The clinical and pathologic features of 71 endodermal sinus tumors of the ovary were studied in an effort to delineate the histogenesis and biologic behavior of this neoplasm and to evaluate the efficacy of different forms of treatment. Alpha-fetoprotein (AFP) was idenitified in hyaline droplets, cell cytoplasm, and intercellular spaces of all 15 tumors examined by an immunoperoxidase technique; this supports the view that the neoplasm simulates yolk sac endoderm. There were only nine survivors among 65 patients on whom follow-up information was available; the actuarial survival was 13% at 3 years. Of the neoplasms that recurred, 93% did so within 1 year, and of those patients who died, 93% did so within 2 years. The size a n d stage of the tumor had prognostic significance, but the patient's age, the mitotic activity, and histologic pattern did not. Although 71% of the patients had Stage I tumors at the time of diagnosis, subclinical metastasis was present in 84% of Stage I patients. Triple chemotherapy (vincristine, actinomycin D, and cyclophosphamide (VAC)) employed after unilateral salpingo-oophorectomy in four patients with Stage I tumors resulted in three long-term survivals (75%). In contrast, there were only five survivors among 27 patients (19%) with Stage I neoplasms treated by surgery alone,and no survivors among 12 Stage I patients treated with combined surgery and radiation. The finding of AFP i n all tumors in which this was evaluated suggests that serum radioimmunoassay might be useful to monitor response to therapy.Cancer 38:2404-2419 1976.
NDOI)l.RSIAI. SINtIS TUMOR IS ALMOST AS C O M -E mon as dysgerminoma in girls and young women,14 but because of its relative rarity and comparatively late recognition as a specific entity, only a few small series1,9.11~16~21~37 and :;Poradie case reports3s4 describing its behavior have been published. T h e limited number of patients and the inclusion of mixtures of other types of germ cell neoplasms have precluded accumulation of extensive experience with pure endoderma1 sinus tumors. In view of their very poor prognosis when treated by surgery and radiation, a basis for comparison is necessary in the liyht of recent reports of long-term survival with surgery a n d triple ~h e r n o t h e r a p y .~~~~~~~ Evaluation of the relationship of alpha-fetoprotein is also necessary in light of the recent demonstra-
