The study reviewed here suggests that a new way to measure heart damage caused by certain breast cancer treatments may find damage earlier than traditional tests.
The new measurement is longitudinal strain and it's measured by a heart ultrasound.
Using a heart ultrasound to measure longitudinal strain is considered experimental and most doctors who read echocardiograms have little experience with the technique.
In this study, the researchers also looked at high-sensitivity troponin 1 levels in blood samples to check for heart damage. While troponin testing isn't done routinely, some cancer centers monitor the troponin levels of people receiving certain chemotherapy medicines to determine if the medicines are causing heart problems.
Herceptin (chemical name: trastuzumab) is a targeted therapy used to treat advanced-stage, HER2-positive breast cancer and to lower the risk of recurrence of early-stage, HER2-positive breast cancer with a high risk of recurrence. HER2-positive cancers make too much of the HER2 protein. The HER2 protein sits on the surface of cancer cells and receives signals that tell the cancer to grow and spread. About one out of every four breast cancers is HER2-positive. Herceptin works by attaching to the HER2 protein and blocking it from receiving growth signals.
Herceptin may cause serious side effects, including heart damage that can lead to heart failure. Still, most patients don't have serious heart problems while getting Herceptin. And even if heart problems do develop, medicines can help improve heart function and the heart can repair itself over time.
The chemotherapy medicines:
are anthracyclines. These medicines often are used to treat advanced-stage breast cancer, as well as to reduce the risk of early-stage breast cancer coming back (recurring).
Like all chemotherapy medicines, anthracyclines can cause serious side effects. Anthracyclines may cause heart damage that can lead to heart failure. Still, limiting the amount of an anthracycline chemotherapy medicine used can help avoid serious heart problems.
Anthracycline chemotherapy medicines sometimes are used together with Herceptin to treat HER2-positive breast cancer.
Doctors typically check heart function at the beginning, during, and after treatment with either an anthracycline chemotherapy medicine or Herceptin. The heart function test result is called an ejection fraction. The ejection fraction is a measure of how effectively the heart is pumping. Unfortunately, if the ejection fraction is reduced, the heart may already be damaged from treatment.
In this study, 43 women diagnosed with HER2-positive breast cancer were treated with an anthracycline chemotherapy medicine plus Herceptin or an anthracycline chemotherapy and then Herceptin.
All the women had standard ejection fraction testing during treatment. The researchers also measured the women's longitudinal strain and high-sensitivity troponin 1 levels at the start of anthracycline treatment, then 3 months after anthracycline treatment started, and again 6 months later when the anthracycline treatment ended and Herceptin treatment was going to start.
Women who had a 10% increase in longitudinal strain 3 months after treatment started were 500 times more likely to have serious heart problems later.
About 66% of the women who were later diagnosed with serious heart problems had elevated troponin levels 3 months after treatment.
The results suggest that measuring longitudinal strain and troponin levels can help figure out if heart problems are starting to develop much earlier than traditional ejection fraction testing. Knowing earlier that heart problems are developing could help doctors adjust the treatment plan to avoid further damage.
If you've been diagnosed with breast cancer and an anthracycline chemotherapy medicine and/or Herceptin are part of your treatment plan, talk to your doctor about how your heart health will be monitored during treatment. You also may want to ask how your treatment plan will be changed if you do develop heart problems. While longitudinal strain testing is considered experimental, many doctors do check troponin levels to detect heart problems early. You may want to ask if checking troponin levels makes sense for you.
Reading about serious treatment side effects such as heart problems can be understandably scary. Still, you need to make sure you're getting the care that is best for YOU. You can learn more about coping with fears about side effects and treatment on the Breastcancer.org Dealing With Chemotherapy Fears page.
Please help Breastcancer.org bring you the latest news on managing treatment side effects by making a tax-deductible donation today.
SAN DIEGO (MedPage Today) -- A new way of measuring cardiac damage with electrocardiography could help detect early heart damage during treatment for breast cancer, researchers reported here.
In a small study among breast cancer patients, a decrease in longitudinal strain measured on echocardiography at three months predicted cardiotoxicity of anthracycline and trastuzumab (Herceptin) treatment (P=0.01) before any significant changes appeared in tests for left ventricular ejection fraction, according to a study led by Heloisa Sawaya, MD, PhD, of Massachusetts General Hospital and Harvard in Boston.
The other cardiac marker thought to be sensitive for early heart damage -- high-sensitivity troponin 1 -- also significantly predicted cardiotoxicity at six months (P=0.006), the researchers reported at the American Society of Echocardiography meeting here.
These effects persisted in a multivariate analysis, Sawaya told meeting attendees, and "represent sensitive indices of cardiac injury that could help guide clinicians in optimizing chemotherapy."
Early detection and prediction of cardiac damage may allow oncologists to switch to a less cardiotoxic regimen, lower the chemotherapy dose, or initiate prophylactic cardioprotective medications, Sawaya noted.
Left ventricular ejection fraction, although useful in detecting heart damage, may not detect it at an early enough stage to allow any form of intervention, she said.
However, longer follow-up is needed to determine if these tests also predict long-term heart failure and other cardiac events, Sawaya cautioned.
High-sensitivity troponin is already part of cardiac monitoring for breast cancer patients undergoing certain chemotherapy regimens, but longitudinal strain measured with echocardiography is a newer measurement still proving itself.
Longitudinal strain is a measure of the intrinsic strength of the heart muscles, how much the muscles contract in a beat, explained meeting program chair Vera Rigolin, MD, of Northwestern University in Chicago, who was not involved in the study.
These "exciting" results affirm that longitudinal strain is a very sensitive method that predicts early changes in heart function as expected, Rigolin said.
"The fact that it is confirming what we hoped has treatment implications for millions of women," she said in an interview with MedPage Today. "The use of this [test] is probably going to expand."
Because of previous indications of benefit for early cardiac testing, Sawaya's group conducted a study in 43 adult patients with HER2 overexpressing breast cancer undergoing treatment with anthracycline chemotherapy plus trastuzumab or trastuzumab after prior anthracycline; none had a baseline ventricular ejection fraction of less than 50% of that expected.
Patients got an echocardiogram and gave a blood sample at baseline (when starting anthracycline), then had the same set of tests at three months before starting trastuzumab, and at concurrent taxane treatment, then at six months before they went on to trastuzumab treatment alone every three weeks.
Cardiotoxicity -- defined as at least a 5% reduction in ejection fraction to under 55% with symptoms of heart failure or an asymptomatic reduction of ejection fraction of at least 10% to less than 55% -- was associated with the change in ejection fraction at three months, but this factor was not significantly predictive (P=0.19).
Longitudinal strain changed by 15% at three months on average in patients who later developed cardiotoxicity compared with 3% in patients without cardiotoxicity (P=0.01). Patients who had a 10% change in longitudinal strain by three months had an odds ratio of 500 for cardiotoxicity.
Radial strain at three months likewise predicted later cardiotoxicity (change 22% versus 2% no cardiotoxicity, P=0.02 for prediction).
Change in N-terminal pro B type natriuretic peptide (NT-proBNP) at three months was not predictive (P=0.91).
High-sensitivity troponin 1 -- also thought to be highly-sensitive for early cardiac damage in breast cancer patients -- became elevated to more than 0.015 μg/L by three months in 67% of women who developed cardiotoxicity, compared with 18% in those who didn't, making it a significant predictor of cardiotoxicity (P=0.006).
A 100% rise in high-sensitivity troponin predicted a nine-fold increase in cardiotoxicity risk.
The accuracy of prediction with a 10% decrease in longitudinal strain had 50% positive predictive value and 93% negative predictive value while elevated troponin at three months came in at 50% and 90%, respectively.
Together, the two had 55% sensitivity, 97% specificity, 83% positive predictive value, and 89% negative predictive value.
Rigolin cautioned that longitudinal strain is an echocardiography method not yet mainstream in community practice, with neither the experience to read the images nor the software to do so commonly available outside the research setting.
"It's still in its infancy," she said.
The researchers reported having recieved an Claflin Distinguished Scholar Award and a grant from the Susan G. Komen for the Cure Foundation as well as a Kynett Focus Junior Faculty Investigator Award. Sawaya's coauthors reported conflicts of interest with Roche, Siemens, GE, and Critical Diagnostics.
Rigolin reported no relevant conflicts of interest.
Primary source: American Society of Echocardiography meeting Source reference: Sawaya H, et al "Early Detection and Prediction of Cardiotoxicity in Chemotherapy-Treated Patients: An Echocardiographic and Biomarker Study" ASE 2010; Abstract P1-42.
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