Ghost Disease Evokes Asbestos Memories
Mesothelioma, a rare cancer, affects a growing number of Canadians, sometimes 20 to 40 years after their exposure
By CAROLYN ABRAHAM
Monday, September 26, 2005 Page A6
MEDICAL REPORTER
When Marilyn Bertrand was six, her big brother returned from his summer job at Thetford Mines in Quebec's Eastern Townships and presented her with a fuzzy, white rock from underground.
Marilyn treated it like a doll and took it with her everywhere, even to bed.
When she was 41 and doctors in Winnipeg wondered how such a young woman could develop mesothelioma -- a rare and deadly cancer of the chest cavity -- Mrs. Bertrand remembered her pet rock and how she'd slept with it. No one at the time realized the full hazards of cuddling with a hunk of asbestos.
Mesothelioma is the cancer known to strike 20 to 40 years after exposure to asbestos, the fibrous mineral once considered the magical fire-retardant in such things as home insulation, break lines and pipe wrap. The disease is now like a ghost, visiting Canadians in growing numbers and bringing back old memories.
For Mrs. Bertrand, who died of the disease in 2002, it was the gift from her brother. For Conservative MP Chuck Strahl, diagnosed in August, it was changing asbestos break pads on the tree-dragging yarder in the 1970s.
The cancer develops in the mesothelial cells that form a wax-paper-thin lining around body parts, such as the pericardium, which holds the heart, and the peritoneum, which houses the stomach. Often it sprouts in the pleura, the tissue layer that covers the lungs and lines the chest cavity, as it has done in the case of Mr. Strahl.
Experts liken mesothelioma to an orphan disease -- poorly understood and with few specialized drugs to treat it because it's rare. In 2001, the most recent year for which numbers are available from the Canadian Cancer Society, 399 Canadians were diagnosed with mesothelioma and 297 people died of it.
The low numbers contribute to mesothelioma's nearly invisible profile. A situation made worse, said Joseph Testa of the Fox Chase Cancer Centre in Philadelphia, because the multisyllabic monster is hard to pronounce. The public often mistakes it for lung cancer. It also tends to hit older men who have worked with asbestos in mining, shipping or construction --
"tough guy" types unlikely to seek an early diagnosis for their pain or organize a walkathon to raise awareness.
Dr. Testa, director of human genetics at Fox Chase and an expert on mesothelioma, said it seems certain that co-factors, other than asbestos exposure, contribute to the development of the disease.
Studies suggest only 5 per cent of asbestos miners, for example, develop mesothelioma. This, Dr. Testa said, suggests that some people are genetically vulnerable to the damage asbestos causes or that a virus might act as a catalyst.
But, he said, with outstanding lawsuits from asbestos exposure victims, not everyone wants to hear that asbestos many not be solely responsible.
In roughly 90 per cent of cases, a prior asbestos exposure is clearly involved in mesothelioma. In fact, Dr. Testa said, a Massachusetts study found no cases on record before the 1950s, when asbestos had already been a fixture in industry for more than 60 years.
It's believed mesothelioma may take years to develop after an exposure because it slowly effects changes to human DNA. One view, Dr. Testa said, is that asbestos directly damages mesothelial cells. Photographs have shown that the needle-like asbestos fibres can literally spear a cell's nucleus.
Another theory is that macrophages, large, patrolling immune cells, try to attack asbestos fibres and scatter free radicals, or oxygen particles, that foul up the genetic machinery of the mesothelial cells.
In both cases, Dr. Testa said, cells lose control of their growth and divide rampantly, increasing the chances further genetic damage will accumulate. Many years later, a tumour forms.
In other cancers, tumours tend to form as lumps, or balls of cancerous cells. But the messy tumours of mesothelioma are barely distinct from the tissue in which they grow, forming, for example, a fibrous shell like a peel around the lungs.
"It's a thick, hard, gritty kind of tumour," said Michael Johnston, a thoracic surgeon at Toronto General and Princess Margaret hospitals. It can leave patients with a crushing feeling in their chests, a shortness of breath and cough, as fluid and tumours build around the lungs and creep further along the lining.
Left untreated, Dr. Testa said, most patients will die within six to eight months of the onset of the disease. Some can make it to two years or more. In very rare cases, patients with a slow-growing mesothelioma can survive even longer.
Mike Bertrand said his wife, Marilyn, was given three months to live after doctors realized in 1994 that her aching back was caused by mesothelioma. But with rounds of chemotherapy and radiation, Mrs. Bertrand lived eight more years.
"She was lucky," Mr. Bertrand said.
Experts agree prognosis has suffered because the disease is usually only discovered in its latter stages when symptoms turn up. But efforts are under way to develop early blood tests to screen those with known asbestos exposures.
Dr. Johnston is running a bus between Toronto and Sarnia, which has one of the country's highest mesothelioma rates, to give former workers exposed at a petrochemical plant low-dose CT scans.
Doctors have roughly three options to treat mesothelioma. If the disease appears to grow slowly and seems contained, they may just drain the excess fluid from the pleural cavity, watch and wait. They may recommend chemotherapy drugs, or if the cancer appears not to have spread, radiation.
In a few cases, if the cancer is not aggressive, and the patient is young and fit, Dr. Johnston said he will recommend a new surgery research trial. It's a gruelling regimen that involves chemotherapy, a full-day operation that can include the removal of an entire lung, the lining of the chest cavity and part of the diaphragm, and a blast of radiation six weeks later.
(The 48-year-old, marathon-running Mr. Strahl is not a surgery candidate because his disease has been found in both lungs.)
Barbara Melosky, a medical oncologist at the BC Cancer Agency, is optimistic, saying people who were exposed to asbestos are becoming more aware of their risks and that drugs designed to treat other cancers are being shown as possible therapies for mesothelioma.
Dr. Melosky said the incidence of the disease is increasing, but case numbers are expected to peak in 2014. By then, research suggests the asbestos exposures of the past will have caught up to most North Americans.
From the Globeandmail
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