Accuracy depends on number of mammograms read

Suleiman et al report in the Journal of Medical Imaging, the effect the number of screening mammograms read per year has on the performance of expert radiologists from Australia and the United States in the detection of breast cancer.

Forty-one radiologists, 21 from Australia and 20 from the United States, reviewed 30 mammographic cases.  Twenty cases were abnormal while 10 cases were normal mammograms. Radiologists were asked to locate malignancies and assign a level of confidence. A jackknife free-response receiver operating characteristic, figure of merit (JAFROC, FOM), inferred receiver operating characteristic, area under curve (ROC, AUC), specificity, sensitivity, and location sensitivity were calculated using Ziltron software and JAFROC v4.1. A Mann-Whitney U test was used to compare the performance of Australian and U.S. radiologists.

The results showed that when radiologists’ experience and number of mammograms were reading per year were taken into account, the Australian radiologists sampled showed significantly higher sensitivity and location sensitivity while JAFROC (FOM) and inferred ROC (AUC) analyses showed no difference between the overall performance in the two countries. Receiver operating characteristic and location sensitivity were higher for the Australian radiologists who read the most cases per year.

Radiologists perform better at screening if they follow up with diagnostic mammograms

Buist et al in their Radiology article analyzed the performance of 96 radiologists at screening mammograms (651 671).  They looked at the effect the number of diagnostic work-ups performed after abnormal findings were found at screening had if the same or a different radiologist interpreted them.

Annually, 38% of radiologists performed the diagnostic work-up for 25 or fewer of their own recalled screening mammograms, 24% for 0–50, and 39% for more than 50. For the work-up of recalled screening mammograms from other radiologists, 24% of radiologists performed the work-up for 0–50 mammograms, 32% performed the work-up for 51–125, and 44% performed the work-up for more than 125.

With increasing numbers of radiologist work-ups for their own recalled mammograms, the sensitivity of screening mammography increased, yielding a stepped increase in women recalled per cancer detected from 17.4 for 25 or fewer mammograms to 24.6 for more than 50 mammograms. Increases in work-ups for any radiologist yielded significant increases in false positive rate and cancer detection rate and a non-significant increase in sensitivity. Radiologists with a lower annual volume of any work-ups had consistently lower false positive rate, sensitivity, and cancer detection rate at all annual interpretive volumes.

They conclude that radiologists may improve their screening accuracy by performing diagnostic work-up for their own recalled screening mammograms.  They recommend arranging for radiologists to work up a minimum number of their own recalled cases in order to improve their accuracy in screening.

CT Screening for Lung Cancer may be Cost-Effective

Black et al in their article published by the NEJM report that findings from the National Lung Screening Trial, that was funded by the NCI, showed that screening with low-dose computed tomography as compared with chest radiography reduced lung-cancer mortality.

Their research team estimated mean life-years, quality-adjusted life-years (QALYs), costs per person, and incremental cost-effectiveness ratios (ICERs) for three alternative strategies: screening with low-dose CT, screening with radiography, and no screening. Estimations of life-years were based on the number of observed deaths that occurred during the trial and the projected survival of persons who were alive at the end of the trial. Quality adjustments were derived from a subgroup of participants who were selected to complete quality-of-life surveys. Costs were based on utilization rates and Medicare reimbursements. They also performed analyses of subgroups defined according to age, sex, smoking history, and risk of lung cancer and performed sensitivity analyses based on several assumptions.

As compared with no screening, screening with low-dose CT costs an additional $1,631 per person and provided an additional 0.0316 life-years per person and 0.0201 QALYs per person. The corresponding ICERs were $52,000 per life-year gained and $81,000 per QALY gained. However, the ICERs varied widely in subgroup and sensitivity analyses.

They concluded that screening for lung cancer with low-dose CT would cost $81,000 per QALY gained.  They also determined that modest changes in their assumptions would greatly alter this figure. The determination of whether screening outside the trial will be cost-effective will depend on how screening is implemented.

References

1.  Updating Cost-Effectiveness — The Curious Resilience of the $50,000-per-QALY Threshold.  Peter J. Neumann, Sc.D., et al N Engl J Med 2014; 371:796-797August 28, 2014  http://www.nejm.org/doi/full/10.1056/NEJMp1405158
2.  On November 11, 2014 the U.S. Centers for Medicare and Medicaid Services (CMS) approved CT lung cancer screening for Medicare recipients, saying the evidence is sufficient to justify screening high-risk individuals until the age of 74 years.

Tomosynthesis could be cost-effective for Breast Cancer Detection

Lee at al in their article in Radiology report on the effectiveness of combined biennial digital mammography and tomosynthesis, compared with biennial digital mammography alone to screen women aged 50-74 with dense breasts for breast cancer.

For the base-case analysis, the incremental cost per quality-adjusted life year gained by adding tomosynthesis to digital mammography screening was $53 893. An additional 0.5 deaths were averted and 405 false-positive findings avoided per 1000 women after 12 rounds of screening. Combined screening remained cost-effective (less than $100 000 per quality-adjusted life year gained) over a wide range of incremental improvements in test performance. Overall, cost-effectiveness was most sensitive to the additional cost of tomosynthesis.

Biennial combined digital mammography and tomosynthesis screening for U.S. women aged 50–74 years with dense breasts is likely to be cost-effective if priced appropriately (up to $226 for combined examinations versus $139 for digital mammography alone) and if the reported interpretive performance metrics of improved specificity with tomosynthesis are met in routine practice.

They concluded biennial digital mammography combined with tomosynthesis screening for women aged 50–74 years with dense breasts is likely to be cost-effective if priced appropriately (up to $226 for combined examinations versus $139 for digital mammography alone) and if specificity reported from tomosynthesis is achieved among the many practices across the country.