During her first half-marathon, Karina Ureña battled persistent nausea that threatened to derail her run.

Ureña, a dedicated and health-conscious 30-year-old, had been rigorously preparing for the February 2025 event for several months.

In the six months leading up to the race, what she initially dismissed as menstrual cramps evolved into frequent vomiting and intense pain. Cancer was the furthest thing from her mind.

The California native stated, “I thought it was just my period. I was eating well, running every day, and felt at my peak health. Cancer didn’t even cross my mind.”

Starting in August of the previous year, her anticipated vacations to destinations like Key West, Florida, Maui, Hawaii, and Mexico were overshadowed by her illness.

‘I’d be driving and suddenly have to pull over to vomit,’ she said. ‘I told myself it was stress, jet lag, or food, but deep down, something didn’t feel right.’

By October 2024, Ureña said she was constantly fatigued and losing weight rapidly, but was continuing to train for the 13-mile San Francisco Half. 

‘I threw up five times during that race,’ she said. ‘But I finished it. I didn’t want to admit to myself that something serious might be wrong.’

Karina Ureña, 30, was diagnosed with stage 4 colon cancer after throwing up five times during her first-ever half-marathon. She is pictured above

Afterward, she went to the ER, but doctors dismissed her symptoms as a stomach bug or hormonal issue and prescribed her anti-nausea medication that only masked the pain.

It wasn’t until February, and after several other visits, that her primary care doctor finally ordered the scan that revealed stage four colon cancer.

Describing the moment, Ureña said the results came through on her patient app before her doctor had even returned to the room.

She said: ‘I’ll never forget reading the words, a 3.6-inch (9.2-centimeter) mass on my ovary, cancer that had spread to my liver and lungs. My heart dropped.’

‘My mom was sitting next to me, smiling, making small talk. When I told her, she broke down crying. That moment is something I’ll never forget.’

Doctors told her that the cancerous cells had originated in her colon, but had then spread to her ovaries, liver and lungs before they were detected. The mass on her ovary was about the size of a small orange.

Ureña is one of an ever-growing number of young, otherwise healthy Americans who are being diagnosed with colon cancer before their 50th birthday.

Ureña was told by doctors that her cancer had spread to her ovaries, lungs and liver. She has had surgery to remove the cancer from her ovaries and 11 rounds of chemotherapy

About 2,600 people under 50 years old are now diagnosed with colon cancer in the US every year, estimates suggest. Cases are expected to double between 2010 and 2030 after having risen two percent a year since the early 2000s.

Doctors are stumped as to the cause, but have blamed everything from rising rates of obesity and a sedentary lifestyle to a disrupted microbiome and toxins in the environment.

But those reasons fail to explain why healthy, fit people like Ureña are being struck by the disease.

After her diagnosis, doctors initially offered Ureña a full hysterectomy, or an operation to remove her uterus and ovaries, which they said would prevent the cancer from spreading any further.

But for Ureña, who hopes to become a mother one day, the suggestion was crushing. She said: ‘The thought of losing that part of me was unbearable.’

After talking to her doctors, in March 2025, Ureña went for a smaller surgery to remove the largest tumor on her right ovary.

During the procedure, doctors also removed tissue from her colon, which led to Ureña also being fitted with a colostomy bag, or a pouch worn on the outside of the body that is used to collect stool from the intestine.

Ureña worked in the insurance industry before her diagnosis and lived a busy life traveling to meet friends across the country

‘It was such a shock at first,’ Ureña said, explaining the moment she found she had a colostomy bag. ‘I remember waking up and feeling completely different.’

‘Learning how to live with a colostomy bag has been a huge adjustment, both physically and emotionally, but I’m slowly getting used to it. It’s become part of my fight, a reminder that I’m still here and still healing,’ she added. 

After the surgery, Ureña was referred for 11 rounds of chemotherapy. 

Her treatment is currently ongoing, and Ureña said she was still seeking advice from doctors about whether there might be a way to save her uterus.

The American Cancer Society says only about one in 10 patients diagnosed with distant colon cancer, or colon cancer that has spread to the liver, lungs and other parts of the body, survive for five years after their diagnosis.

Her family has also had experience with cancer before, after her father was diagnosed with stage 3b colon cancer in 2015, and then quickly beat the disease. 

She said: ‘Watching my dad go through it was heartbreaking. I never really got over it emotionally. But seeing him alive and healthy today gives me hope that I’ll get there too.’

She added: ‘It’s strange. My dad beat stage 3 colon cancer 10 years ago, and now I’m fighting stage 4. 

Ureña is pictured above during her cancer treatment. She remains hopeful that she will beat the cancer

‘We did all the genetic testing, and it’s not hereditary. That’s the part that really messes with my head. But it also reminds me that anyone, at any age, can get this.’

Ureña is sharing details about her battle against the cancer on her TikTok page, where she posts treatment updates, health reflections and moments of success.

One of her biggest supporters while she battles the cancer has been her mother, Ureña said, who has accompanied her to every chemotherapy session.

‘My mom has been my rock,’ Ureña said. ‘She always knows how to comfort me when I’m sick. She takes me out into nature, even if it’s just to sit and listen to the birds. Those moments remind me I’m still me.’

Though chemotherapy has taken its toll, fatigue, nausea, and living with a colostomy bag among the hardest adjustments, Ureña said she still finds beauty in small, ordinary things.

‘This diagnosis has taught me to slow down and appreciate the little things,’ she said.

‘I love sitting outside with my cup of tea, listening to the birds, feeling the fresh air. I used to be go, go, go, now I let myself just breathe.’

As for the future, Ureña remains grounded yet hopeful.

‘I’ve learned what truly matters, my health, my family, my close friends,’ she said.

‘I’ve put my life on pause, but that doesn’t mean I’ve stopped living. I still laugh, I still dream, and I still believe in healing.’

Her message to others her age is simple: ‘Listen to your body. Don’t ignore persistent pain or changes that don’t feel normal. Prevention can save your life. 

‘If I’d gone to the doctor sooner, maybe things would be different. But all I can do now is fight, and I’m not giving up.’