Receipt of Cancer Screening Is a Predictor of Life Expectancy

Effect of screening mammography on the risk of breast cancer deaths and of all-cause deaths: a systematic review with meta-analysis of cohort studies

OBJECTIVES

Observational cohort studies are used to evaluate the effectiveness of screening mammography in women offered screening. Because screening mammography has no effect on causes of death other than breast cancer (BC), cohort studies should show reductions in the risk of BC death substantially greater than possible reductions in the risk of all-cause death. We assessed the risk of BC deaths and of all-cause (or of nonBC) deaths associated with screening mammography attendance reported in cohort studies.

STUDY DESIGN AND SETTING

Cohort studies published from 2002 to 2022 on women invited to screening mammography were searched in PubMed, Web of Sciences, Scopus, and in review articles. Random effect meta-analyses were performed using relative risks (RRs) of death between women who attended screening compared to women who did not attend screening.

RESULTS

Eighteen cohort studies were identified, nine that reported RRs of BC deaths only, five that reported RRs of all-cause deaths only, and four that reported RRs for both BC deaths and all-cause deaths. The latter four cohort studies reported 12-76 times more all-cause deaths than BC deaths. The random-effect summary of RR for BC mortality in screening attendees vs nonattendees was 0.55 (95% CI: 0.50-0.60) in 13 cohort studies. The summary of RR for all-cause mortality was 0.54 (0.50-0.58) in 10 cohort studies. In the four cohort studies that evaluated both outcomes, the summary of RRs were 0.63 (0.43-0.83) for BC mortality and of 0.54 (0.44-0.64) for all-cause mortality.

CONCLUSION

The similar relative reductions in breast- and all-cause (or nonBC) mortality indicates that screening mammography attendance is an indicator of characteristics associated with a lower risk of dying from any cause, including from BC, which observational studies have falsely interpreted as a screening effect.

Extending Age Ranges in Breast Cancer Screening in Four European Countries: Model Estimations of Harm-to-Benefit Ratios

Simple Summary

Breast cancer screening causes harms and benefits. The balance between the two varies by age. By applying microsimulation modelling, we compared several age ranges of screening in four European countries (the Netherlands, Finland, Italy and Slovenia) and evaluated the respective harm-to-benefit ratios. In all countries, adding screening between the ages 45 and 49 or 70 and 74 resulted in more life-years gained and more breast cancer deaths averted, but at the expense of increases in harms. Adapting the age range of breast cancer screening is an option to improve harm-to-benefit ratios in all four countries. The prioritization of considered harms and benefits affects the interpretation of results.

Abstract

The main benefit of breast cancer (BC) screening is a reduction in mortality from BC. However, screening also causes harms such as overdiagnosis and false-positive results. The balance between benefits and harms varies by age. This study aims to assess how harm-to-benefit ratios of BC screening vary by age in the Netherlands, Finland, Italy and Slovenia. Using microsimulation models, we simulated biennial screening with 100% attendance at varying ages for cohorts of women followed over a lifetime. The number of overdiagnoses, false-positive diagnoses, BC deaths averted and life-years gained (LYG) were calculated per 1000 women. We compared four strategies (50–69, 45–69, 45–74 and 50–74) by calculating four harm-to-benefit ratios, respectively. Compared to the reference strategy 50–69, screening women at 45–74 or 50–74 years would be less beneficial in any of the four countries than screening women at 45–69, which would result in relatively fewer overdiagnoses per death averted or LYG. At the same time, false-positive results per death averted would increase substantially. Adapting the age range of BC screening is an option to improve harm-to-benefit ratios in all four countries. Prioritization of considered harms and benefits affects the interpretation of results.

Association Between Receipt of Cancer Screening and All-Cause Mortality in Older Adults

IMPORTANCE

Guidelines recommend against routine breast and prostate cancer screenings in older adults with less than 10 years' life expectancy. One study using a claims-based prognostic index showed that receipt of cancer screening itself was associated with lower mortality, suggesting that the index may misclassify individuals when used to inform cancer screening, but this finding was attributed to residual confounding because the index did not account for functional status.

OBJECTIVE

To examine whether cancer screening remains significantly associated with all-cause mortality in older adults after accounting for both comorbidities and functional status.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study included individuals older than 65 years who were eligible for breast or prostate cancer screening and who participated in the 2004 Health and Retirement Study. Data were linked to Medicare claims from 2001 to 2015. Data analysis was conducted from January to November 2020.

MAIN OUTCOMES AND MEASURES

A Cox model was used to estimate the association between all-cause mortality over 10 years and receipt of screening mammogram or prostate-specific antigen (PSA) test, adjusting for variables in a prognostic index that included age, sex, comorbidities, and functional status. Potential confounders (ie, education, income, marital status, geographic region, cognition, self-reported health, self-care, and self-perceived mortality risk) of the association between cancer screening and mortality were also tested.

RESULTS

The breast cancer screening cohort included 3257 women (mean [SD] age, 77.8 [7.5] years); the prostate cancer screening cohort included 2085 men (mean [SD] age, 76.1 [6.8] years). Receipt of screening mammogram was associated with lower hazard of all-cause mortality after accounting for all index variables (adjusted hazard ratio [aHR], 0.67; 95% CI, 0.60-0.74). A weaker, but still statistically significant, association was found for screening PSA (aHR 0.88; 95% CI, 0.78-0.99). None of the potential confounders attenuated the association between screening and mortality except for cognition, which attenuated the aHR for mammogram from 0.67 (95% CI, 0.60-0.74) to 0.73 (95% CI, 0.64-0.82) and the aHR for PSA from 0.88 (95% CI, 0.78-0.99) to 0.92 (95% CI, 0.80-1.05), making PSA screening no longer statistically significant.

CONCLUSIONS AND RELEVANCE

In this study, cognition attenuated the observed association between cancer screening and mortality among older adults. These findings suggest that existing mortality prediction algorithms may be missing important variables that are associated with receipt of cancer screening and long-term mortality. Relying solely on algorithms to determine cancer screening may misclassify individuals as having limited life expectancy and stop screening prematurely. Screening decisions need to be individualized and not solely dependent on life expectancy prediction.

Use of Lung Cancer Screening With Low-Dose Computed Tomography in the Medicare Population

Objective

To describe rates of low-dose computed tomography (LDCT) and all chest computerized tomography (CT) before and after Centers for Medicare and Medicaid Services (CMS) initiated reimbursement and requirements for screening and to describe factors associated with receipt of LDCT.

Patients and Methods

Retrospective cross-sectional study of Medicare enrollees aged 55 to 77 in Parts A and B Medicare without HMO enrollment in a 20% national sample (n=3,887,430 in 2010, 4,200,875 in 2015, and 4,145,542 in 2016). The outcomes were receipt of LDCT and any chest CT from January 1, 2010, to December 31, 2016. Other measures included enrollee demographic characteristics and diagnoses, including diagnoses of tobacco use.

Results

The number of enrollees aged 55 to 77 with LDCT rose throughout 2015 and early 2016, and then plateaued. In 2016, 0.44% of enrollees, and 2.21% of those with a tobacco-use diagnosis, underwent LDCT screening. There were increases in the rate of any chest CT (LDCT or diagnostic) between January 1, 2010 and December 31, 2016, and most of this was accounted for by LDCTs.

Conclusions

Two years after CMS approval for lung cancer screening reimbursement, less than 5% of the Medicare population eligible for screening received LDCT. More work is required to identify and modify the barriers for LDCT screening.

Association of Nonadherence to Cancer Screening Examinations With Mortality From Unrelated Causes: A Secondary Analysis of the PLCO Cancer Screening Trial

IMPORTANCE

Patient nonadherence to chronic disease prevention guidelines is associated with increased mortality. Nonadherence to offered cancer screening tests may be associated with mortality among middle-aged and older adults.

OBJECTIVE

To evaluate the association between nonadherence to cancer screening tests and mortality in the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening trial, excluding mortality from cancers studied in the trial.

DESIGN, SETTING, AND PARTICIPANTS

Randomization at 10 US screening centers occurred from November 8, 1993, to July 2, 2001. Original follow-up was through 13 years or December 31, 2009. Participants were re-consented to further follow-up starting May 18, 2011, and were observed until December 31, 2012. Protocol screening tests for the PLCO Cancer Screening trial intervention arm participants (N = 77 443) included chest radiographs and flexible sigmoidoscopy for both sexes, prostate-specific antigen tests and digital rectal examinations for men, and cancer antigen 125 tests and transvaginal ultrasonography for women. At baseline, participants completed a self-administered questionnaire. The cohort was classified into those receiving all sex-specified PLCO Cancer Screening trial screening tests at baseline (fully adherent), those receiving some but not all baseline tests (partially adherent), and those receiving no baseline tests (nonadherents). Secondary analysis was ad hoc in the original trial protocol. Statistical analysis was conducted from November 24, 2017, to August 29, 2018.

MAIN OUTCOMES AND MEASURES

Mortality was ascertained via mailed annual study update questionnaires and searches of the National Death Index. Cox proportional hazards regression was used to analyze the association between mortality and adherence, controlling for various covariates.

RESULTS

Of 77 443 participants in the intervention arm, 64 567 (29 537 women and 35 030 men; mean [SD] age, 62.3 [5.3] years) were included in the analysis based on consenting to trial participation before randomization and being eligible for all screening tests. Overall, 55 065 participants (85.3%) were adherent, 2548 (3.9%) were partially adherent, and 6954 (10.8%) were nonadherent with the baseline screening protocol. Within 10 years of follow-up, the hazard ratio of mortality, excluding deaths from cancers studied in the PLCO Cancer Screening trial and controlling only for age, sex, and race/ethnicity (model 1), was 1.73 (95% CI, 1.60-1.89) for nonadherent compared with fully adherent participants and 1.36 (95% CI, 1.19-1.54) for partially compared with fully adherent participants. After adjustment for medical risk factors for mortality and behavioral-related factors (model 2), the hazard ratio decreased to 1.46 (95% CI, 1.34-1.59) for nonadherent compared with fully adherent participants.

CONCLUSIONS AND RELEVANCE

Among participants in a screening trial for multiple cancers, a nonadherence behavior profile marked by nonadherence to protocol screenings was associated with higher overall mortality (excluding deaths from cancers studied in the trial). The generalizability of this finding to routine clinical practice should be assessed.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT00002540.

A cohort study of mammography screening finds that comorbidity measures are insufficient for controlling selection bias

OBJECTIVE

To examine the potential of claims-based comorbidity measures for controlling selection bias in observational studies of mammography screening.

STUDY DESIGN AND SETTING

Based on claims data of a large German Statutory Health Insurance fund, the single comorbidities considered by the Charlson, Elixhauser, Multipurpose Australian Comorbidity Scoring System, and M3 comorbidity measures were identified for mammography screening participants and nonparticipants. Total death rates within 4 years after screening invitation were compared. Cox proportional hazards regressions were performed unadjusted and adjusted for age, federal state of residence, and comorbidity.

RESULTS

Among 1,247,919 insured women aged 50-68 years (56.2% participants), 10,311 participants (death rate 375.8/100,000 person-years) and 18,113 nonparticipants (death rate 854.8/100,000 person-years) died from any cause during the follow-up. The unadjusted hazard ratio (HR) for death from any cause for participants vs. nonparticipants was 0.44 (99.9% confidence interval 0.42-0.46). Adjustments attenuated the HR to a maximum of 0.52 (0.50-0.54).

CONCLUSION

The lower short-term all-cause mortality among participants cannot be explained by mammography screening effects and should be interpreted as selection bias. Adjusting for comorbidities only slightly attenuated this bias. Future studies should examine whether claims data include further information that is beneficial to adequately control selection bias in observational studies of mammography screening.

Use of Breast Cancer Screening and Its Association with Later Use of Preventive Services among Medicare Beneficiaries

Purpose To retrospectively assess whether there is an association between screening mammography and the use of a variety of preventive services in women who are enrolled in Medicare. Materials and Methods U.S. Medicare claims from 2010 to 2014 Research Identifiable Files were reviewed to retrospectively identify a group of women who underwent screening mammography and a control group without screening mammography in 2012. The screened group was divided into positive versus negative results at screening, and the positive subgroup was divided into false-positive and true-positive findings. Multivariate logistic regression models and inverse probability of treatment weighting were used to examine the relationship between screening status and the probabilities of undergoing Papanicolaou test, bone mass measurement, or influenza vaccination in the following 2 years. Results The cohort consisted of 555 705 patients, of whom 185 625 (33.4%) underwent mammography. After adjusting for patient demographics, comorbidities, geographic covariates, and baseline preventive care, women who underwent index screening mammography (with either positive or negative results) were more likely than unscreened women to later undergo Papanicolaou test (odds ratio [OR], 1.49; 95% confidence interval: 1.40, 1.58), bone mass measurement (OR, 1.70; 95% confidence interval: 1.63, 1.78), and influenza vaccine (OR, 1.45; 95% confidence interval: 1.37, 1.53). In women who had not undergone these preventive measures in the 2 years before screening mammography, use of these three services after false-positive findings at screening was no different than after true-negative findings at screening. Conclusion In beneficiaries of U.S. Medicare, use of screening mammography was associated with higher likelihood of adherence to other preventive guidelines, without a negative association between false-positive results and cervical cancer screening.