The Ludwig Center for Cancer Genetics and Therapeutics, The Swim Across America Laboratory at Johns Hopkins, Baltimore, MD 21287, USA.
Sci Transl Med. 2013 Jan 9;5(167):167ra4. doi: 10.1126/scitranslmed.3004952.
Papanicolaou (Pap) smears have revolutionized the management of patients with cervical cancers by permitting the detection of early, surgically curable tumors and their precursors. In recent years, the traditional Pap smear has been replaced by a liquid-based method, which allows not only cytologic evaluation but also collection of DNA for detection of human papillomavirus, the causative agent of cervical cancer. We reasoned that this routinely collected DNA could be exploited to detect somatic mutations present in rare tumor cells that accumulate in the cervix once shed from endometrial or ovarian cancers. A panel of genes that are commonly mutated in endometrial and ovarian cancers was assembled with new whole-exome sequencing data from 22 endometrial cancers and previously published data on other tumor types. We used this panel to search for mutations in 24 endometrial and 22 ovarian cancers and identified mutations in all 46 samples. With a sensitive massively parallel sequencing method, we were able to identify the same mutations in the DNA from liquid Pap smear specimens in 100% of endometrial cancers (24 of 24) and in 41% of ovarian cancers (9 of 22). Prompted by these findings, we developed a sequence-based method to query mutations in 12 genes in a single liquid Pap smear specimen without previous knowledge of the tumor's genotype. When applied to 14 samples selected from the positive cases described above, the expected tumor-specific mutations were identified. These results demonstrate that DNA from most endometrial and a fraction of ovarian cancers can be detected in a standard liquid-based Pap smear specimen obtained during routine pelvic examination. Although improvements need to be made before applying this test in a routine clinical manner, it represents a promising step toward a broadly applicable screening methodology for the early detection of gynecologic malignancies.
巴氏涂片法通过检测早期、可通过手术治愈的肿瘤及其前体，彻底改变了宫颈癌患者的管理方式。近年来，传统的巴氏涂片法已被一种基于液体的方法所取代，这种方法不仅允许细胞学评估，还允许收集 DNA 以检测人乳头瘤病毒（HPV），这是宫颈癌的致病因子。我们推测，这种常规采集的 DNA 可用于检测从子宫内膜癌或卵巢癌脱落并在宫颈中积累的罕见肿瘤细胞中存在的体细胞突变。我们利用来自 22 例子宫内膜癌的全新全外显子组测序数据和先前发表的其他肿瘤类型的数据，组建了一组在子宫内膜癌和卵巢癌中常见突变的基因。我们使用该基因集在 24 例子宫内膜癌和 22 例卵巢癌中寻找突变，并在所有 46 例样本中发现了突变。通过一种灵敏的大规模平行测序方法，我们能够在 100%的子宫内膜癌（24/24）和 41%的卵巢癌（22/46）的液体巴氏涂片标本的 DNA 中识别出相同的突变。鉴于这些发现，我们开发了一种基于序列的方法，可以在不了解肿瘤基因型的情况下，在单个液体巴氏涂片标本中查询 12 个基因的突变。当应用于从上述阳性病例中选择的 14 个样本时，识别出了预期的肿瘤特异性突变。这些结果表明，在常规盆腔检查中获得的标准液体巴氏涂片标本中，可以检测到大多数子宫内膜癌和一部分卵巢癌的 DNA。虽然在常规临床应用之前需要进行改进，但这代表了朝着广泛适用于妇科恶性肿瘤早期检测的筛查方法迈出了有前途的一步。
