It is difficult to differentiate malignant
carcinoid tumors from benign ones early in the course of the illness. We investigated retrospectively a series of thirty-nine gastro-intestinal
carcinoids not only for primary
tumor anatomic site, macroscopic type,
tumor size, histological depth, vessel invasion and mitosis, but also for
peptide,
ectopic hormone and
oncofetal proteins by immunohistochemistry.
Carcinoids primary in the appendix or rectum rarely metastasize, but those primary in the stomach or colon grow rapidly. Those greater than 2 cm in diameter and Borrmann's type had a poor prognosis.
Carcinoids with deep penetration, vessel invasion or mitosis easily metastasize to lymph nodes or to the liver.
Peptide hormone producing
carcinoids were present in 21 of 39 (54%)
tumors, but there were no correlation between the prognosis and
peptide hormone producing patterns.
Carcinoids producing
carcinoembryonic antigen (CEA) were demonstrated in 11 of 37 (29%)
tumors. These
tumors were greater in size, more deeply penetrating and had more remarkable vessel invasion and mitosis than CEA non-producing ones. These results show that CEA producing
carcinoids grow rapidly and easily metastasize. We concluded that these findings in
carcinoid tissue appeared to be a reliable markers for
metastasis and poor prognosis.