Growth of newly diagnosed, untreated metastatic gastrinomas and predictors of growth patterns.

PURPOSE The growth pattern of untreated metastatic neuroendocrine tumors is unknown. This uncertainty contributes to the disagreement regarding timing and could effect evaluation of the efficacy of antitumor treatment. The purpose of this study was to determine the growth rate of untreated hepatic metastatic gastrinoma and to identify its predictors. PATIENTS AND METHODS Nineteen patients with histologically proven metastatic gastrinoma in the liver with Zollinger-Ellison syndrome were studied. Conventional imaging studies were performed initially and at 4- to 6-month intervals before any treatment. Metastases growth rates were calculated and correlated with laboratory and clinical parameters, as well as tumor extent on initial tumor assessment. RESULTS Twenty-six percent of patients (five of 19) demonstrated no growth over a mean follow-up time of 29 months, 32% (six of 19) had slow growth (1% to 50% increase in volume per month) over a 19-month period, and 42% (eight of 19) had rapid growth (> 50% volume increase per month) over an 11-month period. In patients with rapid growth, 62% died; 0% of the no-growth or slow-growth group died. No clinical or laboratory parameter correlated with growth rate, except the rate increase in fasting serum gastrin and the presence of bilobar liver or bone metastases. The growth rate was highly predictive of death from tumor. CONCLUSION The growth rate of metastatic gastrinoma varies markedly in different patients and 26% demonstrate no growth. The growth rate needs to considered in the determination of when and in whom antitumor therapy is initiated, as well as in the assessment of response to tumoricidal therapies.