WEDNESDAY, March 23 (HealthDay News) -- Scientists may have
developed a new way of predicting when breast cancer will
Two varieties of what scientists call "epigenetic signatures"
seem to distinguish more aggressive cancers from less aggressive
ones, according to a new study.
Epigenetic alterations do not involve changes to the sequencing
of the genes themselves. Instead, they involve alterations in the
outer wrapping that holds genes within the chromosome. This
chromosomal casing helps determine whether the genes will activate
and at what intensity.
Environmental factors, including diet, stress, illness or
environmental pollutants can all influence epigenetics, experts
The findings could not only lead someday to a new diagnostic
screening tool to parse out more aggressive cancers that might
benefit from more aggressive treatment, but could also "open the
door for new physiological targets" for therapies, explained Dr.
Timothy A. Chan, senior author of a paper appearing March 23 in the
Science Translational Medicine.
It's also not out of the question that modifiable environmental
factors might be identified that contribute to the cancers, Chan
How to tell if a particular tumor will spread (metastasize), and
then finding ways to prevent that are major goals of the
researchers. Patients usually die from a cancer that has
metastasized, not from localized tumors.
This international consortium of researchers collected a variety
of different types of breast cancers -- some were hormone
receptor-positive, some negative, some had spread and some had not
-- then analyzed their methylation profiles.
Methylation refers to the epigenetic "marks" left on the
"To our surprise, we noted that there appear to be two main epigenomic subgroups," said Chan, who is a lab head and attending physician at Memorial Sloan-Kettering Cancer Center in New York City.
This was a surprise because scientists have identified myriad
different types of breast cancers based on their genetics and other
In this case, one group showed high methylation and one showed
The high-methylation group "tended to be pretty stable at the
genomic level and were composed primarily of hormone-positive
cancers," Chan said. "The [low-methylation] group includes all the
hormone-negative group and about half of hormone-positive
And women with high-methylation tumors did much better than the
other group, independent of their hormone-receptor status.
The team is now working on a test to distinguish the two
epigenetic types and are investigating what drives these changes,
which have also been observed in colon cancer and the deadly brain
"What we're probably looking at is some fundamental process that becomes dysregulated and helps drive the cancers," Chan said.
"This [study] allows us to further subset breast cancers into those that are likely to metastasize and those that aren't likely to metastasize, and that's helpful," noted one expert, Dr. Patrick Borgen, chairman of the department of surgery at Maimonides Medical Center in New York City.
But, Borgen cautioned, "the technology that [does this
categorization] is far from the grasp of day-to-day clinicians.
[The study is] an important foundation for further research."
Learn more about epigenetics at the
University of Utah.