Clinical, pathologic, and immunohistochemical characteristics of gastrointestinal stromal tumors of the colon and rectum: implications for surgical management and adjuvant therapies.
BACKGROUND
This study was designed to review the clinical characteristics of surgically treated gastrointestinal stromal tumors of the colon and rectum, evaluate their immunohistochemical and pathologic features based on the current National Institutes of Health criteria, and correlate clinicopathologic findings with the subsequent clinical course.


METHODS
Patient and disease characteristics at presentation, pathologic features, surgical management, and clinical outcomes of 18 patients with gastrointestinal stromal tumors (4 colon and 14 rectum) diagnosed and primarily treated at our institution between 1979 and 2004 were evaluated.


RESULTS
Tumors were classified on basis of size and mitotic rate according to current National Institutes of Health recommendations: 67 percent (n = 12) were high-risk, 5 percent (n = 1) were intermediate-risk, 17 percent (n = 3) were low-risk, and 11 percent (n = 2) were very low-risk gastrointestinal stromal tumors. Fifteen of 18 tumors were KIT-positive. The three KIT-negative tumors were platelet-derived growth factor receptor alpha positive. All patients with colonic gastrointestinal stromal tumors (n = 4) underwent segmental resection, whereas patients with rectal gastrointestinal stromal tumors had local excision (n = 5) or radical resection (n = 9). Sixty-six percent (8/12) of patients with high-risk colorectal gastrointestinal stromal tumors developed metastases. None of the patients (n = 6) with intermediate-risk, low-risk, or very low-risk gastrointestinal stromal tumors died of their disease after a median follow-up of 65 (range, 15-266) months.


CONCLUSIONS
The majority of gastrointestinal stromal tumors of the colon and rectum are high-risk. Patients with high-risk colorectal gastrointestinal stromal tumors have a significant likelihood of developing metastases that is associated with poor prognosis. These patients need to be closely followed for an extended period and should be considered for adjuvant therapy with tyrosine kinase inhibitors.
Division of Colon and Rectal Surgery, Mayo Clinic, 200 First Street SW, Rochester, Minnesota 55905, USA.
Imran
I
Hassan
Y Nancy
YN
You
Eric J
EJ
Dozois
Roman
R
Shayyan
Thomas C
TC
Smyrk
Scott H
SH
Okuno
John H
JH
Donohue
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018952:Antigens, CD34 / Q000378:metabolism; D003110:Colonic Neoplasms / Q000378:metabolism* / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D005260:Female; D046152:Gastrointestinal Stromal Tumors / Q000378:metabolism* / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009367:Neoplasm Staging; D019009:Proto-Oncogene Proteins c-kit / Q000378:metabolism; D020796:Receptor, Platelet-Derived Growth Factor alpha / Q000378:metabolism; D012004:Rectal Neoplasms / Q000378:metabolism* / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D018570:Risk Assessment
D018952:Antigens, CD34; D019009:Proto-Oncogene Proteins c-kit; D020796:Receptor, Platelet-Derived Growth Factor alpha