A Drug That Saves Stage-4 Cancer Patients — But Many Quit Treatment Because It’s Too Expensive

New Breast Cancer Drug Changes Outcomes but Raises Cost Concerns

SEOUL — A breakthrough breast cancer drug is transforming treatment outcomes for advanced-stage patients in South Korea, but high out-of-pocket costs are forcing some to abandon therapy, according to a leading oncologist.

In an interview, Professor Shin Jung-hoon of Samsung Medical Center said the antibody-drug conjugate Enhertu has dramatically improved survival and quality of life for patients with advanced breast cancer, including those previously considered untreatable.

From “One Month to Live” to Returning to Work

Professor Shin described a patient in her 50s with stage-4 breast cancer who had exhausted all available treatments and was given a one-month prognosis. After receiving Enhertu, her condition improved significantly. Two years later, she has returned to work, Shin said.

Enhertu was initially approved for HER2-positive breast cancer, but later clinical trials expanded its use to patients with HER2-low expression, a group that accounts for roughly half of all breast cancer patients.

Redefining Breast Cancer Classification

Traditionally, breast cancer was classified as HER2-positive or HER2-negative. New evidence showed Enhertu was effective even in patients previously categorized as HER2-negative but with low HER2 expression, prompting a shift in diagnostic and treatment strategies.

Clinical trials such as DESTINY-Breast04 showed that Enhertu extended progression-free survival by about five months compared with standard chemotherapy in HER2-low patients.

Not a Mild Drug, But a Powerful One

Despite being a targeted therapy, Shin emphasized that Enhertu can cause serious side effects, including lung inflammation in some patients, and requires close monitoring. However, he said its tumor response and symptom relief are often superior to conventional chemotherapy.

Cost Remains the Biggest Barrier

In South Korea, Enhertu is currently not fully covered by national health insurance, making treatment financially burdensome. Shin said that in clinical practice, about two-thirds of eligible patients choose Enhertu, while others opt for standard chemotherapy due to cost.

He stressed that survival statistics alone do not capture the drug’s impact. “Some patients live years longer with good quality of life,” he said, noting that advanced breast cancer is increasingly managed as a chronic condition rather than a terminal illness.

Calls for Insurance Coverage Expansion

Shin said wider insurance coverage would allow patients to receive the drug earlier and continue treatment longer, potentially improving outcomes for a growing number of advanced breast cancer patients.