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
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
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
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
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
"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
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