diagnosed with advanced neoplasia. Age and male sex were independent predictors of advanced neoplasia, with mean odds ratios per 10-year increase of 1.8 and 1.7, respectively. BMI and a positive family history of colorectal cancer were not predictors, according to the authors.
The number needed to screen (NNS) to detect one case of advanced neoplasia varied by sex and age. Women aged 55 and younger had a NNS as high as 51, while men older than 65 had a NNS of 10. When stratified by age and sex, there was a two-fold variation in the efficiency of post-CTC colonoscopy to confirm advanced neoplasia, suggesting more conservative surveillance could be adopted for CTC-positive patients who are at a lower risk.
Despite the association between sex and advanced neoplasia at screening, Hassan and colleagues noted that sex is not explicitly included in any guidelines. The NNS for women appears to be on a decade-long delay compared with men, with women younger than age 65 years and men younger than age 55 years having NNS below the study-wide mean NNS of 28.
“Thus, it would seem reasonable to propose different age recommendations for CTC screening according to sex, whereas perhaps a less costly strategy, such as fecal occult blood testing, could be used earlier.”