Shara Garrett was all of 28 when she learned she had a disease usually associated with people at least twice that age: colon cancer.

No one was more surprised than Garrett, whose family history suggested no special risk of the condition. She'd been experiencing pain and bloating, but that came on the heels of abnormal, frequent menstrual cycles. An ovarian disorder seemed more likely.

"I was in disbelief when I found out about the diagnosis," says Garrett, a Houston Methodist patient from Baytown. "So many things ran through my mind at once — I just wasn't expecting colon cancer to be the diagnosis after examining everything."

But cases like Garrett's are no longer so unusual. Colorectal (colon and rectal) cancer is still primarily an older person's disease — the average age of diagnosis is 67 — but the demographics are rapidly shifting. The numbers are decreasing in seniors and increasing in people under 50. Since the mid-1990s, the latter's cases have increased by about 50%.

Even if the numbers are still relatively small, the highest percentage spike is occurring among those in their 20s and 30s, according to a recent study. What's more, colorectal cancers in such adults tend to be more aggressive and not caught until later, more-difficult-to-treat stages.

"Colorectal cancer can strike you at any age," says Dr. Monisha Singh, an oncologist with the Houston Methodist Neal Cancer Center and Garrett's doctor. "More people need to be aware of that."

Garrett's cancer journey dates to December 2021 when she went to the ER with severe stomach pain and bloating. A full-body CT scan and several ultrasounds revealed the symptoms' source: a mass involving her right ovary and a portion of her intestines.

Garrett had emergency surgery, where doctors removed the cancer, the right ovary and the sigmoid colon, the S-shared section of the colon that connects to the rectum.

The final pathology report from the surgery provided the definitive diagnosis: locally advanced stage 4 colorectal cancer. It had started in the colon and grown into and replaced her ovary.

What followed was a lot of chemotherapy.

Scans showed no measurable cancer after the visible tumor's removal, but standard treatment calls for chemotherapy to lower the risk that cancer will regrow. Sadly, it didn't have the desired effect — after three rounds of the treatment, Garrett's cancer markers were increasing.

The CT scan showed Garrett had grown a football-sized mass in her pelvis. Testing found it was cancerous.

Garrett's doctors doubled down. Every two weeks over the next several months, they gave her intravenous infusions of three chemotherapies, an 11-round regimen that caused extreme nausea and made eating and drinking difficult.

But it worked. Garrett's tumor stopped spreading, even shrank, and her tumor markers went down.

The final step was a procedure only available at about 15 U.S. medical centers. During the procedure, surgeons remove any tumors and affected organs and then doctors use specialized catheters to treat any remaining cancer cells in the abdominal cavity with an infusion of chemotherapy heated to approximately 120 F.

The procedure treats certain abdominal cancers, but isn't considered standard treatment for colorectal cancer.

"Aggressive chemotherapy was controlling the disease, but it would not be curative on its own," Dr. Singh says. "So we felt we should be more aggressive."

That meant removing all those organs impacted by the tumor — appendix, left ovary, uterus, gallbladder and part of her colon. Garrett was floored by the scope of the plan. But in the end she felt assured by doctors' counsel that it was necessary because her tumor was so aggressive.

The surgery, performed last December by Dr. Amanda Arrington, a surgical oncologist with Houston Methodist, lasted about 10 hours. By all the usual measures, it appears to have been a great success.

"Having the surgery was probably the best choice," says Garrett, whose recovery lasted about three months, including two weeks at the hospital. "I have gotten better. I've had tests done, blood work done and everything's coming back good."

Garrett can now do more of the things she loves: spend time with family and friends and enjoy her life — and food. For much of her treatment, Garrett had difficulty eating and drinking. Now she's able to go out to eat at restaurants with friends and enjoy the experience.

Garrett is not out of the woods yet. Even though a post-surgery test to detect cancer DNA in the blood came back negative — cancer has an 80% chance of returning if the test is positive — she is receiving low-dose chemotherapy because Dr. Singh feels "there could always be a few residual cells there."

The expectation is to stop such maintenance therapy as Garrett continues to have no evidence of disease with normal scans and negative cancer DNA blood tests.

(Related: Why Even Young Adults Should Care About Colorectal Cancer Screenings)

After her surgery, Garrett turned 30 years old, 15 years younger than the age at which the U.S. Preventive Services Task Force recommends periodic colon cancer screening begin.

"Obviously I'm a prime example of 'it could happen to anybody at any age,'" Garrett says.

The guidelines do recommend screening in younger adults in some circumstances: a family history of colorectal cancer or polyps; an inflammatory bowel disease such as Crohn's disease or ulcerative colitis; or certain genetic syndromes. In addition, a colonoscopy, the best test to detect colorectal cancer, can be ordered if someone experiences blood in the stool; frequent, unexplained diarrhea or constipation; chronic stomach pain or gas; weakness; or unintended weight loss.

Garrett's takeaway from her ordeal: Advocate for yourself and any symptoms you may have. Conquer your fear of getting checked out because it's better than remaining in the dark.

"Don't keep guessing and wondering," says Garrett. "Go see a doctor, whether you're 30, 20, 18. When you do go, the doctor may say, 'You're not at the cancer screening age yet.' But you know your body, you know when it's not doing what's normal. Regardless of what the doctor says, it's still your right to say, 'Well, I want to do it anyway.'"