Health: 1)Can a blood test predict if your cancer is coming back? Toronto researchers are betting on it; 2)Scratching that bug bite might feel good at first but science explains why it’s a bad idea

Courtesy Barrie360.com

By Logan Miller, July 8, 2026

For many people in Simcoe County who’ve gone through cancer treatment, the follow-up appointments in Toronto are part of the routine. A new trial out of one of the city’s biggest cancer hospitals could eventually change what happens at those appointments, and how much waiting and worrying comes with them.

Researchers at Princess Margaret Cancer Centre are running a large-scale trial to find out whether a simple blood test can catch tiny traces of cancer left behind after treatment, before they’d ever show up on a CT scan.

What the SHERLOCK trial is testing

Lead investigator Dr. Lillian Siu says smaller studies around the world have already shown that cancer DNA can turn up in the blood in amounts too small for a scan to detect.

Now her team needs proof at scale. They’re enrolling 7,000 patients who have finished radiation, chemotherapy or other cancer treatments, and testing their blood for microscopic amounts of tumour DNA.

The test is sometimes called a liquid biopsy.

If it comes back positive, those patients could be offered additional experimental treatments, like new immunotherapies, aimed at stopping the cancer before it has a chance to return.

If it comes back negative, Siu said it could mean the cancer is genuinely gone, which would let doctors stop further rounds of chemo or radiation and spare patients the side effects of treatment they don’t actually need.

The trial, called SHERLOCK, is also trying to figure out whether the blood test works equally well across different types of cancer.

A decade of research building toward this

Clinicians have been studying liquid biopsies to detect leftover cancer, known as molecular residual disease, for about ten years, Siu said.

After matching blood samples against whether cancer actually came back in patients, she said there’s now a “substantial amount of data to show that people who have positive molecular residual cancer, their cancer has a very high chance of returning.”

Siu is the scientific lead at the hospital’s Peter Gilgan Centre for Early Cancer Detection Research.

Still, she was clear that the science isn’t there yet for everyday use. Blood tests to predict cancer recurrence are “not standard of care” right now, and trials like SHERLOCK still need to run their course.

Researchers plan to follow patients for at least five years.

“You need to have the long-term followup to know whether the test is actually predicting longer-term outcome(s), so just stopping at one year is not going to be sufficient in terms of monitoring,” Siu said.

The fear cancer patients carry

Siu hopes the trial will help ease one of the most common fears among cancer patients: that the disease will come back.

“Most patients, even after curative treatment, whenever they come back to the clinic for a followup, I can see that they have fear in their eyes,” she said.

She said many patients feel a wave of relief when a CT scan comes back clear, only for the anxiety to build again ahead of the next one.

“(They wonder) when am I actually free from having this fear that the cancer will come back?”

An outside researcher’s take

Gillian Vandekerkhove, an assistant professor at the University of British Columbia who studies bladder cancer and liquid biopsies, said much of the existing research in this field has focused narrowly on specific cancer types.

She welcomed SHERLOCK’s broader approach, which spans multiple cancers at once.

“They’re going to provide a wealth of information and biobank samples that researchers can continue to explore,” said Vandekerkhove, who isn’t involved in the study.

“Being a Canadian-led initiative is really great for Canadian researchers.”

She also flagged the trial’s limits.

“I think it’s important to recognize this is an observational study. It’s going to help us understand the technology better and the best-use cases, but there will need to be additional trials. This is not something we’re ready to move into the clinic.”

A patient’s story

Paul Lonergan believes the research has already changed his life.

The 68-year-old Toronto man was diagnosed with throat cancer about three years ago. An avid hockey player, Lonergan said his family doctor initially thought he had a virus, until he started “coughing up blood on the ice.”

He was referred to an ear, nose and throat specialist, then to Princess Margaret Cancer Centre, where he went through radiation and chemotherapy.

Lonergan was also enrolled in a separate clinical trial called MERIDIAN, which looked for residual cancer in the blood of patients treated for head and neck cancers.

“The doctor said, ‘I’ve got good news and a little bit of bad news. The tumour’s gone. There’s fragments of cancer in your blood, which is the bad news, but we have a trial drug that can probably help you,'” he said.

He spent several more months on a new immunotherapy drug as part of the study.

“Sure as heck it worked,” he said.

“I’ve done three six-month checkups and I just finished my third one and they said I’m good.”

Lonergan still has trouble swallowing and relies on smoothies rather than solid food, but he’s back on the ice as he continues to recover.

“I don’t care now about being one of the better players or not. I just go out and have fun and exercise and it’s just good to be out and doing that.”

Funding and next steps

The SHERLOCK study is funded by a $50-million donation from the Peter Gilgan Foundation.

Canadian Press health coverage receives support through a partnership with the Canadian Medical Association. CP is solely responsible for this content.

2)Scratching that bug bite might feel good at first but science explains why it’s a bad idea

Courtesy Barrie360.com and The Associated Press

By Lauran Neergaard, July 5, 2026

You’ve likely heard it since childhood: Don’t scratch that bug bite or rash, you’ll make it worse. But why would something that feels so good be bad?

A lot of things can cause itchiness, sometimes serious diseases. Whatever the cause, doctors have long warned that scratching too much can damage the skin. Now researchers better understand why even a mildly annoying itch could put you on an itch-and-scratch cycle if you give in.

How did they find out? In part by putting tiny “cones of shame” onto mice to uncover what happens on a cellular level when an itch gets scratched — or left alone.

They also gained insight into why a good scratch at least at first brings a sigh of relief. After all, not just people and other mammals scratch, even fish do. The commonality suggests there must be some evolutionary reason and the mouse experiment hints at a little germ protection — but still not a reason to scratch.

Expect a more swollen, itchier spot if you can’t ignore that bug bite

Dr. Daniel Kaplan, a University of Pittsburgh dermatologist whose lab studies immune reactions in skin, was exploring a run-of-the-mill type of itch called allergic contact dermatitis, caused by irritants such as poison ivy or nickel in jewelry.

Kaplan’s research team put a rash-inducing irritant on the ears of mice. Normal mice scratched and inflammatory immune cells rushed to the site, increasing swelling. The rash was much milder in mice bred with defective itch-sensing nerve cells. But was the difference really the scratching?

Normal mice put into collars like those veterinary “cones of shame” so they itched but couldn’t scratch gave the answer: They, too, had much less swelling and fewer inflammatory cells.

Kaplan said that evidence matches people’s everyday experiences that scratching really can make things worse.

Ignore a mosquito bite and the itch is “gone in five or 10 minutes for most people,” he said. “But if you start scratching it, it’s your friend for a week,” getting itchier and more inflamed.

The immune system’s first responders can help — and hurt

To understand what was happening in the skin, Kaplan’s team took a deeper look at mast cells, among the immune system’s first responders. When called into action, they release compounds that can help fight germs or toxins — or, through a compound called histamine, trigger itchy allergic reactions.

Scientists have long known that allergens can activate mast cells. But other signals can summon mast cells, too, including pain. And when we scratch, “we tend to scratch until it starts to hurt,” Kaplan noted.

Pain-sensing nerve cells release a chemical messenger called substance P. In findings published last year, Kaplan’s team reported that substance P can activate mast cells through a different molecular pathway than allergens do — a double whammy that explains why scratching further inflames itchy rashes or bites.

Then why does a little scratching feel good?

If we experience pain like touching a hot stove, we’ll learn not to do that again. Yet relief from a good scratch, in evolutionary terms, is positive feedback. Why?

One long-held theory is that it may help creatures slough off parasites like fleas or mites. But Kaplan also was intrigued by other labs’ findings that mast cells could fend off a common type of skin bacteria called Staphylococcus aureus. So his team infected mice and then repeated the cone-of-shame itch experiment. Sure enough, those that scratched had lower levels of that germ on their ears, maybe because of the extra inflammation or some other mast cell-related compound.

But that’s not enough of an upside to change the health advice.

“Ultimately, scratching is deleterious,” Kaplan stressed. “You should avoid scratching,” he said, although acknowledging that it’s “easier said than done.”

Here’s how to handle a minor itch

What fights an itch depends on its cause and there’s a need for better treatments. For now, antihistamines and certain other drugs for hives can tamp down some itchiness triggered by mast cells. Drug companies are experimenting with other approaches called MRGPRX2 blockers that target the pathway Kaplan’s team linked to scratching. Kaplan hopes better understanding of that pathway eventually could help skin diseases such as chronic eczema.

For the summer itchiness of bug bites, poison ivy and other types of contact dermatitis, dermatologists recommend anti-itch balms such as hydrocortisone cream, calamine lotion or oatmeal baths.

Another trick from Kaplan: Menthol-containing creams can temporarily fool the skin into sensing cold instead of itch, just long enough that “if you don’t scratch, then you break that itch-scratch cycle,” he said. “It’s like a cheat code.”