Researchers led by Dr. Nancy Schoenborn from John Hopkins University found that existing mortality prediction algorithms may be missing important variables that are associated with receipt of cancer screening and long-term mortality.
"These findings suggest that screening decisions need to be individualized and not solely dependent on mortality prediction," the authors wrote.
Current guidelines recommend against routine breast, prostate, and colorectal cancer screenings in older adults with less than 10 years of life expectancy. However, questions remain on how to apply these guidelines in actual practice.
The research team sought to examine whether cancer screening remains significantly associated with all-cause mortality in older adults who undergo routine breast and prostate screening after accounting for both comorbidities and functional status. To do so, they constructed two separate cohorts for breast and prostate cancer screenings, with data drawn from the Health and Retirement Study linked to Medicare claims.
The breast cancer screening cohort included 3,257 women with an average age of 77.8 years, while the prostate cancer screening cohort included 2,085 men with an average age of 76.1 years.
Receiving a screening mammogram was associated with a lower hazard of all-cause mortality after accounting for all index variables. Meanwhile, none of the potential confounders lessened the association between screening and mortality except for cognition, which attenuated the adjusted hazard ratio for mammograms from 0.67 to 0.73.
"This suggests that in addition to all the demographic, health, social, and personal characteristics that we examined, there is still residual selection bias between those who do and do not receive cancer screening in terms of mortality risk," study authors wrote.
Screening PSA was used for the prostate cancer screening cohort. While a weaker, but still statistically significant association with a lower hazard of all-cause mortality was found for this group, the adjusted hazard ratio went from 0.88 to 0.92. This made PSA screening no longer statistically significant.
Researchers said continued cancer screening for older patients may still be appropriate.
"They are at risk of being categorized incorrectly as overscreening in the current paradigm," the authors wrote.
They also wrote that they were surprised that most variables, with the exception of cognition, did not lessen the association between receiving either cancer screening and all-cause mortality when added to base models.
"The reasons behind this finding are not clear," they said.
The breast cancer screening results are interesting, but not surprising, said Dr. Stamatia Destounis, chief of the American College of Radiology's Breast Imaging Commission.
"Individuals who continue to screen regardless of predicted life expectancy can benefit from early detection and improved outcomes, ultimately improving their life expectancy," Destounis told AuntMinnie.com. "It is important to note that, out of all the potential confounders, there was a significant association between screening mammograms and cognition. Although, screening mammography still was associated with reduced hazard for death."
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