No silver bullet in dealing with asbestos-related cancer

The Vancouver Sun   |   Owen Munro   |   Published on: December 28, 2016

New methods are giving doctors a better handle on diagnosing and treating asbestos-related cancers, but no cures are on the horizon.

“I think it would be overly optimistic to say it’s going to be cured. I mean we can always dream,” said oncologist Dr. Christopher Lee, an expert on mesothelioma.

Paul Demers, a senior scientist in prevention at the Occupational Cancer Research Centre in Toronto, said one of the difficulties in diagnosing mesothelioma is the long latency period — the period between exposure and the development of symptoms — which can sometimes be up to 40 years.

When asbestos fibres are inhaled or ingested, they become trapped in the pleural lining of the lungs. Over time, thousands of tiny fibres cause scarring in the tissue.

New equipment like the CyTOF instrument allows doctors to detect asbestos earlier and with more precision, which could facilitate more effective treatments for asbestos victims.

The machine offers disease sufferers a less invasive surgery, because of the precision with which it can find asbestos fibres in the lungs. The machine can analyze individual cells and increase the likelihood of a more effective treatment.

But there will be a wait before any concrete progress is made in curing cancers related to asbestos exposure.

“In terms of treatment, we may have some small improvements in slowing down the cancers, but there are no major breakthroughs [in curing it],” said Dr. Stephen Lam, an oncologist at the B.C. Cancer Research Centre.

Another potential treatment could be ready for clinical use in the next few years. Dr. Lee is researching whether cancer cells can be controlled by a combination of chemotherapy and immunotherapy instead of simply treating a patient with conventional chemotherapy.

The study is going through review and is in a Phase 2 trial, where Lee will look to see whether the immunotherapy is effective against a specific cancer such as mesothelioma. The study is being run in multiple cancer centres across Canada, as well as in Italy, but it’s expected to take two years before results are known.

One of the newer techniques aimed at treating mesothelioma is SMART: Surgery for Mesothelioma After Radiation Treatment. It’s a concept championed by radiation oncologist Dr. John Cho and thoracic surgeon Dr. Marc de Perrot at Princess Margaret Cancer Centre in Toronto.

The doctors claim to have doubled survival times in mesothelioma patients. It’s a twist on a general cancer operation in which parts of the affected organ — in this case, the lungs — are removed and radiation kills any lingering cancer cells. The SMART technique uses radiation before surgery in hopes there are no lingering cells after surgery, effectively killing the cancer.

However, Lee believes the main difficulty with this type of surgery is that asbestos fibres often grow in the lining of the lungs.

“It’s not growing as a grounded tumour. It’s growing as a thickening of the lining itself,” Lee said. “It’s growing around the curved surface of the chest, internally around the lung and inside the chest wall. So where do you cut … to ensure you get a normal cuff of tissue?”

Radical surgery isn’t a necessarily modern concept; the 1970s were a time of extremely dangerous surgeries and high mortality rates from them. Lee describes a particularly high-risk surgery called extrapleural pneumonectomy.

Surgeons would open the side of the chest, remove the cancerous lung and the lining around the chest and heart. The surgery was typically given to those in the early stages of mesothelioma so the cancer didn’t spread to the lymph nodes.

While the gap between medical knowledge of asbestos-related diseases and applying that knowledge to treat patients has closed significantly over the past decade, the diagnosis for most is still a grim one. More than 500 people in Canada are diagnosed with mesothelioma every year, and Dr. Lee says we might not see any groundbreaking advancements until 2020.

Tsunami of asbestos-related deaths has yet to reach Canadian shores

WorkSafeBC has been paying out claims to victims of asbestos exposure for decades, and there’s no end in sight.

Deaths from mesothelioma, a cancer caused only by exposure to asbestos, haven’t yet reached their peak in Canada, said Demers. Even when the peak number of confirmed cases is reached, he cautions, it may not decline for another five to 10 years.

“Our best way to monitor the impact of asbestos has been to look at the number of cases of mesothelioma,” Demers said. “Mesothelioma is a cancer that we capture through our tumour registries, and capture it accurately, and can tell how many new cases there are each year.”

Canada had 580 new cases in 2013, with 75 in B.C., according to StatsCan. From 2006 to 2015, 584 deaths in B.C. were related to asbestos exposure, according to WorkSafeBC.

WorkSafeBC is among the country’s leaders in compensating people for mesothelioma, Demers said, but he also believes improvements could be made — including bringing more awareness to the issue of lung cancer from asbestos exposure.

It’s estimated that for every one case of mesothelioma there are up to four cases of lung cancer, but doctors often misattribute lung cancer to cigarette smoking.

“Exposure to asbestos increases the chance of lung cancer in both smokers and non-smokers,” Demers said. “But the baseline risk in smokers is much higher.

“Most of those cases are going to be among smokers and it’s easy to kind of put all the blame on the smoking and really not recognize many of those cases wouldn’t have happened if there was no (asbestos) exposure.”

Many work-related cases of mesothelioma never result in WorkSafeBC compensation for the victims, for a number of reasons: the victims don’t file for it, or they aren’t aware they were exposed at work, or they can’t provide proof that they were. A University of B.C. study found that fewer than half of mesothelioma cases on the B.C. Cancer Agency’s tumour registry between 1970 and 2005 received compensation.

The use of asbestos in almost all facets of construction in Canada until recently means that many buildings and ships likely still have some form of asbestos.

Owen Munro is a graduate of Langara College’s journalism program and recipient of the 2016 Jeani Read-Michael Mercer Scholarship.