Eileen’s Story: Training for the Next Chapter After Breast Cancer

At 34, Eileen Nuñez was in a stable place in her life, with a growing commitment to her physical health, wellness, and fitness. Then, last spring, she felt a lump in her breast. At first, Eileen wondered if it could be related to complications with her breast implants but decided not to ignore it either way. 

The possibility of breast cancer was not entirely unfamiliar to her. Nearly a year before her diagnosis, Eileen tragically lost a close friend to the same disease. As soon as she felt the lump in her breast, she knew she should have it checked by her doctor. 

“That urgency was life-changing,” Eileen says.  

In March 2025, Eileen was diagnosed with stage 2 triple-negative breast cancer (TNBC), an aggressive form of breast cancer that lacks receptors for estrogen, progesterone, and the HER2 protein. Because these receptors and proteins are absent, some of the treatments commonly used for other types of breast cancer are not effective against TNBC. She also learned she was among a growing number of younger women diagnosed with breast cancer under 40. 

“We all think, ‘It’s not going to be me,’ right?” Eileen said. “Until it happens to you.” 

Planning Her Care, Her Future, and an Impromptu Wedding 

At the recommendation of a family member, Eileen connected with Luona Sun, MD, a breast surgeon at Columbia University Irving Medical Center /NewYork-Presbyterian Hospital, who saw her within a matter of days. Following her diagnosis, Eileen found herself making rapid decisions about what she wanted from her care, including deciding to freeze her eggs before undergoing treatments that could lead to infertility. Even then, she found it difficult to think that far ahead knowing that her friend’s experience with cancer had been fatal. 

“That was my only personal experience with cancer,” Eileen said. “In my head, I was already thinking the worst.” 

But Eileen credits her doctors at Columbia for carefully guiding her through the treatment process, taking time to build trust, and treating her with compassion. 

“Their empathy was the most important part for me because I needed people who would treat me like a human being and not just a patient,” she says. 

She began a neoadjuvant chemo-immunotherapy regimen, under the guidance of Julia McGuinness, MD, a breast oncologist at Columbia. This approach combines chemotherapy and immunotherapy before surgery to shrink the tumor and treat cancer cells in the body, while allowing doctors to assess how well the cancer responds before surgery. Surgery would then remove the remaining tumor and allow doctors to determine whether any cancer remains. 

Initially, Eileen’s experience of the treatment went well. Her symptoms were mild, and cold capping helped minimize hair loss. 

Prior to her diagnosis, Eileen and her partner had talked about getting married, with a possible proposal on her birthday that year. As she began chemotherapy, she joked, “You better propose to me before I lose my hair.” 

And he did. Within the first three weeks of getting treatment for her cancer, Eileen planned a wedding, and by mid-June, the couple was married. Her strong support system pushed her through the initial treatments, even as her physical symptoms from treatment got worse. 

"That was very challenging because, on top of not feeling well, you look in the mirror and you don’t recognize yourself.” Eileen explains, “I felt betrayed by my body.” 

Eileen eventually underwent breast surgery to remove her tumor and surrounding tissue with Dr. Sun and breast reconstruction with Jarrod Bogue, MD. About a month later, the doctors found that while the tumor was much smaller, a sign the treatment was working, about 0.1 millimeters of residual cancer remained in her tissue.  

She quickly began oral chemotherapy and immunotherapy to reduce her risk of the cancer returning. Her treatment was successful but led to lasting side effects, including hypothyroidism and mildly reduced heart function which are both being managed safely. 

A New Starting Line 

After finally finishing her remaining cancer treatment, Eileen feels, at once, relieved and nervous.  

“There’s a celebratory feeling knowing that I went through one of the most challenging things in my life and came out on the other side,” Eileen said. “But there’s also a scary part about finishing treatment, because you’re no longer actively doing anything about the cancer.” 

Eileen is now channeling the uncertainty of survivorship into rebuilding trust in her body. “You’re motivated to be the best version of yourself, knowing our time here is limited,” she says. 

That mindset has brought Eileen back to something that once made her feel strong: running. She is training for the New York City Marathon, which she plans to run in November with The Pink Agenda, a breast cancer organization that funds critical cancer research, including at Columbia, and raises awareness of the disease among young professionals. 

“I always tell patients that cancer treatment is a marathon, not a sprint,” McGuinness says of Eileen’s decision to run. “Eileen dug deep into her inner strength to get through treatment, and I can’t wait to see her channel all of that as she joins thousands of runners on the NYC Marathon field.” 

After months of intensive treatment, marathon training has given Eileen a way to reconnect with her body, recognize its strength, and regain a sense of ownership over it. “It’s a good challenge for me, and a full-circle moment to be running for a breast cancer organization I feel connected to.” 

She also wants to use her advocacy to continue sharing what she wishes she had understood sooner about the rise in early-onset breast cancer and believes that seeking care quickly made all the difference in her own treatment. 

“The stage you’re diagnosed at can completely change your life, especially when you’re diagnosed younger. It can be the difference between life and death. And there’s so much more life to live.”