Drug & Device Development

Particle therapy promising in liver cancer

Last Updated: 2011-05-25 9:00:13 -0400 (Reuters Health)

NEW YORK (Reuters Health) - Unlike other radiation approaches, proton and carbon ion therapy are both "closely equivalent" to hepatectomy for getting rid of liver tumors, Japanese researchers report.

Dr. Takumi Fukumoto of Kobe University Graduate School and colleagues note that resection and transplantation offer the best chance for surviving with hepatocellular carcinoma, but only 5% to 40% of patients are suitable candidates and there's a shortage of liver grafts.

Standard radiotherapy is limited because hepatic tolerance is lower than the tumoricidal dose. However, particle beam therapy can deliver higher tumor doses without increasing toxicity.

In several case series, both proton and carbon ion therapy have shown good overall survival and encouraging control rates. But more is known about the outcome of proton ion therapy than is the case for the carbon ion approach and there have been no comparative studies.

In an April 14th online paper in Cancer, the researchers examined data on 242 patients who had received proton therapy and 101 who had had carbon ion therapy. Median follow-up was for 31 months.

No comparison was made to alternative existing therapies for hepatocellular carcinoma in the study.

In all, 223 patients developed recurrences after treatment. The longest interval to local recurrence was 27 months, and all local recurrences developed within 3 years.

Five-year local control for all patients was 90.8% and overall survival was 38.2%. For proton therapy, the corresponding proportions were 90.2% and 38.0% and for carbon ion, they were 93.0% and 36.3%.

Tumor size was a risk factor for local recurrence in both therapy groups and in all patients. Child-Pugh classification was the only independent risk factor for overall survival in both groups and in all patients.

Stratified by Child-Pugh class, the five-year overall survival rates were 46.6% for A and 8.7% for B. No patients with C classification survived that long.

Local control rates for both proton therapy and carbon ion therapy exceeded 90%. Thus, say the investigators, they are superior to conformal radiotherapy which yields local control rates of 40% to 66%. Such therapy is also more likely to prompt radiation-induced liver disease.

Despite similar results, the researchers believe that carbon ion therapy when further developed will have a major role in treatment of patients with tumors near to the gut or in whom liver function has deteriorated.

However, they point out that "carbon ion therapy requires huge economic resources, and this issue should be resolved in the future."

"Both therapies have great advantages in treating hepatocellular carcinoma, a condition that is a contraindication for other local therapies," the research team concludes.

SOURCE: http://bit.ly/j9Hk1X

Cancer 2011.