Woman, 30, Says Oura Ring Detected 1st Sign She Had Stage 4 Cancer — 8 Months Before Doctors Did

Last August, Casey Cattie began waking up in the morning soaked in sweat.

“I wasn’t hot. I was actually cold because I was under a fan,” Cattie, 30, of Philadelphia, tells TODAY.com. “It was completely drenching night sweats.”

She had been wearing an Oura Ring a friend gave her, and since the nightsweats started, it often informed her that she was “showing sings of major illness.” Cattie saw multiple doctors to get to the bottom of the changes in her body, but none could find the cause.

Then, this past spring, Cattie experienced a medical emergency while traveling in Iceland, where doctors told her they suspected she had cancer.

In April, she was diagnosed with Stage 4 Hodgkin lymphoma. Only her Oura Ring had seemed to notice something amiss with her heath.

“I was seeing all these fevers but nothing else,” she says. “I had all these vague symptoms. And I had seen my primary care provider, I had seen a GI doctor, I got a colonoscopy and endoscopy to check for any type of internal bleeding — all of that was negative.”

Night Sweats and Fevers

At the end of last summer, Cattie kept waking with night sweats.

“They were progressively getting worse,” she says. “I wasn’t thinking much of it, which is really sad to say.”

The pediatric nurse downplayed her symptoms “because (in medicine) you see so many crazy things on a daily basis that you could never think would happen to you.”

At the time, she was wearing an Oura Ring and an Apple Watch to track her menstrual cycle and comparing the data. The ring picked up Cattie’s spiking temperatures.

“If your temperature is so high above your normal, they just assume that you’re sick,” she says. “I did ignore it for a few months because I (thought), ‘Maybe it’s just where I am in my cycle.’ I was thinking of every excuse in the book as to why it could possibly not be accurate.”

After a couple of months, Cattie became worried and set up appointments with a variety of doctors to understand why she experienced night sweats and fevers.

“My doctors ran all of the tests,” she says. “My bloodwork was totally normal except I was iron deficient.

She even met with a hematologist oncologist to rule out cancer.

“She said she had very low suspicion that what I was dealing with was a malignancy,” Cattie recalls. “All my bloodwork was pretty much normal.”

The doctor also noted that Cattie didn’t have any palpable lymph nodes, which can be a sign of cancer (though it is often a sign of viral infections, as well).

While Cattie still felt like something was wrong, doctors found no cause for her fevers, so she continued with her life. To celebrate her 30th birthday, she scheduled a trip to Iceland and felt “excited to explore a new country.”

But, “things were off from the get-go,” she recalls. “I was walking around Reykjavik, the capital city of Iceland, with my friend, and I looked at him, and I was like, ‘Gosh, what is the elevation here? I feel like I can’t breathe.’”

Her friend responded that they were “literally at sea level.” Cattie remembers wondering if she had the flu and that was why she had trouble breathing. On the trip, she continued to struggle with walking and gradually felt so bad that she lost her appetite. By the end, Cattie was so weak.

“I couldn’t even make it to the restaurant next door without stopping to catch my breath three or four times,” she says.

Cattie put off seeing a doctor in Iceland because she was concerned about the cost. But the day before leaving, she visited the emergency room because she worried she wouldn’t be able to fly home because of her labored breathing. Doctors diagnosed her with a “massive pleural effusion,” which occurs when fluid pools around the lungs, making it difficult to breathe.

“I had over a gallon of fluid in my chest,” Cattie says. “I was drowning internally for the week leading up to my diagnosis.”

In the emergency room, doctors drained the fluid from her chest so she could fly home. They ordered CT scans, as well, and told Cattie “they thought it was cancer,” because they detected enlarged lymph nodes. They recommended she undergo a lymph node biopsy and PET scan for a definitive diagnosis.

A few days after she returned home, breathing became difficult again because her chest had filled with fluid again. She visited a local emergency room and doctors admitted her.

“They drained me with a chest tube,” Cattie says. “I had a PET scan two days later that lit up like a Christmas tree. They did a lymph node biopsy three days after that.”

The tests led to a Stage 4 Hodgkin lymphoma diagnosis, and she underwent her first round of chemotherapy while still in the hospital. After two and a half weeks, she returned home.

Doctors said her lymphoma impacted the lymph nodes deep in her chest, causing it to fill with fluid.

“They were so large,” she says. “It was causing irritation within my chest cavity, and that was causing my body to secrete more pleural fluid and continue to re-accumulate fluid in my chest.”

In total, Cattie will undergo 12 rounds of chemotherapy and immunotherapy every two weeks. As of early August 2025, she’s more than halfway through treatment.

“Every round has been different,” she says. “I just don’t really have much of an appetite.”

She also experienced some nerve damage and feels “chronically dehydrated.”

She still wears the Oura Ring.

“It tells me a few days after treatment that I am showing mild signs of illness, which is really interesting to me (and) makes sense because that’s when I feel at my worst,” she says.

Hodgkin Lymphoma

A type of cancer that originates in the white blood cells, Hodgkin lymphoma often grows in lymph nodes, the American Cancer Society says. It can impact the lymph nodes in the chest, abdomen and pelvis, though it also can occur in the spleen, bone marrow, thymus, gastrointestinal tract or adenoids and tonsils.

Fever and night sweats are two of the common symptoms, according to Mayo Clinic.

The American Cancer Society says that almost 9,000 people will be diagnosed with Hodgkin lymphoma in 2025. It occurs commonly young adults though it can impact children and older adults. Treatment includes chemotherapy, immunotherapy, radiation or targeted therapy.

Wearables Detecting Illness

Wearable devices, such as smartwatches and rings, are good at detecting heartbeat and heart rate variability, but for body temperature, “it depends on the device,” Michael Snyder, Ph.D., head of Stanford Center for Genomics and Personalized Medicine tells TODAY.com.

That said, wearables can accurately detect a shift in a person’s baseline metrics, “so even if the temperature isn’t perfectly accurate, you can pick up the shift just fine,” adds Snyder, who studies how wearables can be used to find illnesses before symptoms begin.

Synder and his team have conducted research showing that wearables know when people have respiratory viral infections, such as COVID-19, because the “heart rate jumps up,” he says. They can even detect COVID-19 before symptoms start, his research has found.

And anecdotal reports indicate smartwatches and rings can also notice atrial fibrillation, as the condition causes an irregular heartbeat.

While wearables can accurately track heart rate, they can’t always identify the cause of a change or increase — and there can be many, from ongoing stress to running a marathon.

“The bottom line is what it’s telling you is that something’s off. It doesn’t always tell you what it is,” Synder says. “Many times, you can contextualize it. … If you ran a marathon and your heart rate’s up for a few days, that’s because you ran a marathon.”

If your wearable tells you about an abnormal shift in your body, he recommends talking to a doctor.

“If it continues, you should get it check out. It is very similar to your car’s check engine light,” he says. “If it just blinks, you’d probably ignore it. But if it stayed on for a while, you’d probably get your car checked.”

‘Freaking Amazing’

As a pediatric nurse, Cattie works in the hospital with children. She’s taken a leave of absence because chemotherapy has wiped out her immune system and she’s worried about contracting an illness. Plus, 12-hour shifts while navigating chemotherapy seemed difficult.

Recently, she underwent scans and is pleased with how well treatment is working.

“My scans were clear, which is freaking amazing considering I had tumors all over my lungs, all over my esophagus. I had them on my spleen,” she says.

As Cattie, who is also a musician, reflects on her experience, it still seems unbelievable.

“When I think about everything that I went through in the month of April, I actually can’t believe that that happened to me,” she says. “Being told that you have cancer in a foreign country alone is a type of trauma that I wouldn’t wish on anybody.”

Cattie hopes that people learn the importance of advocating for their health from hearing her story.

“I went eight months with doctors who missed my diagnosis — doctors with 40 years’ experience treating lymphoma and specializing in the kind of cancer I have. I trusted them,” she says.

“I don’t want to throw anyone under the bus here. Basically, if you have a gut feeling something is wrong, you need to trust that gut feeling.”

CORRECTION (Aug. 6, 2025 8:50 P.M.): An earlier version misstated that Cattie had non-Hodgkin lymphoma. She has Hodgkin lymphoma.

This article was originally published on TODAY.com