Personalizing the radiation treatment dose for each patient with hepatocellular carcinoma (HCC) improves overall survival, compared to providing the standard dose. HCC is the most common type of primary liver cancer and a leading cause of cancer-related deaths around the world.
The findings of “Updated analysis of DOSISPHERE-01 trial: a long term analysis of overall survival”—which was selected as an SIR Abstract of the Year—will be presented 10:40 a.m. as part of Wednesday’s Plenary Session, Hall 6 in the Phoenix Convention Center.
With standard dosimetry—or amount of radiation used—the dose isn’t necessarily based on what the tumor might need to kill it, explained presenting author Etienne Garin, MD, PhD, who specializes in nuclear medicine at the Cancer Institute Eugene Marquis in Rennes, France.
“If the dose you are providing is below the tumor threshold tumoricidal dose, the cells can repair the lesions and you don’t get a cell kill,” he said.
In the DOSISPHERE-01 study, Dr. Garin and his team targeted a minimum radiation dose to the tumor of at least 205 Gy.
“If you use the standard dosimetry, in reality, you are targeting an absorbed dose to the volume of the liver you are treating. In some situations, the tumor dose will be higher than 205 Gy, but if the tumor is big, the tumor dose can be lower than 205 Gy,” Dr. Garin said. “So with personalized dosimetry you are almost sure to target the tumoricidal tumor of 205 Gy in a single treatment.”
The study stopped at its interim analysis, after 27 months of follow-up, because of the positivity of the primary endpoint (response rate). In this phase II study, researchers aimed to study the long-term overall survival (OS) of the 60 HCC patients included; the patients had at least one lesion >7cm and at least > 30 percent of hepatic reserve.
The patients were randomized, with 29 in a standard dosimetry arm, with the goal to deliver 120±20 Gy to the treated volume. And, 31 patients were in the personalized dosimetry arm with the goal to deliver at least 205 Gy to the index lesion, with 28 patients receiving the treatment in each arm.
Median OS was 22.9 months for those receiving personalized dosimetry, vs. 10.8 months for standard dosimetry.
The study showed that those who were secondarily resected after the radioembolization did not reach median overall survival. “It means that if you want to have prolonged overall survival in this population of patients, the only way to do that is to be able to downstage accurately the patients and to offer them surgery,” Dr. Garin said.
At long-term follow-up, the OS rates began to decline. “Even if you have quite good results, the overall survival rates at 4 and 5 years are quite low, except for the patients who were resected,” Dr. Garin said. “It means that for those kinds of patients, probably it will be necessary to perform treatment with a combination of treatments.”
