New test predicts if breast cancer will spread
The study was led by researchers at the National Cancer Institute (NCI) - designated Albert Einstein Cancer Center of Albert Einstein College of Medicine of Yeshiva University and Montefiore Einstein Center for Cancer Care and was published online today in the Journal of the National Cancer Institute (JNCI).
“Tests assessing metastatic risk can help doctors identify which patients should receive aggressive therapy and which patients should be spared,” said Thomas Rohan, M.D., Ph.D., the lead and corresponding author of the study and professor and chair of epidemiology & population health at Einstein and Montefiore.
To measure the test’s effectiveness, the researchers used it on about 500 breast tumor specimens that had been collected over a 20-year period. The test proved more accurate in predicting the risk of distant tumor spread than a test closely resembling the leading breast cancer prognostic indicator on the market.
According to the NCI, 232,340 American women developed breast cancer last year and 39,620 women died from the disease. It is the most common cancer among women in the United States. Death from breast cancer is mainly due to distant metastasis, when cancer cells in the primary tumor invade blood vessels and travel via the bloodstream to form tumors elsewhere in the body.
Observing How Cancer Cells Metastasize
“Currently marketed tests assess risk for breast cancer metastasis by looking for changes in gene expression or in levels of proteins associated with growth of tumor cells,” said Joan Jones, M.D., senior author of the JNCI paper, professor of pathology of anatomy and structural biology and of epidemiology & population health at Einstein and attending pathologist at Montefiore Medical Center. “But those changes don’t reflect the mechanism by which individual tumor cells invade blood vessels, a necessary step for metastasis. By contrast, our test is based on what Einstein researchers learned from intravital imaging, which reveals biological processes deep within the tissues of a living animal. Using this technology, they determined how breast cancer tumor cells spread in rodents.”
Those observations showed that primary breast cancers metastasize when a specific trio of cells is present together in the same microanatomic site: an endothelial cell (a type of cell that lines the blood vessels), a perivascular macrophage (a type of immune cell found near blood vessels) and a tumor cell that produces high levels of Mena, a protein that enhances a cancer cell’s ability to spread. A site where these three cells touch is where tumor cells can enter blood vessels. That site is called a tumor microenvironment of metastasis, or TMEM.
Where in the body does breast cancer usually spread?
The most common sites for breast cancer to spread (and methods for localized treatment) are:
Lymph nodes Under the arm (or axilla, called axillary nodes) or along the center of the rib cage (internal mammary nodes) or near the collar bone (supraclavicular nodes).
Muscle, fatty tissue and skin – usually in the area near where the initial tumor was, for example the muscles of the chest wall or on the surgical scar. Breast cancer that spreads only to these areas may have a somewhat better prognosis—if it has spread through direct extension through tissue surrounding the original cancer, or through the lymphatic system, and not through the circulatory system. While sometimes removed surgically or subjected to radiation treatment, these metastatic sites often (but not invariably) will turn out to be early indicators of widespread metastatic disease. The main treatment is usually systemic, therefore, in an attempt to delay the spread of the cancer to distant metastatic sites.
Bones – breast cancer can spread to many parts of the skeleton, but the ribs, spine, pelvis and long bones of the arms and legs are the most common metastatic sites. Persistent pain, achiness, or tenderness on pressure are usually the first symptom of bone metastases. Bone metastases are of two kinds, or may have mixed features. Osteolytic bone metastases, where the bone is eaten away, have a characteristic “Swiss cheese” appearance on scans, and may cause weakening and even fracture of weight-bearing bones, although this is less common now that IV bisphosphonates are routinely given. Osteoblastic bone metastases can cause growth of unhealthy bone that leads to pain. Less commonly, numbness or problems with bowel or bladder control can be a sign that bone metastases are causing spinal cord compression. This should be considered a medical emergency, since this can lead to permanent loss of function. Immediate focalized radiation or surgery is usually required.
Bone marrow - cancer cells in the bone marrow are often present with metastatic breast cancer, especially when there are bone metastases, but may go undetected until there is a significant and growing decrease in white or red cell counts that is unrelated to lowered counts from chemotherapy. A finding like this may lead an oncology to order a bone marrow biopsy, which can confirm the diagnosis. For these patients, a delicate balance that must be struck with effective chemotherapy drugs to control bone marrow metastases that at the same time depress the bone marrow.
Dr. Jones, who is also director of clinical imaging applications in Einstein’s Integrated Imaging Program (IIP), led a team of pathologists who applied the intravital imaging observations in living rodents to identify TMEMs in human breast biopsy specimens. The scientists developed a test that uses a triple immunostain containing antibodies to the three cell types that make up a TMEM. The test was then optimized using resources in the IIP, established with the support of benefactor Evelyn Gruss Lipper, M.D., an Einstein alumna (‘71) and honorary Einstein Overseer.
The IIP combines the attributes of several different imaging technologies to reveal in great detail how cancer and other complex diseases get started and progress in the body, permitting the translation of basic-science observations into relevant clinical applications. The pioneering intravital imaging that made these discoveries possible was developed in the Gruss Lipper Biophotonics Center at Einstein.
Assessing Risk in Breast Cancer Patients
The JNCI paper describes results from a case-control study that evaluated tumor samples from a subset of women in the Kaiser Permanente Northwest health plan who were diagnosed with invasive ductal carcinoma of the breast between 1980 and 2000. TMEM testing was carried out on specimens from 259 women who later developed a distant metastasis (the cases) and on specimens from women who were alive and had not developed a distant metastasis (the controls). Controls were individually matched with cases so that women in each pair were the same age and were diagnosed with breast cancer in the same year. The pathology team applied the triple immunostain to specimens and counted the TMEMs. The team members did not know whether the specimens came from breast tumors that remained localized or from those that had metastasized to distant sites. The final TMEM score for each specimen was calculated by counting the total number of TMEMs observed within ten 400x magnification fields.
The TMEM test performed well at assessing metastatic risk for the study’s most populous cancer subgroup: women with estrogen receptor positive/HER2- disease (i.e., their cancer cells possess estrogen receptors but lack HER2 protein). Women with estrogen receptor positive/HER2- disease account for about 60 percent of all cases of breast cancer. When women with this common type of breast cancer were divided into three groups based on the distribution of TMEM scores in the control group, the risk of distant metastasis turned out to be 2.7 times higher for women with tumors in the high-score TMEM group compared with women with tumors in the low-score TMEM group.
For comparison, all tumor specimens included in the study were also analyzed by the IHC4 test. This previously validated test assesses metastatic risk by measuring levels of several proteins in breast-tumor tissue. The IHC4 test is known to provide prognostic information comparable to the Oncotype DX test—a gene-expression test that is the most commonly used test for calculating metastatic risk in breast tumors.
Significant Findings
Overall, there was little agreement between the TMEM test and the IHC4 test regarding prediction of metastatic risk. As for assessing metastatic risk in the study’s most common type of breast cancer (ER+/HER2-), TMEM results were highly statistically significant while IHC4 scores were borderline significant at best. The findings confirmed results from a smaller study of the TMEM test (involving 30 pairs of tumor specimens) that was published by researchers from Einstein and other institutions in 2009.
“This assay could eventually reduce overtreatment of early stage breast cancer, which remains a major problem despite extensive use of other prognostic assays,” added study co-author Joseph Sparano, M.D., associate director for clinical research at the Albert Einstein Cancer Center, professor in the departments of medicine (oncology) and of obstetrics & gynecology and women’s health at Einstein and vice chair of medical oncology, Montefiore Einstein Center for Cancer Care.
“We’re pleased we found a strong and statistically significant association between TMEM score and risk of metastasis in the most common type of breast cancer,” said Dr. Rohan, who is also associate director for population sciences and leader of the cancer epidemiology program at Albert Einstein Cancer Center and the Harold and Muriel Block Chair in Epidemiology & Population Health at Einstein. “Further studies will certainly be needed to validate our test, but our findings suggest that it might prove useful for guiding treatment decisions in women with breast cancer.”
The paper is titled “Tumor Microenvironment of Metastasis and Risk of Distant Metastasis of Breast Cancer.” Additional Einstein authors of the study are John Condeelis, Ph.D., Xiaonan Xue, Ph.D., and Mindy Ginsberg, B.A. Additional Einstein-Montefiore authors are Maja Oktay, M.D., Ph.D., and Joseph Sparano, M.D. Other authors are Hung-Mo Lin, Sc.D., of Mount Sinai School of Medicine; Frank B. Gertler, Ph.D., of the Massachusetts Institute of Technology; and Andrew G. Glass, M.D., of Kaiser Permanente Northwest.
The research was supported by MetaStat, Inc., a company that is developing a commercial TMEM test. MetaStat had no role in designing the study or writing the manuscript. Dr. Oktay is supported by NCI grant RO1 CA170507. Dr. Condeelis is supported by NCI grant PO1 CA 100324. Dr. Jones is supported by Einstein’s Integrated Imaging Program. Dr. Gertler is supported by NCI grant U54-CA112967. This work was also supported in part by Jane A. and Myles P. Dempsey.
The following authors affiliated with Einstein and/or Montefiore are shareholders in MetaStat and receive compensation as consultants to the company: Drs. Condeelis, Jones, Rohan and Sparano. Dr. Oktay is a consultant for MetaStat.
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About Albert Einstein College of Medicine of Yeshiva University
Albert Einstein College of Medicine of Yeshiva University is one of the nation’s premier centers for research, medical education and clinical investigation. During the 2013-2014 academic year, Einstein is home to 734 M.D. students, 236 Ph.D. students, 106 students in the combined M.D./Ph.D. program, and 353 postdoctoral research fellows. The College of Medicine has more than 2,000 full-time faculty members located on the main campus and at its clinical affiliates. In 2013, Einstein received more than $155 million in awards from the NIH. This includes the funding of major research centers at Einstein in diabetes, cancer, liver disease, and AIDS. Other areas where the College of Medicine is concentrating its efforts include developmental brain research, neuroscience, cardiac disease, and initiatives to reduce and eliminate ethnic and racial health disparities. Its partnership with Montefiore Medical Center, the University Hospital and academic medical center for Einstein, advances clinical and translational research to accelerate the pace at which new discoveries become the treatments and therapies that benefit patients. Through its extensive affiliation network involving Montefiore, Jacobi Medical Center -Einstein’s founding hospital, and five other hospital systems in the Bronx, Manhattan, Long Island and Brooklyn, Einstein runs one of the largest residency and fellowship training programs in the medical and dental professions in the United States.
About Montefiore Medical Center
As the University Hospital for Albert Einstein College of Medicine, Montefiore is a premier academic medical center nationally renowned for its clinical excellence, scientific discovery and commitment to its community. Recognized among the top hospitals nationally and regionally by U.S. News & World Report, Montefiore provides compassionate, patient- and family-centered care and educates the healthcare professionals of tomorrow. The Children’s Hospital at Montefiore is consistently named in U.S. News’ “America’s Best Children’s Hospitals.” With four hospitals, 1,491 beds and 90,000 annual admissions, Montefiore is an integrated health system seamlessly linked by advanced technology. State-of-the-art primary and specialty care is provided through a network of more than 130 locations across the region, including the largest school health program in the nation and a home health program. Montefiore’s partnership with Einstein advances clinical and translational research to accelerate the pace at which new discoveries become the treatments and therapies that benefit patients. The medical center derives its inspiration for excellence from its patients and community, and continues to be on the frontlines of developing innovative approaches to care.
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