UI sarcoma study suggests better outcomes at high-volume centers

Sarcoma patients treated at high-volume medical centers may have higher survival rates than those treated at low-volume centers, according to a new analysis of cancer-treatment data by a team of University of Iowa researchers.

The study, published April 6 in the Journal of Surgical Oncology, used data from the National Cancer Database (NCDB) to examine the effects of volume—the number of sarcoma patients treated at a hospital—on the outcomes of patients treated for non-metastatic soft tissue sarcoma of the upper and lower extremity.

In a comparison of two groups of patients, the UI research team found the group treated at high-volume hospitals had survival rates of 87 percent at 2 years, 73 percent at 5 years, and 58 percent at 10 years, while the group treated at low-volume hospitals had survival rates of 84 percent, 68 percent, and 53 percent for the same periods.

The role of appropriate specialty care

Benjamin Miller, MD, UI associate professor of orthopedics and rehabilitation and corresponding author of the study, says the findings are an important step toward raising awareness about the role that access to appropriate health care facilities can play, especially for a disease like sarcoma that requires the kind of multidisciplinary attention that larger centers are better equipped to offer.

“The purpose of our study was to investigate the relationship between access—treatment at a center based on convenience—and regionalization—treatment at a center based on expertise—in sarcoma, a rare and challenging cancer. There are theoretical arguments for both sides,” Miller says.

“Perhaps it is better to see a health care provider locally, where appointments are easy and travel time is minimal. Alternatively, it may be more important to be treated at a hospital with dedicated specialists and higher volumes. We found that the experience of the treating hospital does matter and supports the axiom that patients with a sarcoma should be treated at sarcoma centers.”

The research team assembled a study population of 7,874 sarcoma cases by querying anonymized NCDB data from 1998 to 2012 for patients who were 18 or older, had been diagnosed with soft tissue sarcomas of the upper or lower extremity, and had their tumors surgically removed. Patients who had metastatic sarcoma or who had additional cancers were excluded, as were patients whose records were incomplete.

Out of 1,200 centers that had treated at least one qualifying soft tissue sarcoma case in one year from 1998 to 2012, 22 had an average annual volume of 10 or more cases and were classified as high-volume. Those high-volume centers treated 2,437 of the patients in the cohort, with an average of 14.6 treated annually, while the low-volume centers treated 5,437 patients, with an average of 1.5 treated annually.

The research team then devised a propensity score based on patient demographics and tumor characteristics to identify 2,437 low-volume-center cases that were most similar to the 2,437 cases treated at high-volume centers. Comparisons of those two groups’ treatment—including treatment decisions, treatment outcomes, and survival rates—informed the study’s results.

Previous hospital-volume-related studies of extremity soft tissue sarcoma survival rates have shown no consistent or significant differences in overall survival rates. With the use of propensity score matching, the UI team attempted to account for differences between the two groups, such as the higher rate of lower-grade and smaller tumors treated at low-volume centers, that could have a bearing on survival rates but were not reflected in earlier studies.

Differences in surgical results

One of the most notable treatment-outcome differences the researchers found was that high-volume centers recorded lower rates of positive margins—that is, instances in which some tumor tissue remained in the patient after surgery.

“In most cases, the goal of sarcoma surgery is a negative margin, which means there are no tumor cells remaining at the surgery site” Miller says. “A higher rate of positive margins could suggest suboptimal planning or performance, and that puts the patient at greater risk for recurrence of the sarcoma.”

High-volume centers were also more likely to use radiation and chemotherapy, though determining whether that had a positive effect on outcomes was beyond the scope of the study.

In addition to Miller, the UI research team included Yubo Gao, PhD, Varun Monga, MBBS, Munir Tanas, MD, Mohammed Milhem, MBBS, and first author Tyler Abarca, a medical student in the UI Carver College of Medicine.