Einhorn L
Oncodev Biol Med. 1983;4(3):219-29.
On the basis of the following literature observations, a hypothesis is advanced that the development of cancer is actively inhibited during embryonic life. Although the processes of cell differentiation and proliferation are--without comparison--most pronounced during embryonic life, cancer is rarely found in the newborn and is seldom a cause of neonatal death or spontaneous abortion. Attempts to induce cancer in early-stage animal embryos by irradiation or by transplacental chemical carcinogenesis have been unsuccessful, even when exposed animals have been observed throughout their life-time. After the period of major organogenesis, however, the embryos become susceptible to carcinogenesis. In humans, the most common embryonic tumors arise in tissues which have an unusually late ongoing development and are still partly immature at or shortly before birth. For many human embryonic tumors the survival rates are higher, and spontaneous regression more frequent, in younger children, i.e. prognosis is age-dependent. Thus, although cancer generally appears in tissues capable of proliferation and differentiation, induction of malignancy in the developmentally most active tissues seems to be beset with difficulty. One possible explanation for this paradox could be that cancer is controlled by the regulators influencing development, regulators that are most active during embryonic life.
基于以下文献观察结果，提出一个假说：在胚胎期，癌症的发生受到积极抑制。尽管细胞分化和增殖过程在胚胎期最为显著，但新生儿中很少发现癌症，且癌症很少是新生儿死亡或自然流产的原因。即使对经照射或经胎盘化学致癌处理的早期动物胚胎进行终生观察，试图诱导其发生癌症的尝试也未成功。然而，在主要器官发生期之后，胚胎变得易患癌症。在人类中，最常见的胚胎肿瘤发生在发育异常延迟且在出生时或出生前不久仍部分未成熟的组织中。对于许多人类胚胎肿瘤，年幼儿童的生存率更高，自发消退更频繁，即预后与年龄有关。因此，尽管癌症通常出现在能够增殖和分化的组织中，但在发育最活跃的组织中诱导恶性肿瘤似乎存在困难。对此矛盾的一种可能解释是，癌症受影响发育的调节因子控制，这些调节因子在胚胎期最为活跃。
