Breast Cancer is Shrinking For ‘Bachelorette’ Star, 34, ‘You Can’t Even See It On a Scan’

Thurston’s path to this moment has been anything but straightforward. She was initially diagnosed with stage 3 triple-positive breast cancer, a rare and aggressive subtype of luminal breast cancer.

According to Cancer Cell International, “Triple-positive breast cancer (TPBC), a unique subtype of luminal breast cancer, is characterized by concurrent positivity for estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2).”

This subtype accounts for only 5–10% of all breast cancer cases and typically requires a multi-pronged approach—combining chemotherapy, HER2-targeted therapy, and hormone (endocrine) therapy.

WATCH: Second Opinions on Your Cancer Diagnosis or Treatment: Do You Need One?

But after seeking a second opinion, Thurston learned her diagnosis had changed: she was now facing stage 4 HER2-negative breast cancer. That revelation dramatically altered her treatment plan.

“I was very close to being treated potentially with the wrong medication,” she said.

HER2, short for Human Epidermal Growth Factor Receptor 2, is a protein that can accelerate the growth of breast cancer cells. Its presence—or absence—plays a critical role in determining treatment options.

As Dr. Elizabeth Comen, a medical oncologist, explained to SurvivorNet, “These receptors, I like to imagine them like little hands on the outside of the cell… they can grab hold of what we call ligands… hormones that may be circulating in the bloodstream… and used as a fertilizer, as growth support for the cells.”

Traditionally, HER2 status has been classified as either positive or negative, though about half of patients fall into a gray area between the two. HER2-positive cancers, which make up roughly 15–20% of breast tumors, tend to grow and spread more rapidly—but they’re also more likely to respond to targeted drugs like Enhertu.

Thurston’s updated diagnosis meant pivoting to a more precise treatment strategy. While specific details of her regimen haven’t been disclosed, she confirmed she’s undergoing targeted therapy—a form of precision medicine that, according to the National Cancer Institute, “targets proteins that control how cancer cells grow, divide, and spread.”

Her story is a powerful reminder of the importance of second opinions, accurate diagnosis, and personalized treatment.

Targeted Therapy Brings Potential Side Effects

Although targeted therapy can be quite helpful, it comes with side effects. If you experience any abnormal symptoms, contacting your doctor should become a top priority. Patients who are taking more than one immunotherapy drug, referred to as combination therapy, are at an increased risk of experiencing side effects.

WATCH: Understanding HER2-Negative And Ultra-Low: What It Means For Your Breast Cancer Treatment Options

Common immunotherapy side effects include:

• Nausea/vomiting
• Decreased white blood cell count
• Anemia: decreased hemoglobin
• Fatigue
• Constipation
• Decreased appetite

There were several other potential side effects listed as well. Before beginning any new treatment, it’s important to discuss potential side effects with your doctor or medical team. To help manage the side effects, the healthcare provider may:

• Reduce the dose
• Delay the dose
• Or even stop the medication.

Katie’s Ongoing Treatment

Thurston previously shared that her treatment regimen includes three key medications:

• Kisqali (ribociclib): Approved by the FDA in 2017, this targeted therapy is used in combination with endocrine therapy to treat HR+/HER2- breast cancer. It works by slowing the progression of cancer, offering a more tolerable alternative to traditional chemotherapy.
• Lupron (leuprolide): A hormone therapy injection that lowers estrogen levels in the body, helping to prevent the cancer from growing.
• Letrozole: An aromatase inhibitor that reduces the body’s estrogen production, commonly used in postmenopausal women with hormone-sensitive breast cancer.

Treatment Options for Advanced Breast Cancer

Metastatic breast cancer (also called stage 4) means cancer cells have spread from the breast to other parts of the body, which may include the bones, liver, lungs, brain, and beyond.

Breast cancer spreads through the bloodstream or lymphatic system. The blood carries cancer cells to different body parts, where they grow as new tumors.

As the cancer spreads to other body parts, patients may experience additional symptoms depending on where the cancer has spread. Examples include:

• Bones: Severe bone pain or fractures
• Lungs: Difficulty breathing, chest pain, new cough
• Liver: Yellowing of the skin (jaundice), abdominal pain, nausea, and/or vomiting
• Brain: Headaches, memory loss, changes in vision, seizures

WATCH: Treatment options for metastatic breast cancer.

Although stage 4 breast cancer is not curable, several treatment options exist that can extend the life of patients. Treatment options depend on the stage, type of primary breast cancer, and whether hormone receptors are positive.

Treatment can include a combination of:

• Chemotherapy: Oral or IV medications that are toxic to tumor cells
• Hormonal therapies: Drugs that lower estrogen levels or block estrogen receptors from allowing the cancer cells to grow
• Targeted therapies: Drugs that target your tumor’s specific gene mutations
• Immunotherapy: Medications that stimulate your immune system to recognize and attack cancer cells
• Radiation: The use of high-energy rays to kill tumor cells and shrink tumors
• Surgery: To remove a cancerous tumor or lymph nodes (uncommon with stage IV; more common in stages I, II, and III)
• Clinical trials: Studies of new medications, treatments, and other therapies offer hope for better outcomes.

Questions to Ask Your Doctor

If you’re facing the option of having a mastectomy, here are some questions to consider asking your doctor:

• What can I do to prepare for a double mastectomy?
• What happens before and after the procedure?
• For reconstruction, what are the benefits of using implants over my own tissue and vice versa?
• What should I know about implants?
• What will recovery look like after the procedure?

Learn more about SurvivorNet's rigorous medical review process.

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