The efficacy of
chemotherapy in digestive
neuroendocrine tumors (NET) depends on primary site and histological differentiation. Many reports have suggested a superior activity of
chemotherapy for pancreatic NET than for metastatic
carcinoid tumors with response rates ranging from 40 to 60% compared to 20%. The standard
chemotherapy for pancreatic NET is a combination of
adriamycin and
streptozocin and to a lesser extent a combination of
5FU and
streptozocin. In contrast, there is no clear standard
chemotherapy for
carcinoid tumors and if most oncologists use a combination of
5FU and
streptozocin in the case of advanced, progressive and nonresectable
carcinoid tumors, the results are mostly poor and the benefit seldom counterbalances its toxicity. In these
carcinoid tumors the combination of hepatic artery
ischemia alternating with
chemotherapy has given impressive results in one study, which, however, have never been confirmed.
Tumor cell differentiation is a major prognostic factor and some reports have suggested a higher chemosensitivity for undifferentiated or poorly differentiated NET with
tumor response rates ranging from 41 to 69% when a VP16-CDDP combination is used. This chemosensitivity is, unfortunately, as in small cell lung
carcinomas, of short duration. Related to this special problem and the number of other active treatments in NET, the place of
chemotherapy always has to be discussed in a multidisciplinary fashion. Surgical excision, chemoembolization,
interferons and
somatostatin analogues have to be emphasized and eventually combined with
chemotherapy, especially in slowly growing
tumors. New active
chemotherapy regimens have to be tested clearly in this orphan group of
tumors which does not hold much interest to the
pharmaceutical companies.