Whether technological advances and understanding disease at a molecular level would deliver tangible benefits for health care in the next millennium was discussed by leading scientists at a Conference symposium on September 10
The genetic revolution will impact on the whole of the cancer and medical world,”
said Professor Gordon McVie (director general, Cancer Research Campaign).
The virtual completion of the initial draft of the human genome project had
raised the public's awareness and expectations, he said. But how would this
technology impact on health care? Cancer was a good illustration of how progress
in the application of genetic technology might be made, he commented. Many of
the important genes identified were linked to cancer and much of the technology
driving the human genome project had emerged from cancer laboratories. It was
not just cancer specialists who got excited about the human genome project,
but also those working in other fields, including infectious diseases, he said.
In the case of tuberculosis and leprosy, many aspects, such as transmission
and dissemination, appeared to be genetically determined.
In general, technology had dramatically changed the pace of medical advances,
suggested Professor McVie. Scientists now knew enough genes and their products
not to give any excuse for failing to develop better cancer treatments. The
technology was also now available to enable these targets to be seen: chromosomes,
telomeres and stretches of genes could be “sorted” and visualised
and robots were available to identify large numbers of genes and proteins. If
this technology was harnessed by pathology laboratories, it would become routine
for the status of 3,000 to 4,000 genes to be determined from a few cells from
a single patient, he predicted.
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| Advances in genetic research meant that scientists had no excuse for failing to develop better cancer treatments, Professor McVie said |
It was advances in mathematics that were limiting the use of this extraordinary
avalanche of information.
Technological advances also raised other questions such as issues of “cancer
management”, Professor McVie reminded Conference participants. “We
are in a caring profession and must devise strategies for intervention,”
he continued. The concept of “genes” was sometimes difficult to understand
and there was considerable confusion about genetics among patients. For example,
he said, carriers of the breast cancer genes only accounted for seven per cent
of patients with breast cancer. So what constituted a family history when the
risk of breast cancer was one in 10 anyway? Did counselling help — how
did you tell a woman carrying the breast cancer gene that she had a 50 per cent
chance of being affected by the time she was 50 years old, and an overall lifetime
risk of 85 per cent, he questioned. The discovery of genes and their proteins
had spawned a vast amount of information about predisposition and prognostic
factors, but was the information useful unless there was a therapeutic application,
he asked. It was important that the health service addressed the issue of genetic
information and considered how it should be passed on to the patient: the pharmacist
might play an important role here, he suggested.
There was also the issue of prevention, said Professor McVie. For example, mutations
in the p53 gene (see p487) were associated with
tobacco-related lung cancers and could be picked up in the sputum of heavy smokers.
Should those at risk be identified by screening? Screening programmes themselves
would adapt with time, he suggested. For example, in 20 years time, breast cancer
screening would be reserved for those who carried predisposing genes.
Direct benefit
One example of where the application of genetic advances had led to a direct
benefit to cancer treatment was in the discovery of the HER-2 gene and the development
of the drug trastuzumab (Herceptin), said Professor McVie. HER-2 was a cell
signalling receptor that was often found overexpressed in oestrogen-receptor
negative breast cancers, he said. In itself, the presence of HER-2 was correlated
with poor prognosis and was a useful predictor of sensitivity towards several
anticancer drugs. Moreover, an antibody treatment specific for HER-2 (trastuzumab),
had now been shown to add to patient response and survival although the cost
of treatment was high. The HER-2 example, he said, certainly provided a model
demonstrating the importance of genes in disease and the possibility of therapeutic
cures about which previously one could only dream.
But where there was hope for advances in the treatment of cancer, was there
also some “hype” too, questioned Professor McVie. If there was, it
probably lay with gene therapy as so far there had been few results, he suggested.