||Conquer Cancer Health News
Accurate Diagnosis Two New Tests Predict Cancer Outcome PET Scan denoting a patient whose tumor was eradicated. M. McManus (HO)
NEW ORLEANS - Two new
approaches to diagnosing cancer could save
many patients from needless surgery and better
predict whether patients are doomed to die of
the disease, doctors said today.
One approach uses positron emission tomography
(PET) scans to see if a tumor is still alive and spreading,
while another looks for the telltale proteins produced by
the most dangerous kinds of tumors.
Currently, doctors use X-rays and a souped-up X-ray
called a computed tomography, or CT, scan to diagnose
"CT gives a very good description of the shape and
structure of masses such as tumors, but it is no good at
telling what is going on in these structures," Dr. Michael
McManus of the Peter MacCallum Cancer Institute in
East Melbourne, Australia, told reporters.
"PET can see inside the mass."
Scanning Cell Activity
A PET scan looks at actual cell activity. Tumors use more
glucose than normal tissue, so radioactive glucose can be
given to a patient and then tracked using PET.
Two teams of researchers told a meeting of the
American Society of Clinical Oncology (ASCO) in New
Orleans about using PET scans to help lung cancer
McManus used PET scans on 56 lung cancer patients
whose tumors could not be removed surgically. They get
chemotherapy or radiation, but the treatment does not
usually work well.
"We know that expectations of cure in this type of
therapy is much less than 20 percent," McManus said.
PET Scan Finds Sneaky Tumors
When patients were examined after treatment, many
seemed to have been "cured" according to a CT scan, but
PET scans showed their tumors were still active.
And in some people who seemed to have a tumor
when X-rayed using CT scans, PET showed the mass
was dead tissue. PET scans also showed when cancer
cells invaded a lymph node that appeared normal on a CT
scan because it had not yet begun to grow or change
Patients whose tumors looked active on the PET scans
had four times the risk of dying, and patients whose PET
scans showed the cancer was still progressing had a 45
times greater risk of dying, McManus reported.
"It seems that most of those patients are doomed to
die of their disease," he said.
Dr. Harm van Tinteren of the Comprehensive Cancer
Centre in Amsterdam said PET scans might be used to
help doctors tell which patients might be helped by
surgery or other treatments, and which ones have
hopeless cancers and might be best served by treatment
that eases their pain while they die.
He said up to half of all patients have a disease that,
after surgery, is seen to be more serious than first
His team studied 96 lung cancer patients who received
standard lab tests and 92 patients who got standard tests
plus a PET scan.
"PET more accurately shows the extent and stage of
disease," Van Tinteren said.
McManus said the PET scans also worked for other
cancers such as melanoma, a deadly form of skin cancer,
head and neck cancer and colon cancer.
Predicting the Dangers
A third team of researchers took another approach to
predicting which cancers are the most dangerous.
Dr. Giles Cox of the Leicester Royal Infirmary in
Britain examined tumors taken from 168 patients and
looked for proteins either associated with dangerous
tumors, or known to be involved in tumor growth and
"We looked at the number of blood vessels in each
tumor," Cox said. Tumors grow blood vessels to feed
themselves, a process known as angiogenesis.
They also looked at the levels of enzymes known as
matrix metalloproteinases (MMPs), which are involved in
breaking down and rebuilding tissue so that tumors can
spread, and for a receptor, a kind of cellular doorway,
called epidermal growth factor receptor (EGFR).
"If the tumor had a high number of blood vessels,
MMP-2, MMP-9 and growth factor receptors, then there
was an 84 percent chance of cancer mortality in these
patients," Cox told reporters.
If a patient's tumor had none of these factors, the
chance of death was only 36 percent.
"We can identify those at high risk of recurrence," Cox
said. "The prospect of treatment tailored to the individual
patient and to the individual tumor characteristics, we
believe, is possible."
Drugs are being developed that specifically interfere
with MMPs and with various tumor growth factors.