Studies examine links between provider characteristics and mortality rates in ovarian cancer

Feb 24 2006

Two studies in the Journal of the National Cancer Institute examine whether hospital volume, surgeon experience, or surgeon specialty affect the treatment received and the risk of death following treatment among women with ovarian cancer.

Past studies have suggested that patients treated at hospitals with higher case loads or by more experienced surgeons have higher survival rates after surgery for certain types of cancer, including colorectal cancer and lung cancer. Patients may take such factors into account when making decisions about where and from whom to seek medical care.

Ovarian cancer ranks fourth in cancer death in U.S. women and was expected to have claimed more than 16,000 lives in 2004. It is typically a disease of women in their sixth or seventh decade. To examine the association between hospital case volume and procedure-specific experience of surgeons on outcomes after ovarian cancer surgery, Deborah Schrag, M.D., of the Memorial-Sloan Kettering Cancer Center in New York City, and colleagues used the Surveillance, Epidemiology, and End Results (SEER)-Medicare linked database to identify 2952 patients age 65 or older who had surgery for primary ovarian cancer between 1992 and 1999. They looked at both short-term (60-day) and longer term (2-year) mortality rates and overall survival.

The authors found that hospital case load and surgeon-specific experience were not associated with short term mortality following ovarian cancer surgery after adjustment for variation in patient clinical characteristics. They did find that longer term outcomes were somewhat more favorable for patients treated at high-volume hospitals compared with those treated at low-volume hospitals, but this difference was not of large magnitude. The magnitude of these associations was modest when the authors took into account the variation in clinical stage at diagnosis, age, and other factors among patients treated by providers with different caseloads. The strong association between high case volume and favorable outcomes seen in studies of high risk operations such as pancreatetomy, esophagectomy and lung resections was not found in this study of ovarian cancer surgery, the authors conclude.

"Although chronologic age and clinical stage dwarfed both hospital and procedure volume as factors associated with outcomes of care, even the modest volume-outcome variations we observed merit further scrutiny to understand the underlying mechanisms that enable higher-volume hospitals and surgeons to achieve more favorable surgical outcomes," the authors write.

In addition to hospital or surgeon volume, a surgeon's area of specialty may also affect patient outcomes. Previous studies have found that patients are more likely to receive the recommended surgery and treatment for ovarian cancer if they are treated by highly specialized surgeons such as gynecologic oncologists. To examine the association between surgeon specialty and patient outcome, Craig C. Earle, M.D., of the Dana-Farber Cancer Institute in Boston, and colleagues identified 3067 ovarian cancer patients in the SEER database who underwent a surgical procedure to remove ovarian cancer.

Of those patients, 33% were treated by a gynecologic oncologist, 45% by a general gynecologist, and 22% by a general surgeon. Ovarian cancer patients treated by gynecologic oncologists had the best outcomes and lowest mortality rates after surgery. Outcomes among these patients were marginally superior to those of patients treated by general oncologists, and much better than those of patients treated by general surgeons. Gynecologic oncologists were most likely to perform sufficiently extensive surgery, and were most likely to provide patients with post-operative chemotherapy when needed.

"Our data support professional societies' recommendations that it is preferable for ovarian cancer patients to be operated on by gynecologic oncologists when possible," the authors write. "Although the relative contributions of specialized training and surgeon volume to the observed improved outcomes requires further study, our results suggest that the expertise required to know how to treat a patient, i.e., to perform an appropriately extensive surgery and the postoperative chemotherapy, if indicated, is at least as important as technical skill that would be reflected in the volume-outcome relationship alone."

In an accompanying editorial, Joseph Lipscomb, Ph.D., of Emory University in Atlanta, discusses the studies' strengths, limitations, and implications for future research. He writes: "Taken together, the closely related analyses reported in these articles make several substantial contributions. They represent the first large-scale, population-based investigation in the United States of whether there are volume-outcome relationships in ovarian cancer surgery, focusing on potential effects at both the hospital level and the surgeon level." Moreover, Lipscomb writes, the paper by Earle and colleagues "may be the first ever population-based study of the impact of provider specialty on surgical outcomes and care processes in cancer that controls for both surgeon and hospital volume."