- Actor Sam O’Neill has died suddenly and unexpectedly at the age of 78, his family announced.
- O’Neill has been treated for the past 4 years for angioimmunoblastic T-cell lymphoma, a rare fast-growing type of blood cancer.
- No cause of death has been released, but O’Neill’s family said the star of the 1993 film Jurassic Park was cancer-free when he died.
Actor Sam O’Neill has died following a 4-year battle with a rare, aggressive form of cancer that can be difficult to diagnose and treat, angioimmunoblastic T-cell lymphoma.
O’Neill’s family announced that the 78-year-old actor had died suddenly and unexpectedly on Monday.
No cause of death was given, but family members said O’Neill was believed to be cancer-free when he died in Sydney, Australia.
In 2022, O’Neill, best-known for his role in the Jurassic Park film franchise, was diagnosed with angioimmunoblastic T-cell lymphoma, a rare type of blood cancer that affects white blood cells known as T-cells. The fast-growing blood cancer can spread to the lungs, liver, or bone marrow.
In his memoir, “Did I Ever Tell You This?”, O’Neill wrote that doctors had initially diagnosed some swollen glands in his neck as “undetected COVID.” Eventually, a PET scan revealed O’Neill had the rare lymphoma.
O’Neill underwent four rounds of chemotherapy. In late 2023, he announced on Instagram that his cancer had been in remission for 8 months.
In a later interview, he added that he still required infusions every 2 weeks.
In an April 2026 interview, O’Neill said he was cancer-free. He added he had also been treated with CAR-T cell therapy, a type of immunotherapy treatment that genetically changes the body’s immune cells so they can fight cancer.
The median age for diagnosis of AITL is 65 years.
Symptoms from AITL include fatigue, high fever, night sweats, and skin rash. The symptoms can sometimes be similar to autoimmune diseases.
Diagnosis requires a biopsy of tumor tissue. Additional exams such as blood tests, CT scans, bone marrow biopsies, and PET scans may also be used.
AITL affects immune-regulating cells, so it can cause immune system malfunction as well as tumor growth.
The exact cause of AITL isn’t known, but it can be driven by genetic mutations in stem cells as well as secondary mutations in genes that regulate how DNA is used. Many AITL cases involve the Epstein-Barr virus, which can infect non-cancerous cells that surround the AITL-affected T cells.
Swaminthan Iyer, MD, a professor of lymphoma-myeloma at the UT MD Anderson Cancer Center in Texas, said AITL presents many challenges.
“Angioimmunoblastic T‑cell lymphoma (AITL) can be a challenging disease to diagnose and treat,” he told Healthline.
“AITL can go undiagnosed for some time,” Iyer explained. “In many cases, the disease presents with non-specific symptoms such as skin rash, diarrhea, weight loss, and swelling of the lymph nodes. Because these symptoms are not unique to AITL, the diagnosis can be difficult to pinpoint.”
“In addition, the biopsies themselves can be challenging to interpret and often require expert histopathology to confirm the diagnosis,” he added. “As a result, time may sometimes be lost navigating the diagnostic process and ruling out other conditions.”
Iyer noted that initial treatments can help control the disease for 12 to 15 months.
“However, the lymphoma almost always recurs and requires additional treatment,” he noted.
Iyer added that there are clinical trials that are exploring “novel therapeutic pathways” in which patients can be enrolled.
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