Biopsies of tumors are automatically taken and examined by pathologists to
diagnose, treat and monitor cancers. But few laymen know that samples from
oncology patients – taken with their permission – can benefit research by
creating a biobank of cancerous tissue. A public tender that the Health Ministry
issued recently chose Hadassah University Medical Center in Jerusalem’s Ein
Kerem neighborhood, Rambam Medical Center in Haifa, Tel Aviv Sourasky Medical
Center and Sheba Medical Center to collect and house such tissue samples. For
the first time the institutions will share information, rather than each
hospital keeping it for its own researchers.
Dr. Karen Meir, head of the
Hadassah branch of the tissue bank, told The Jerusalem Post that the hospital
had been collecting samples in an informal way since 2008, but the idea of a
cancer tissue data bank had never really gotten off the ground. Fortunately
oncology researchers managed to persuade the ministry that the data was worth
saving and studying, and to finance the NIS 36 million project.
“A lot of
credit for initiating such tissue banking at the national level should go to
Nobel Prize [in chemistry] Laureate in Prof. Aaron Ciechanover of Haifa’s
Technion-Israel Institute of Technology,” she added.
With every sample
easily accessed and all running smoothly, said Meir, the process will become
much more efficient and make it easier for researchers to do their work.
Patients are clearly told that they personally are unlikely to benefit from the
“donation,” but that others eventually could, from improved understanding and
eventual treatment. Very few refuse, she said.
What the samples are used
for depends on the type of research, she continued. “Highquality specimens can
help find disease biomarkers or develop better tests or drugs.
Such
biobanks exist all over the world; European countries especially are investing a
lot in them. Israel is almost two decades behind in this field.”
The
location of the network’s coordinating headquarters has not yet been announced,
but the biobank in each of the four hospitals will need freezers, liquid
nitrogen tanks and a pathology archives.
“Security is a big factor. The
tissue will be under lock and key, as the donors do not want any personal
information to leak out,” Meir said, adding that “eventually, research into
other diseases – genetic, degenerative or chronic, from autism to Parkinson’s –
could benefit. The list is endless.”
VIRTUALLY, WITHOUT LAXATIVE Computed
tomographic colonography (CTC), also known as virtual colonoscopy, can be
performed without laxatives and still be as accurate as conventional colonoscopy
in detecting clinically significant, potentially cancerous polyps. That is the
finding of a new study performed jointly in California and Massachusetts and
published in the Annals of Internal Medicine. This is good news for patients,
radiologists and gastroenterologists alike.
“I think we have demonstrated
that laxative-free CTC is a valid tool for detecting polyps that are clinically
significant,” said co-author and radiologist Dr. Judy Yee of San Francisco VA
Medical Center.
Virtual colonoscopy, which the American Cancer Society
has approved as a valid screening test for colorectal cancer, uses a CT scanner
to screen for cancers and polyps in the colon non-invasively. In standard
optical colonoscopy (OC), a physician inserts a 2-meter-long scope into the
entire colon. Currently both methods call for patients to take a bowel-cleansing
laxative before the procedure.
With laxative-free CTC, explained Yee,
patients do not have to go through an enema before the exam, but instead begin a
low-fiber diet two days before the test. They also ingest a tagging agent the day
before the exam, which mixes with residual material in the colon and can then be
identified and removed digitally when radiologists interpret the
scans.
“The use of laxatives is often viewed as the worst aspect of
having not only a virtual colonoscopy but an optical colonoscopy,” said Yee, who
has pioneered the use of virtual colonoscopy within the VA health care system
and at UCSF. “I hope that this research will encourage patients who have delayed
screening for colon cancer to be examined with this less invasive
method.”
The study of 605 patients aged 50 to 85 assessed the accuracy of
laxative-free CTC in detecting lesions 6 millimeters or larger in size compared
with standard optical colonoscopy.
The authors found that laxative-free
CTC exams detected clinically significant polyps 10 mm. or larger with 91
percent accuracy compared to OC exams, which were 95% accurate.
Scan
sensitivity using laxative-free CT colonography decreases with polyp size, as it
does for regular CT colonography, she said. With polyps measuring 6 mm.,
sensitivity for CTC was 59%, compared with standard colonoscopy at
76%.
The smaller the polyp, the less likely it is to harbor malignancy.
For diminutive polyps 5 mm.
or less, there is an extremely low risk of
cancer, and these polyps may not need to be removed, she said.
“Polyps 10
millimeters or larger unquestionably come out,” she added.
During the
study, three of the 605 subjects were found to have cancerous polyps. The
cancers were identified by both the laxative-free virtual colonoscopy and the
standard OC exam. The researchers also found that patients much preferred the
laxative-free virtual colonoscopy technique.
Yee noted that her study was
one of the first and largest to measure the effectiveness of the new procedure,
although additional studies still need to be conducted. She predicts that once
radiologists are trained in reading the new images and gain experience with the
technique, laxative-free CTC exams will be available wherever virtual
colonoscopies are performed.