Hawaii patients spent more than $230 million on cancer care outside the state from 2021 to 2023, according to a new University of Hawaii Cancer Center study that researchers say underscores the financial strain created when patients must travel for specialized treatment.

According to the university, the study analyzed de-identified commercial insurance claims filed through Hawaii Medical Service Association by Hawaii residents receiving cancer treatment.

Researchers found that certain patients, particularly those with complex cancers such as leukemia, lymphoma and brain tumors, were more likely to need out-of-state care.

“Hawaii represents the most geographically isolated health system in the country, located approximately 2,400 miles from the continental mainland,” the study said. “Although comprehensive oncology services are available within the state, certain high-complexity subspecialty services, advanced therapeutics, and clinical trial opportunities may require patients to seek care outside Hawaii.”

The study found that out-of-state cancer care expenditures totaled about $58 million in 2021, rose to $94 million in 2022 and reached nearly $79 million in 2023.

Breast cancer accounted for the largest total amount spent on out-of-state care, at $59.5 million, due to its high prevalence, researchers said. It was followed by leukemia at $46.4 million, lymphoma at $21.5 million, prostate cancer at $14.9 million and pulmonary cancer at $14 million.

Leukemia had the highest proportion of out-of-state spending for treatment, at 39%, followed by lymphoma at 29%, central nervous system tumors at 27%, multiple myeloma at 21% and breast cancer at 21%.

Dr. Hideko Yamauchi, director of clinical affairs at the UH Cancer Center and principal investigator for the study, said patients who travel for specialized cancer care face expenses beyond medical bills, including airfare, lodging, time away from work and the emotional strain of being treated far from family and other support.

“A concern raised by these findings is that the patients we can see in the data are only the ones who successfully traveled,” Yamauchi said in a news release. “The patients we worry about are the ones we cannot see in this data — those who did not travel and faced barriers to accessing specialized care.”

The study examined only direct medical costs paid through HMSA insurance claims. It did not include claims with other insurers or additional costs borne by patients and families, such as airfare, lodging, meals, lost income or caregiver time.

Researchers said the findings point to a need for expanded cancer care in Hawaii, including high-demand specialty services, advanced diagnostics, clinical trials and tele-oncology.

Dr. Naoto T. Ueno, director of the UH Cancer Center and a co-author of the study, said the center’s new Ho’ōla Early Phase Clinical Research Center is intended to increase access to advanced cancer care in the state.

“Ho’ōla EPCRC will give qualifying Hawaii patients the opportunity to receive cutting-edge, first-in-Hawaii Phase I clinical trial treatments here at home, without leaving their families and communities to travel to the U.S. mainland,” Ueno said.

The study was selected as an electronic abstract for the American Society of Clinical Oncology annual meeting in May in Chicago.