ASCO — Percutaneous radiofrequency ablation (RFA) of lung metastases of colorectal cancer may be a useful treatment option in patients who are not candidates for surgery, but the benefit varies with the size of the metastases, Tristan D. Yan, MBBS, reported at the 2006 American Society of Clinical Oncology Annual Meeting (abstract 3502). Dr. Yan and his colleagues at St. George Hospital, Sydney, Australia, conducted a prospective, nonrandomized phase II study of percutaneous RFA among 55 adults with pulmonary metastases of colorectal cancer who were not candidates for surgery or who refused surgery. Patients must have undergone complete resection of their colorectal cancer and any liver metastases.
RFA was not associated with any deaths, Dr. Yan said, but 42% of patients had at least one complication. With a median follow-up of 24 months, he said, 66% of patients experienced a progression of their cancer at any systemic site. Median progression-free survival (PFS) was 15 months. In multivariate analysis, only a lung lesion measuring greater than 3 cm was independently associated with an increased risk of progression (HR 5.1).
Overall, 38% of patients had a local progression. The median local PFS had not been reached at the time of analysis. In multivariate analysis, the two factors independently associated with a higher risk of local progression were a lung lesion measuring greater than 3 cm (HR 8.3) and a CEA level of more than
5 ng/mL at 1 month after RFA (HR 3.5). Median overall survival was 33 months, with 1-, 2-, and 3-year rates of 85%, 64%, and 46%, respectively. In multivariate analysis, only a lung lesion greater than 3 cm was independently associated with increased risk of death (HR 4.5).
"The 55 patients may not be a true representation of the target population," Dr. Yan said. "We see more patients presenting with colorectal liver metastases before their lung metastases in our hospital. A lot of these patients were judged to be nonsurgical candidates because they had two-organ metastases." Another limitation was the difficulty of assessing the response to RFA. "During the early period after RFA, there is a large area of consolidation that gradually resolves over time. Especially during the first 3 months, it is difficult to assess whether the tumor has progressed," he said.
