UCalgary scientists want your toenail clippings for a study related to lung cancer

At 47 years of age, Emi Bossio, was feeling good about where she was at. She had a successful law practise, two growing children and good health. Then she developed a nagging cough. The diagnosis to come would take her breath away. 

“I never smoked, never. I ate nutritiously and stayed fit. I thought to myself, I can’t have lung cancer,” says Bossio. “It was super shocking. A cataclysmic moment. There are no words to describe it.”

Bossio had to give up her law practice to focus on treatment and healing. As part of that journey, she’s taken on a new role as an advocate to increase awareness about lung cancer. She still has no idea what caused her lung cancer. 

Trying to answer that question is how Bossio became interested in the research Dr. Aaron Goodarzi, PhD, is doing at the University of Calgary. 

Goodarzi leads an interdisciplinary team looking at environmental causes of lung cancer, like radon. The naturally occurring, odorless, colourless but radioactive gas is the second leading cause of lung cancer after tobacco smoking. 

Despite that, rules governing lung cancer screening programs can’t yet include radon exposure as one of the risk criteria. The reason being few people can reliably report their radon exposure across decades like they can report the number of years they’ve smoked tobacco. 

Goodarzi may have a solution. He’s currently recruiting for a study that may provide critical data to estimate a person’s lung-cancer risk on the added basis of long-term radon exposure. To do this he needs Canadians’ toenail clippings. 

Toenails contain a living history of some of the toxins you are exposed to

“We’ve learned that our toenails hold long-term information about our exposure to radioactive toxicants in our environment such as radon gas. They are one of our body’s archives of past exposure,” says Goodarzi, professor at the Cumming School of Medicine and a principal investigator on the study. 

“After you inhale radon, it quite quickly transforms into a specific type of radioactive lead. Your body treats radioactive lead from radon like it does all lead and stores it in slow-shedding tissues such as the skin, hair and nails.”

In a proof-of-concept (pilot) study published in Environment International, Goodarzi and co-principal investigator Dr. Michael Wieser, PhD, showed that measuring radioactive lead in toenails is a promising way to estimate a person’s long-term radon exposure.

“We believe we’ve discovered a reliable, quantitative way to measure long-term radon exposure at an individual level,” says Wieser, a physics professor in the Faculty of Science. 

“We used a combination of personalized radiation dose epidemiology and isotope dilution mass spectrometry to evaluate ultrasensitive measurements of the radon decay product. 

"We tested for lead isotopes in toenail cuttings and proved they can serve as a quantitative method to reveal lifetime radon exposure at an individual level.”

Participants in the Canadian Cancer Society-funded pilot project were recruited from the many thousands of people enrolled in the Evict Radon National Study. With new funding from the Canadian Cancer Society, there is a much larger validation trial underway now. 

Researchers are hoping to recruit up to 10,000 people from all over Canada. Participants will need to test their homes for radon and collect and send in their toenail clippings for analysis by the research team. 

Specialized lab needed to process toenails 

The toenails are being analyzed in a specially designed lab within the Environmental Cancer Research Hub at the Arnie Charbonneau Cancer Institute. 

The lab is metal free. The counters and shelves are all made of plastic and the walls have been painted with a unique coating to prevent contamination of the samples. 

Researchers within the lab must wear plastic shoes and plastic lab coats. Strict protocols are in place on what materials can enter the lab and how they can be used. 

The first step in processing the toenails is to separate the lead isotopes from the rest of the atoms in the sample. This is done using a high-powered microwave to break down the sample followed by ion chromatography techniques. 

The samples are then measured on the newest generation of multi-collector mass spectrometer, a specialized instrument that can count the individual atoms of a specific isotope.

“It was a challenging task to develop the methodology to measure an ultratrace amount (femtogram quantities) of the isotope,” says Dr. Kerri A. Miller, PhD, first co-author of the pilot study. 

“In this case we were measuring ²¹⁰Pb. For these samples we were battling both detection limits and spectral interferences on the preparation and instrumentation side of things. But we found a way to do it reliably and now we can use this technology to improve the way we assess personalized radon exposure.”

Researchers say toenail clippings are a useful tissue for analysis because they are, at least compared to fingernails or hair, more protected from a lot of the chemical contaminants that people routinely come into contact with. Chemicals such as dyes, manicure products, cleaning products, and household or occupational chemicals may complicate the analysis. 

Along with the toenail clippings, researchers also collected lifestyle data from the participants; things like the amount of time someone spends in their home, at work, in another person’s residence, or in a vehicle or outside.

“In greater or lesser amounts, radon is everywhere - in all the buildings in which we live, work and play, and we see this in our data,” says Dr. Dustin D. Pearson, PhD, first co-author of the pilot study. 

“The amount of time spent at home, at work, at another’s residence or outside turned out to be essential in understanding our data as it defines a person’s dose of radiation from radon. With this information we were able to decipher what our toenails were saying about our radon history and develop, for the first time, a reliable lifetime radon measurement that looked back in time, as well as across environments.” 

These data, together with the results from radon home tests, created one of the most wholistic radon exposure studies yet, working back from human behaviour and how that altered the atomic markers of exposure.

Science as the basis for potential policy change 

“If this validation trial works, it could transform the future landscape of cancer prevention in Canada. The data will form the evidence that could lead to the inclusion of more patients, whose lung cancer is not caused by tobacco smoke, in potentially life-saving early screening and diagnosis,” says Goodarzi.  

In the pilot study, the researchers noted that a major unmet health-care need is that two in five people who develop lung cancer in Canada today do not meet current screening inclusion criteria, with half of those never having smoked tobacco at all, and another half smoking too little, or too long ago, for tobacco alone to be considered causative.

Tim Monds is one of those people. A non-smoker who in 2016, at the age of 57, was diagnosed with stage one non-small cell lung cancer (NSCLC). Within two years, the cancer progressed to stage four. 

“Lung cancer patients, like me, are living longer. That’s great, but we need to identify cancer-risk sooner. We know early detection and screening programs are effective in lowering mortality rates,” says Monds. 

“People need to understand anyone with lungs can get lung cancer,” says Bossio. “I applaud the research the Goodarzi lab is undertaking.”

Learn more about the new toenail study and criteria to participate here.