Clinical Review

2014 Update on ovarian cancer

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The ability to detect small amounts of tumor cells in blood and vaginal specimens offers big advances in diagnosis and treatment for this deadly malignancy

In this article:

What mutations are we looking for?

Ovarian and endometrial cancer cells detected in the vagina

Circulating tumor cells—the future of cancer management?


 

References

Ovarian cancer remains the deadliest gynecologic malignancy in the United States, with more than 22,000 women newly diagnosed and more than 14,000 deaths each year. We have made slow progress in terms of survival with new drugs and applications, such as intraperitoneal chemotherapy combined with more aggressive cytoreductive efforts. Five-year survival rates have increased—from 36% to 44%—since the late 1970s.1 To make the leap from molecular genetics to successful screening, early diagnosis, and targeted treatment, we must first:

  • Enhance our understanding of the changes that lead to ovarian cancer. Currently, malignant transformation of the fallopian tube epithelium is thought to result in high-grade papillary serous cancer.2 If this is indeed the pathologic origin of ovarian cancers, then early detection or even detection in the premalignant phase may be possible using tests of vaginal fluid. Are early detection, and even screening, possible and how would it effect treatment and survival?
  • Develop new and powerful tools to detect molecular changes that might impact treatment and survival. Just a few years ago, initial sequencing of the human genome cost more than $100 million, but DNA sequencing technologies have evolved rapidly, with current estimates at less than a few thousand dollars per genome.3 Knowing the mutations responsible for an individual’s cancer would allow for targeted, individualized treatment plans. Would one patient benefit from neoadjuvant therapy while another needs primary surgical debulking?

In this article, we highlight the historical basis and recent developments in the field of ovarian cancer, focusing on:

  • etiologic heterogeneity and molecular biology detection of small numbers of cancer cells in vaginal secretions and the blood stream.
  • detection of small numbers of cancer cells in vaginal secretions and the blood stream.

What mutations are we looking for?

Cancer Genome Atlas Research Network. Integrated genomic analyses of ovarian carcinoma. Nature. 2011;474(7353):609−615.

In last year’s Update, we discussed the role of The Cancer Genome Atlas (TCGA) project in endometrial cancer.4 For ovarian cancer, TCGA analyzed messenger RNA expression, microRNA expression, promoter methylation, and DNA copy number in 489 high-grade serous ovarian adenocarcinomas and the DNA sequences of exons from coding genes in 316 of these tumors.

Almost all tumors (96%) were characterized by mutations of the gene encoding TP53 in addition to statistically recurrent mutations in nine other loci, including NF1, BRCA1, BRCA2, RB1, and CDK12, although these were of low prevalence. Analyses also brought new insight regarding the survival impact of tumors containing BRCA1 or BRCA2 and CCNE1 mutations. Findings included NOTCH and FOXM1 signaling involvement in serous ovarian cancer pathophysiology as well as defective homologous recombination in approximately half of the tumors studied.

What this evidence means for practiceWith these mutations as our targets, we can screen vaginal secretions as well as blood for markers of ovarian cancer.

Ovarian and endometrial cancer cells detected in the vagina

Kinde I, Bettegowda C, Wang Y, et al. Evaluation of DNA from the Papanicolaou test to detect ovarian and endometrial cancers. Sci Transl Med. 2013;5(167):167ra4.

Erickson BK, Kinde I, Dobbin AC, et al. Detection of somatic TP53 mutations in tampons of patients with high-grade serous ovarian cancer [published online ahead of print October 2014]. Obstet Gynecol. 2014;124(5).

Ruth Graham, Papanicolaou’s cytology technician in the 1940s, first described ovarian cancer cells detected in vaginal/cervical cytology obtained from vaginal secretions.5 Current studies now demonstrate that we have technology capable of more than simple cytologic detection. We can isolate and evaluate these cancer cells in very small numbers.

Ovarian and endometrial cancer DNA identified in Pap specimenKinde and colleagues assembled a catalog of common mutations previously found in ovarian cancer as well as new data on 22 endometrial tumors. They tested 24 endometrial and 22 ovarian samples from patients with endometrial or ovarian cancers and confirmed that all 46 harbored at least some component of the common genetic changes in their catalog. Hypothesizing that the cancers likely shed cells from their surfaces, they sought to determine whether they could detect these cells among the cervical cells in a Pap smear.

These investigators used massively parallel sequencing to test DNA collected in modern liquid-based cytologic specimens for the same mutations found in the cancer cells. They found that 100% of the endometrial cancers and 41% of ovarian cancers were detectable by this method.

TP53 mutations in ovarian cancer cells detected in vaginally placed tamponWith similar technology, but a different collection method, Erickson and colleagues sought to detect tumor cells in the vagina of women with serous ovarian cancer by TP53 analysis of DNA samples collected via vaginal tampon.

Next Article:

Ovarian cancer often arises from precursor endometriosis

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