Lymphoma

The clinical and morphological features of gastric lymphomas can resemble those of carcinomas. Because lymphomas tend to be submucosal and to ulcerate as disease progresses, abnormalities of the stomach can be detected in up to 75% of patients. However, the diagnosis is made with contrast radiography in less than 20% of patients. In addition, endoscopic biopsies correctly diagnose lymphoma in only 40 to 60% of patients. Using biopsy techniques that obtain submucosal tissue [26,281] in conjunction with EUS [56-60], preoperative diagnosis should be possible in almost all patients. Because of the high accuracy of deep biopsy technique plus EUS staging, laparotomy should no longer be used to stage gastric lymphomas. The accuracy of EUS for depth of invasion of gastric lymphomas evaluated by EUS has been reported to be 96% for T 1, 67% for T2, 100% for T3, and 80% for T4. For N-stage evaluation, EUS sensitivity for perigastric lymph nodes was 44%, specificity was 100%, and positive and negative predictive values were 100 and 72%, respectively [57].

EUS can be used to monitor response during chemotherapy and radiotherapy [31]. Only EUS is able to demonstrate complete disappearance of intramural infiltration and reappearance of the normal 5-layer wall architecture. However, there may still be microinvasion in the submucosa that does not cause alteration of the architecture. Deep biopsy would be the only nonoperative method of determining this microinvasion. Recent studies [57] have shown that frequent repeat endoscopy with deep biopsy is important in patients in whom lymphomas are suspected but have not been diagnosable by biopsies or abnormal EUS findings. These patients, in whom endoscopic abnormalities are minimal, probably represent less than 5% of those with gastric lymphomas. In a study [59] in which patients with infiltrative gastric lymphomas were evaluated with sequential endoscopies over several months, only 33% were diagnosed on the first endoscopy with biopsy, but follow-up endoscopy plus biopsy at 4-week intervals diagnosed all but 1 patient without surgery. EUS has been shown to make a significant impact on the rate of total gastrectomy, decreasing the rate from 65 to 10% by accurately defining the area of involvement by lymphoma [56]. Because of the high accuracy of preoperative staging currently available with EUS for gastric lymphomas, selective treatment according to stage becomes a realistic option.

Prior to EUS, accurate staging was possible only through surgery, because CT scans were negative except for far advanced disease. Currently, there is no standardized, accepted therapy for primary gastric lymphomas. Although surgical resection of the lesion was an essential part of therapy in most studies, treatment of high-grade malignant lymphomas with only chemotherapy has achieved similar survival in a study reported by Salles and associates [61]. Gobbi and colleagues [62] also found no difference in survival rates between patients undergoing primary resection versus those not undergoing surgery. Considering the significant long-term morbidity and mortality associated with surgery for gastric lymphomas, the high rate of extraabdominal relapses when chemotherapy and radiotherapy are not included as part of the treatment, and, finally, the improved quality of life when the stomach is not resected, chemotherapy alone will certainly find a place in treatment of specific stages of lymphomas. Recently, a large multicentered trial showed that the treatment of choice is CHOP (cyclophosphamide/doxorubicin/vincristine/prednisone) compared with other chemotherapy regimens [63].

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