Tuesday, May 18, 1999 Published at 09:24 GMT 10:24 UK
'New era for cancer treatment'
Research breakthroughs were announced at the meeting
Doctors have hailed a number of experimental breakthroughs that could herald a new era in the fight against cancer.
Although still in the experimental stage, doctors said the new techniques could usher in a new era in the fight against cancer.
"These new therapeutic approaches may eventually emerge as treatments that will either replace traditional therapy or will work in combination with chemotherapy, radiation and surgery now commonly used," said Dr Derek Raghavan of the university of southern California.
The meeting started on Saturday and runs until Tuesday.
Cancer's strength turns against it
Cancer cells' natural resistance to chemotherapy could be used to restore the body's immune system, according to a US National Cancer Institute team.
Chemotherapy consists of regular doses of a powerful cocktail of anti-cancer drugs, and - as well as causing nausea, hair loss and diarrhoea - can reduce the immune system's ability to stave off infections.
The technique combines two technologies - gene therapy and stem cell therapy. The first brings new genes into the body, the second involves young cells and is already used to help rebuild the immune system.
Dr Kenneth Cowan and colleagues said they used gene therapy to help the stem cells stand up better to the ravages of the poisonous drugs used in chemotherapy.
They focused on a gene known as MDR-1, which increases drug resistance.
Dr Cowan said the gene was a kind of pump - in normal cells it pumps out toxins and in cancer cells it pumps out anti-cancer drugs almost as fast as doctors can get them in.
The team's experiment involved 10 breast cancer patients, who - before receiving chemotherapy - had some of their stem cells from bone marrow and blood stored and genetically modified to include MDR-1.
After chemotherapy - which destroyed their bone marrow along with the tumours - the modified cells were returned to the patients.
"We can reconstruct the patients' (immune systems) with these genetically modified cells quite easily," Dr Cowan said.
Nasal spray could tackle cancer
Cancer treatments could be administered via nasal spray in the future, the meeting heard.
Researchers presented evidence that the spray could help defeat Kaposi's sarcoma, the most common AIDS-related cancer, and said the principle could be applied to other cancers.
A team from the Los Angeles school of medicine combined two approaches - getting the immune system to attack cancer cells and starving the tumour by blocking the growth of blood vessels.
The team, led by Dr Parkash Gill, achieved this by using a newly-developed protein called IM862.
It can be absorbed through the nasal membrane because it is so small, and so Cytran - the company that developed it - formulated it in nose drops.
Gill's team gave it to 44 Kaposi's sarcoma patients at two sites in Los Angeles and Boston.
Thirty-six per cent of the patients saw the cancer's characteristic lesions completely or partially disappear.
Trials are being conducted to see if the spray will work on cancers of the uterus and skin.
"I expect this compound will have action in other tumours but unless that has been proven you have to have great caution in making that claim," Dr Gill said.
Chemotherapy success may depend on delivery
The success of treating bowel cancer that has spread to the liver can depend on how chemotherapy medicines are given, a team from the Memorial Sloan-Kettering Cancer Centre in New York said.
About 60% of bowel cancers spread to the liver, and, once this has happened, the chances of survival are greatly reduced.
The usual method of delivering chemotherapy drugs is through a vein.
But, in a study involving 158 patients, Dr Nancy Kemeny's team tested the effectiveness of injecting the drugs directly into the hepatic artery, which supplies blood to the liver.
After surgery the patients were randomly placed on either standard chemotherapy or the new method.
Two years later, 85% of those having drugs injected were still alive compared to 69% on standard treatment.
Dr Kemeny said the long-term picture was uncertain, but projections suggested that after five years 60% of those getting the arterial treatment will still be alive compared to 40% getting standard treatment.
"This is a very elegant study and an important one," said Dr Derek Raghaven of the University of Southern California. "This is progress."
Breast cancer drug 'useful in lung tumours'
A drug that is licensed for use in the fight against breast cancer could also be effective in tackling lung cancer that has spread, researchers said.
Lung cancer is the most common form of cancer, and usually does not respond to treatment once it has spread.
The study was conducted at 23 cancer centres across the US. Patients were given one of two drugs - Taxotere (or docetaxol) and Navelbine (or vinorelbine).
Thirty-two per cent of patients who got Taxotere lived for one year after treatment, compared to Navelbine.
Dr Frank Fossella of the MD Anderson Cancer Centre at the University of Texas said: "In view of the poor survival rate seen in these patients, our trial results provide optimism about the future management of the disease."
A second study involving Taxotere found that, when used in combination with another drug, it could also improve the outlook for patients with prostate cancer.
And another study found that a new drug against diabetes can also kill off cancerous cells.