Sebastián (Sebas) Casaus Natale: Charting a Clearer Path for Ultra-rare Cancers

Sebastián (Sebas) Casaus Natale was a typical energetic toddler growing up in Albuquerque, New Mexico, with his parents, Michael Casaus and Naomi Natale, and his older brother, Santiago. In August 2021, just after his 2nd birthday, Michael and Naomi noticed a lump in the palm of Sebas’ hand. At first, they thought it was something simple like a bug bite or an injury from riding his bike or playing. But when it didn’t go away after several days, they sought medical attention.

Four long weeks after Sebas’ care team identified it as a “mass” and surgery, the family received the diagnosis: myoepithelial carcinoma (MEC), an ultra-rare cancer. Further scans revealed 11 nodules in both of his lungs. “That was a signal that the cancer was metastatic, stage IV,” Michael recalled.

What followed was not just a devastating cancer diagnosis, but an absence of answers. Sebas’s care team had never treated a patient with MEC. There were no standard protocols, no widely accepted therapies, and almost no research to guide decisions. “We really felt like we were stepping into darkness,” Michael said.

Naomi and Michael found that they had to make treatment decisions, often without clear evidence to guide them. Doctors recommended chemotherapy based on a small study involving just seven pediatric patients, none of whom had metastatic disease. Radiation therapy carried the risk that Sebas’s hand might stop growing, so doctors recommended amputation instead. “These decisions are ultimately made by us, the parents,” Michael said. “When there’s such limited information, it felt like throwing a dart at a dart board and just seeing what may land.”

Geography and regulatory barriers made accessing expert care harder. Michael and Naomi were limited in their ability to consult ultra-rare cancer specialists across the country—even virtually—because they lived in a state that was not part of an interstate medical licensure agreement. Desperate for guidance, the family drove 4 hours from Albuquerque to El Paso, Texas on three occasions, just to sit in a parking lot for a Zoom call with a specialist licensed in that state.

In November 2021, the family relocated to California for care at Lucile Packard Children’s Hospital Stanford. Naomi left a new teaching job, Michael took a leave of absence from his nonprofit work, and Santiago was pulled from preschool. “Our lives were upended through and through,” Michael said.

Throughout treatment, the impact on Santiago weighed heavily on the family. While Sebas spent long stretches in the hospital, Santiago often stayed with his grandmother. “As a 3-year-old, he didn’t know what was going on or why he was being left alone by his parents for so long,” Michael said. “Siblings are also warriors; oftentimes their story is overlooked in a cancer journey.”

Sebas underwent an intensive treatment course, including 10 rounds of chemotherapy. Three months after completing treatment in May 2022, a follow-up chest CT revealed a new lung nodule—an indication the chemotherapy had not worked. Sebas underwent emergency surgery to remove the nodule, but the 3-month follow-up scan showed five additional nodules. Four of those nodules were successfully removed but subsequent 3-month follow-up scans showed three additional nodules that were too small to be safely removed. While Sebas is not considered in remission, his disease has remained stable and he continues to undergo scans every 3 months to closely monitor the remaining nodules.

Unfortunately, the chemotherapy took a significant toll. Sebas developed osteoporosis, a condition that weakens bones. In 2025 alone, he suffered five fractures from ordinary childhood falls. “We can’t shield our son from playing and being a kid,” Michael said, “but it scares us every day.”

Sebas’ family has become deeply involved in advocacy and research efforts. In early 2022, from Sebas’s hospital bed, Michael and Naomi founded cureMEC: The Myoepithelial Carcinoma Project, a nonprofit organization dedicated to advancing research, connecting families, and improving access to information for patients. Their experience reflects a growing reality that families facing rare diseases are not only participants in care but also drivers of progress.

Michael and Naomi hope to highlight the urgent need for more investment in pediatric and ultra-rare cancer research. Ultra-rare cancers like MEC receive little research funding, leaving families and clinicians without data to guide care. Less than 5 percent of the National Cancer Institute’s budget goes to pediatric cancer research. Many essential tools, such as comprehensive genetic sequencing of tumors, are not consistently covered or offered as standard care, placing additional burdens on families.

Sebas’s journey is a powerful reminder that no child with cancer should be left without a clear path forward. “It’s a very lonely feeling to know that your son was diagnosed not only with cancer, but also with an ultra-rare cancer that nobody knows anything about,” Michael said. “We learned quickly that families like ours are left to figure it out on their own. For kids around the country who are facing this devastating diagnosis, they deserve more.”