Around 1 in 5 breast cancer survivors who have undergone 5 years of therapy experience cancer recurrence within the following 10 years, according to a 2008 study. Now, researchers from the Johns Hopkins Kimmel Cancer Center in Baltimore, MD, have created a blood test that they say can detect breast cancer recurrence with up to 95% accuracy and help monitor a patient's response to treatment.
The research team, led by Saraswati Sukumar, the Barbara B. Rubenstein professor of oncology and co-director of the Breast Cancer Program at the Johns Hopkins Kimmel Cancer Center, recently published their findings in the journal Cancer Research.
After a breast cancer patient has been treated successfully, their risk of recurrence is measured by standard blood tests and imaging, according to Sukumar. But these tests are generally only initiated if a patient complains of symptoms, such as pain, shortness of breath or bone aches.
If a patient is asymptomatic, routine blood tests and scans can produce false positives. The researchers say this can lead to unnecessary tests and biopsies.
With these factors in mind, the research team wanted to develop a non-invasive test that could detect breast cancer recurrence earlier and more accurately than current methods, and that could be administered routinely during doctors' visits.
Blood test detects hypermethylation in breast cancer genes
The team developed a test called the cMethDNA assay, which can monitor 10 breast cancer-specific genes in patients' blood.
To identify these genes, Sukumar and colleagues scanned the genomes of patients in the early stages of breast cancer. They also scanned the DNA of blood from patients with metastatic breast cancer.
From this, they found 10 genes that are specifically altered in breast cancers. These included seven genetic markers that had been newly identified, but which the team had previously associated with primary breast cancers.
To see whether a patient is at risk for breast cancer recurrence, the test determines whether hypermethylation - a process that silences genes that keep cancers in check - has occurred in any of the breast cancer genes. Signs of hypermethylation in the breast cancer genes indicate that the cancer is likely to recur.
Test 'determines cancer treatment response as early as 2 weeks'
To test the accuracy of the cMethDNA assay, the researchers conducted a series of experiments.
For one experiment, the researchers took 24 blood samples from patients with recurrent stage IV breast cancer and 28 blood samples from healthy women without breast cancer.
In distinguishing patients with metastatic breast cancer from healthy women without the disease, the team found the blood test was 95% accurate. This level of accuracy remained when the team conducted similar tests.
To see how accurate the test is in monitoring treatment response, the researchers assessed 58 blood samples of 29 patients with metastatic breast cancer. Some of these samples were taken prior to initiation of chemotherapy, while others were taken 18 to 49 days after a new chemotherapy regimen.
The test was able to determine patients' response to treatment as early as 2 weeks. At this point, it detected a decrease in DNA methylation in patients who were responding well to treatment or whose cancer had stabilized, while patients whose disease progressed or who did not respond to treatment did not show a reduction in DNA methylation.
Commenting on the findings, Sukumar says:
"Using cMethDNA, we were able to detect a drop in methylation levels as early as 2 weeks, and weeks before traditional imaging methods can detect a recurrence.
Detecting early on whether or not the treatment is working for a patient can greatly help prevent unnecessary exposure to highly toxic agents, save time and help initiate other treatments more likely to be beneficial."
In addition, the researchers tested the 10 genes used in the cMethDNA assay against samples from The Cancer Genome Atlas - a project that catalogues genetic mutations known to be responsible for cancer.
From this, they found that the cMethDNA assay could also be used to detect recurrent lung and colorectal cancers.
However, Sukumar notes that, although there is a patent pending on the test, further research is warranted to validate their findings and compare the test's accuracy against imaging tests currently used in standard practice.
Sukumar told Medical News Today that the team has already conducted a further study, which involved testing blood samples from 140 breast cancer patients at 2-weekly intervals.
The researchers wanted to see how well the cMethDNA assay predicted metastatic breast cancer and whether it can effectively trace the course of the disease. She told us the data has been collected and analysis is ongoing.
"Based upon the data obtained in the 140 patient study, we will participate in a large 600 woman national trial testing a new therapy for breast cancer," she added. "There, blood collections before, during and after treatment will be tested by cMethDNA to determine if the test can predict response to treatment weeks ahead of assessing response by imaging."
Medical News Today recently reported on a study from the Salk Institute in La Jolla, CA, in which researchers claim they have discovered a link between brain development and the BRCA1 breast cancer gene.