Cancer Sample Handling Changes Called For By Doctors

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In a column appearing this week in the Journal of the American Medical Association (JAMA), doctors have called on the medical community to change the way it handles cancer tissue samples. At issue is the rise of new gene sequencing technology, which traditional sample handling practices impede by damaging DNA.

"Deciding how best to obtain (tumor) samples and how best to process them for whole genome or exome sequencing is a pivotal yet unresolved issue with several layers of complexity," said the column's authors, who are from the Scripps Translational Science Institute (STSI), a non-profit biomedical research organization. "As the new clinical applicability of genomics emerges at a fairly rapid rate, the field of pathology will arrive at a tipping point for a fundamental change in how cancer specimens are handled."

The current methods for sample processing involve placing biopsy samples into a formaldehyde mixture called formalin, then placing them into paraffin. Using gene sequencing on samples prepared this way, say the doctors, is difficult because the chemicals involved damage the sample's DNA.

"We need to completely rethink the way we have collected and stored cancer tissue samples for decades," said Dr. Eric Topol, one of the column's authors and director of STSI. "It's becoming increasingly clear that obtaining an accurate map of a tumor's DNA can be the key to determining the specific mutations that are driving a person's cancer, how best to treat it and how likely it is to recur."

The alternative the doctors recommend involves freezing a portion of samples, which preserves the tissue's genetic coding. That procedure, however, would require larger biopsy samples and incur higher storage costs. The doctors point out, though, that patients would likely agree to more invasive biopsy procedures if it means better diagnosis and treatment.

"This type of change will require discussion about new operative standards, which will need the cooperation of surgeons, pathologists, ethicists and, of course, appropriate patient consents," said Dr. Stanley Robboy, president of the College of American Pathologists. "It's these types of implications we will need to consider and incorporate as a progressive healthcare agenda is moved forward."

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