A new study published in the British Medical Journal is reigniting the debate over mammography as a screening tool. Lead author Dr. Phillipe Autier looked at historical data from 1980 to 2006 to determine the impact of screening mammography on breast cancer-related mortality in six European countries. The greatest decrease in mortality over this 26 year period was seen in women ages 40 to 49. However, there was not a correlation between decreases in mortality and the availability of screening mammography in these countries. Accordingly, the authors have concluded that there is no impact on breast cancer mortality as a result of screening mammography. Rather, the authors infer that improved treatments for breast cancer and efficiencies in healthcare are more likely responsible for this decrease.
This and other studies published on the efficacy of screening mammography seem at odds with new recommendations from the American College of Obstetrics and Gynecology (ACOG). This week, ACOG released updated guidelines recommending screening mammography annually for all women over 40. ACOG revised its earlier recommendations of annual screening at 50 due to new evidence that more aggressive tumors have shorter sojourn times (time from detection to symptoms) in women under 50, and that reductions in mortality due to screening are similar for women in their 40s and 50s. ACOG emphasizes the importance of communicating the risk of false positives to women receiving screening mammography as this risk increases with more frequent imaging. This high false positive rate is also referenced in the widely-discussed USPSTF guidelines from 2009 that recommend biennial screening at age 50.
This issue is likely to lead to increasing consumer confusion regarding the effectiveness in screening mammography at lowering the rate of mortality for breast cancer. Therefore, it is imperative that providers are open about the risk of false positive exams with patients. While many in the radiology community are concerned about the number of unnecessary exams, ACOG notes that many patients are aware of this risk and are well-adept at coping with anxiety that results from biopsies and other downstream procedures.
Alternatively, using more specific screening technology, such as tomosynthesis, may help to decrease breast cancer-related mortality. Some radiologists suggest using breast MRI to screen for all patients, though it is already plagued by a high false positive rate and will be prohibitively expensive for many providers (and payers). Tomosynthesis promises to improve on the recall rate from screening mammography though it is not yet clear if this will reduce the number of breast cancer related deaths over a long period of time.
As vendors release new products and upgrades to existing technology it will become increasingly difficult to determine the relative effectiveness of each product. Research cannot keep pace with innovation so it will be left to individual physicians and hospitals to determine the relative merits of each new tool.
Technology Insights is continuing to track the screening mammography pipeline to provide up-to-date guidance on right-fit investments in the ever-changing breast imaging market.
In light of recent incidences of excessive radiation exposure, the FDA has issued an advisory to medical imaging providers to discontinue use of the CardioGen-82 rubidium isotope generator for myocardial PET imaging studies. The CardioGen-82 rubidium chloride injection generator has since been voluntarily recalled by the vendor, Bracco Diagnostics.
This news comes on the heels of recent reports and a public advisory issued by the FDA regarding two incidences of patients receiving radiation exposures in excess of expected thresholds when using the CardioGen-82 generator for myocardial PET imaging studies. According to the FDA's announcements, and coverage in trade websites Health Imaging and AuntMinnie, the risks associated with the excessive exposure are expected to be minimal and on par with cumulative exposure from other cardiac imaging studies; the two patient exposures are estimated to be approximately 90 mSv - approximately 30 times the average exposure for CardioGen-82 myocardial PET imaging procedures. Given the FDA's determination the manufacturing procedures for the CardioGen-82 generator are not sufficient for ensuring the "reliable performance of the generator used to produce the Rb-82 chloride injection," the vendor, Bracco Diagnostics, has since voluntarily recalled the CardioGen-82 generator, and is actively working with the FDA and regulatory agencies to determine the exact cause of the excessive exposure. However, questions still linger regarding whether the excessive exposures are the result of a manufacturing flaw or appropriate quality control techniques at clinical sites using the Rb-82 chloride injection system. In the interim, providers are encouraged to use alternative isotopes or different cardiac imaging studies when clinically appropriate. In a July 15 advisory when the incidences were first identified, the FDA presents a detailed description of steps patients and providers should take in determining and mitigating potential risks associated with CardioGen-82 use.
This comes as a roadblock to the use of myocardial PET imaging for perfusion and viability imaging, which has received a considerable amount of attention over the past 18 months. Rubidium-82 is the principal radiotracer used to evaluate myocardial perfusion with PET. Evidence of superior clinical efficacy for obese patients relative to traditional cardiac nuclear imaging, as well as growing coverage for the use of cardiac PET following equivocal SPECT studies, has led to greater awareness of the value of cardiac PET imaging. But, interest and adoption in cardiac PET has been spurred by market factors, including declining reimbursement for cardiac nuclear imaging (particularly office-based procedures), the worldwide technetium radioisotope shortage, and greater desire to maximize the use of hospital-based PET/CT scanners.
Previously, cardiac PET imaging has been slow to develop given the entrenched practice patterns of cardiologists with standard cardiac nuclear imaging, fluctuating reimbursement, and the hefty price tags associated with monthly rental of the rubidium-82 generator - often upwards of $25,000 - rendering breakeven on the investment challenging. Further, adoption of cardiac PET can both generate new procedure volume and cannibalize from existing cardiac nuclear imaging studies, rendering it a strategic, programmatic investment for hospitals to support comprehensive cardiovascular services.
At this time, it is unclear when the FDA and Bracco Diagnostics will lift the recall of the CardioGen-82 generator system. Providers are encouraged to stay tuned to new developments and communications from the vendor and the FDA regarding future use for Rb-82 PET imaging.
After a unanimous panel vote, the Berlin Heart Excor Pediatric VAD is expected to receive humanitarian device exemption (HDE) from the FDA. This technology--a bridge-to-transplant, pneumatic blood pumping ventricular assist device intended for use in children with isolated left ventricular or biventricular dysfunction--is currently the only option for patients with severe heart failure (HF) who are awaiting transplant. The Berlin Heart can provide children with extended time before a needed heart transplant, thereby decreasing mortality rate and increasing survival rate.
In the device's trial, 48 patients age 16 or younger received either the Excor or extracorporeal membrane oxygenation (ECMO), the standard of care at present for pediatric patients awaiting a heart transplant. While ECMO patients demonstrated between 66 and 75 percent survival rates depending on cohort (as determined by body surface area), Excor patients showed survival rates between 86 and 92 percents. These dramatic differences between groups led panelists to vote in favor of the Berlin Heart VAD despite significant adverse event rates among these patients: adverse events such as bleeding incidents or infections occurred in 85 percent of study patients overall, and nearly 30 percent suffered a stroke.
Nevertheless, when compared to current therapy, FDA members agreed that these risks were worth the added benefit to survival. Devices such as the Berlin Heart Excor--the only option of their kind--can significantly improve pediatric cardiology treatment, given that the average wait for a heart transplant can exceed four months and the current ECMO survival timeframe is only two weeks. While further, targeted studies are needed for this technology, panelists are hopeful for its potential to impact pediatric survival and mortality.