TUESDAY, April 25, 2006 (HealthDay News) -- Researchers have gained insight into the diagnosis and treatment of pseudomyxoma peritonei, a rare form of cancer that starts in the appendix and can spread to the lining of the abdominal cavity.
The condition may be more dangerous than previously assumed, the researchers concluded.
"Our study suggests that tumors of the appendix that have spread through the abdominal cavity all qualify as cancer. Previously, some of the tumors were classified as 'benign,' which we believe gives a false sense of how the tumor will behave," principal investigator Dr. Robert F. Bradley, a pathology resident at Wake Forest University Baptist Medical Center in Winston-Salem, N.C., said in a prepared statement.
"Because it is so rare -- less than 0.1 percent of appendices are removed for cancer -- the disease has been plagued with controversy and confusing terminology," he said.
Currently, these tumors are classified into three general categories: high-grade cancer; low-grade cancer; and benign. Normally, all patients receive the same treatment -- surgery to remove the tumor and infusion of heated chemotherapy drugs into the abdominal cavity. The grade of the tumor indicates how the patient will respond.
Bradley and his colleagues studied 101 patients with pseudomyxoma peritonei that originated from the appendix who were treated at Wake Forest from 1993 to 2005. While patients with benign and low-grade tumors had similar one-year, three-year, and five-year survival rates, those with high-grade tumors had significantly worse survival.
"Hopefully, this will help resolve the confusion in diagnosis," Bradley said. "Our study shows that there is no separate 'benign' variant of the disease. Instead, physicians should expect those tumors that look 'benign' microscopically to behave like low-grade cancer. We now combine those cases into one diagnosis of low-grade carcinoma, for which the prognosis should be equally favorable with adequate treatment."
The way this disease is diagnosed affects how it is viewed and treated.
"We hope this will lead to a more standardized diagnosis so that these patients' doctors understand exactly what it means," Bradley said.
The study appears in the May issue of the American Journal of Surgical Pathology.
For more on pseudomyxoma peritonei, head to the U.S. National Organization for Rare Disorders.