LOS ANGELES – The size of anorectal gastrointestinal stroma tumors is the most important determinant of survival following resection, results from an analysis of national data showed.
In addition, preoperative chemotherapy appears to improve survival rate in patients with tumors 5 cm in size or greater.
Anorectal gastrointestinal stromal tumors (GISTs) are rare, making up about 3% of all GIST cases, lead study author Dr. Alexander T. Hawkins reported at the annual meeting of the American Society of Colon and Rectal Surgeons. However, “optimal management remains elusive with questions regarding the role of local excision and the use of preoperative chemotherapy,” said Dr. Hawkins of the section of colon and rectal surgery at Washington University in St. Louis.
In an effort to determine the impact of tumor size, the benefits of using neoadjuvant imatinib, and the impact of a surgical approach, the researchers used the National Cancer Database (NCD) to identify 333 cases of anorectal GIST from 1998 through 2012. The NCD collects data from more than 1,500 cancer centers in the United States, and it’s estimated to account for 70% of all newly diagnosed cases of cancer.
The mean age of patients was 62 years, the median tumor size was 4 cm, 47% had a high-grade tumor, six presented with metastatic disease, and the overall 5-year survival rate was 78%. Of the 333 cases, 163 underwent local excision, 158 underwent radical excision, and 12 had no resection data. Of the radical excision cases, 89 had tumors of 5 cm in size or larger, while 69 had tumors of less than 5 cm in size.
Tumors treated with local resection tended to be smaller, compared with those treated by radical resection (a median of 2.5 cm vs. a median of 6.2 cm, respectively; P less than .001). Bivariate analysis revealed that patients who underwent treatment with local resection had a shorter hospital length of stay (a median of 0 vs. 7 days; P less than .001), but similar rates of 30-day readmission (5.5% vs. 4.4%, P = .65), 30-day mortality (0.6% vs. 1.3%, P = .54) and 90-day mortality (1.2% vs. 2.5%, P = .38). The rates of 5-year survival were higher in the local resection group (80.1% vs. 74.1%, P = .04).
Multivariable survival analysis revealed that advanced age (HR, 2.41) and tumor size greater than 5 cm (HR 2.48; P = .004) were associated with increased mortality. When Dr. Hawkins and his associates evaluated the role of chemotherapy, patients who received preoperative chemotherapy had a 5-year survival of 76.7%, compared with 50.4% in those who did not (P = .04). However, in this same group, chemotherapy did not improve the rate of margin-negative resection (80% vs. 78.6%, P = .88).
Dr. Hawkins also reported that, compared with patients who underwent radical resection, those who underwent local resection had lower rates of preoperative chemotherapy (9.2% vs. 25.3%, respectively; P = .0001) and smaller median tumor size (2.5 cm vs. 6.2 cm, P less than .0001). For tumors smaller than 5 cm in size, there was no difference in 5-year survival by surgical approach (82.3% vs. 82.6%, P = .71).
“Size in the most important determinant of survival after resection of anorectal GIST,” Dr. Hawkins concluded. “For smaller tumors, local excision may be an adequate therapy. Perhaps our most important finding is that preoperative chemotherapy appears to result in improved survival for large tumors treated with radical resection.”
Dr. Hawkins reported having no relevant financial disclosures.