GASTRIC B-CELL MUCOSA-ASSOCIATED LYMPHOID-TISSUE (MALT) LYMPHOMA - CLINICOPATHOLOGICAL STUDY AND EVALUATION OF THE PROGNOSTIC FACTORS IN 143 PATIENTS

Background: Gastric MALT lymphoma can be histologically classified int o two groups, low-grade (LG) and high-grade (HG); however, their natur al history is poorly understood. We have studied a large retrospective series aiming to confirm whether the histological groups confer diffe rent clinical features and behavior and to analyze the prognostic fact ors in these patients. Patients and methods: A series of 143 gastric B -cell MALT lymphomas is reported. Eighty-four were low-grade lymphomas (LG) and 59 were high-grade lymphomas (HG). Median follow-up was 36 m onths. The clinical and analytical parameters of the 84 LG patients we re compared with those of the 59 HG patients. In the patients who had been operated on, the pathological features (macroscopical patterns, t umor size, involvement of resection margins, degree of parietal invasi on and involvement of abdominal lymph nodes and adjacent viscera) of t he LG patients were compared with those of the HG patients. The sites of relapses were studied. In the 132 treated and followed-up patients the influence of the treatment and that of clinical, analytical and pa thological features on survival were investigated with the Kaplan and Meier and log-rank tests. To identify the factors with independent inf luence on survival, a Cox model was fitted for the whole series and se parately for 53 HG patients. Results: HG group differed from the LG gr oup by a significantly higher frequency of weight loss at presentation , palpable abdominal mass, hepatomegaly, peripheral lymphadenopathy, e levated serum LDH, higher incidence of stage III-IV and tumor/mass pat terns in the endoscopy and in the gastrectomy specimen. The tumor was significantly larger in the HG group than in the LG and the deeper inv asion of the gastric wall, the higher frequency of infiltration of the abdominal lymph nodes and the visceral extension were also significan t in the HG group. Complete remission (CR) was achieved in 91% of the patients of the LG group, but was significantly lower, 70%, in the HG group. Relapses occurred in the stomach and also in non-MALT sites. In 132 treated and followed-up patients, elevated serum LDH, absence of CR, HG group and stage III-IV were associated with a worse survival. I n the Cox multivariate model, stage was the only variable influencing survival, although stage was related to the histological grade. In the HG group, stage was also an independent significant risk factor, wher eas treatment with surgery, chemotherapy or both was not. In the 103 p atients treated with surgery, a worse survival was associated with the involvement of the resection borders, depth of the infiltration of th e gastric wall, dissemination to distant abdominal nodes and adjacent organs, but not with the addition of chemotherapy. Conclusions: Histol ogical classification into LG and HG separates distinctive groups of g astric MALT lymphoma that show striking clinical and prognostic differ ences. Besides histological grade, stage is the most important prognos tic feature.