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Opting out of cancer screenings linked to increased overall mortality

Patients who did not adhere to recommended cancer screening tests were significantly more likely to die from other causes, according to research published in JAMA Internal Medicine.

“Patient nonadherence to chronic disease prevention guidelines is associated with increased mortality,” Dudith Pierre-Victor, PhD, and Paul F. Pinsky, PhD, both from the division of cancer prevention at the National Cancer Institute, wrote. “The most cogent explanation for these findings is that nonadherence to protocol screenings was a marker for a general behavioral profile of nonadherence to medical tests and treatments and that this behavioral profile was associated with increased mortality.”

Pierre-Victor and Pinsky conducted a secondary analysis of the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening trial to determine whether nonadherence to cancer screening tests is associated with mortality from unrelated causes.

The researchers randomly assigned patients aged 55 to 74 at 10 screening centers in the United States to either an intervention or control arm from Nov. 8, 1993, to Jul. 2, 2001. The first follow-up phase was through 13 years or Dec. 31, 2009. The second follow-up phase occurred from May 18, 2011, to Dec. 31, 2012.

Participants in the intervention arm (n = 64,567; 29,537 women; mean age, 62.3 years) received protocol screening tests, including chest radiographs and flexible sigmoidoscopy for both men and women, prostate-specific antigen tests and digital rectal examinations for men and cancer antigen 125 tests and transvaginal ultrasonography for women. Participants were categorized as either fully adherent (received all sex-specified screening tests at baseline), partially adherent (received some but not all baseline tests) or nonadherent (received no baseline tests).

Data indicated that 85.3% of participants were adherent (n = 55,065), 3.9% were partially adherent (n = 2,548) and 10.8% were nonadherent (n = 6,954) with the baseline screening protocol.

After excluding deaths from cancers studied in the PLCO Cancer Screening trial and controlling for age, sex and race/ethnicity, the researchers found that during the 10 years of follow-up, the HRs of mortality were 1.73 (95% CI, 1.6-1.89) for nonadherent participants and 1.36 (95% CI, 1.19-1.54) for partially adherent participants compared with those who were fully adherent. Adjusting for medical risk factors for mortality and behavioral-related factors reduced the HR to 1.46 (95% CI, 1.34-1.59) for nonadherent participants compared with those who were fully adherent.

“We found statistically significant and clinically important differences in all-cause mortality ... by cancer screening adherence status; those differences remained significant after adjusting for demographic, medical, and behavioral characteristics,” Pierre-Victor and Pinsky concluded. “Future studies should investigate this association in clinical care settings outside of a research trial context.”

In an accompanying editorial, Deborah Grady, MD, MPH, and Monica Parks, MD, both from the University of California, San Francisco, wrote that the study by Pierre-Victor and Pinsky was “interesting,” but questioned whether the findings will have any real clinical effect, arguing that encouraging patients to be adherent to cancer screening guidelines will not decrease mortality from unrelated causes.

However, they noted that compliance bias is important.

“We should view the findings of observational studies where the risk factor requires adherence to a drug or behavior with some skepticism,” they wrote. “This effect is particularly notable in observational studies of preventive interventions in the primary care setting.” – by Alaina Tedesco

Disclosures: The authors report no relevant financial disclosures.