Conference Coverage

CT of chest, extremity effective for sarcoma follow-up



BOSTON – CT scans appear to be effective for detecting local recurrences and pulmonary metastases in patients treated for soft-tissue sarcomas of the extremities, for about a third less than the cost of follow-up with MRI.

In a retrospective study by Dr. Allison Maciver and her colleagues, among 91 patients with soft-tissue sarcomas of the extremity followed with CT, 11 patients had a total of 14 local recurrences detected on CT, and 11 of the recurrences were in patients who were clinically asymptomatic.

Surveillance CT also identified 15 cases of pulmonary metastases, and 4 incidental second primary malignancies, Dr. Maciver of the Roswell Park Cancer Institute in Buffalo, N.Y., and her coinvestigators found, and there was only one false-positive recurrence.

The benefits of CT over extremity MRI in this population include decreased imaging time, lower cost, and a larger field of view, allowing for detection of second primary malignancies, she noted in a poster session at the annual Society of Surgical Oncology Cancer Symposium.

Many sarcomas of the extremities are highly aggressive, and timely detection of local recurrences could improve chances for limb-sparing salvage therapies. Although MRI has typically been used to follow patients with sarcomas, it is expensive and has a limited field of view, Dr. Maciver said.

In addition, the risk of pulmonary metastases with some soft-tissue sarcomas is high, necessitating the use of chest CT as a surveillance tool.

To see whether CT scans of the chest and extremities could be a cost-effective surveillance strategy for both local recurrences and pulmonary metastases, the investigators did a retrospective study of a prospective database of patients who underwent surgical resection for soft-tissue sarcomas of the extremities from 2001 through 2014 and who had CT as the primary follow-up imaging modality.

They identified a total of 91 high-risk patients followed for a median of 50.5 months. The patients had an estimated 5-year freedom from local recurrence of 82%, and from distant recurrence of 80%. Five-year overall survival was 76%.

Of the 15 patients found on CT to have pulmonary metastases, there were 4 incidentally discovered second primary cancers, including 1 each of non–small cell lung cancer, pancreatic adenocarcinoma, Merkel cell carcinomatosis, and myxofibrosarcoma. There were no false-positive pulmonary metastases.

The estimated cost of 10 years of surveillance, based on 2014 gross technical costs, was $64,969 per patient for chest CT and extremity MRI, compared with $41,595 per patient for chest and extremity CT surveillance, a potential cost savings with the CT-only strategy of $23,374 per patient.

The investigators said that the overall benefits of CT, including the cost savings in an accountable care organization model, “appear to outweigh the slightly increased radiation exposure.”

The study was internally funded. The authors reported having no relevant financial disclosures.

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