Antitumor therapy is taking into consideration the possibility to use natural nanovesicles, called exosomes, as an ideal delivery for both old and new anti-cancer molecules. This with the attempt to improve the efficacy, at the same time reducing the systemic toxicity of physical, chemical, and biological molecules. Exosomes may in fact increase the level of biomimetism, through simulating what really occurs in nature. Although extracellularly released vesicles include both microvesicles (MVs) and exosomes, only exosomes have the size that may be considered suitable for potential use to this purpose, also by analogy with the diffusely used artificial nanoparticles, such as lyposomes. In fact, recent reports have shown that exosomes are able to interact with target cells within an organ or at a distance using different mechanisms. Much is yet to be understood about exosomes, and currently, we are looking at the visible top of an iceberg, with most of what we have to understand on these nanovesicles still under the sea. In fact, we know that exosomes released by normal cells always trigger positive effects, while those released by cells in pathological condition, such as tumors may induce undesired, dangerous, and mostly unknown effects. To date we have many pre-clinical data available and possibly useful to think about a strategic use of exosomes as a delivery nanodevice in cancer treatment. However, this review wants to critically emphasize two important points actually hampering further discussion in the field : (i) the clinical data are virtually absent at the moment ; (ii) the best cellular source of exosomes to be used to deliver drugs is really far to be defined. Facing off these two points may well facilitate the attempt to figure out this very important issue for improving at the best future anti-cancer treatments.

抗肿瘤治疗正在考虑使用天然纳米囊泡（称为外泌体）的可能性，作为新旧抗癌分子的理想递送方式。这是为了提高疗效，同时降低物理、化学和生物分子的全身毒性。外泌体实际上可以通过模拟自然界中真实发生的事情来提高仿生学水平。尽管细胞外释放的囊泡包括微泡 (MV) 和外泌体，但只有外泌体的大小可被认为适合潜在用于此目的，也类似于广泛使用的人工纳米颗粒，例如脂质体。事实上，最近的报道表明，外泌体能够使用不同的机制与器官内或远处的靶细胞相互作用。关于外泌体还有很多东西有待了解，目前，我们正在观察冰山可见的顶部，我们对这些纳米囊泡的大部分了解仍在海底。事实上，我们知道正常细胞释放的外泌体总是会引发积极的影响，而处于病理状态的细胞（如肿瘤）释放的外泌体可能会引起不良的、危险的和大部分未知的影响。迄今为止，我们有许多可用的临床前数据，这些数据可能有助于考虑战略性地使用外泌体作为癌症治疗中的递送纳米装置。然而，这篇综述想批判性地强调实际上阻碍该领域进一步讨论的两个要点：(i) 目前几乎没有临床数据；(ii) 用于递送药物的外泌体的最佳细胞来源还远未确定。