Iatrogenic endometriosis harbors somatic cancer-driver mutations

Endometriosis-Associated Ovarian Cancer: The Origin and Targeted Therapy

Endometrial cysts (ECs) are thought to be the origin of endometriosis-associated ovarian cancer (EAOC). A hypothesis that the oxidative stress of iron in cysts causes “malignant transformation of ECs” has been proposed, but this has not been verified. Several population-based studies showed that endometriosis was a risk factor but did not reflect the “malignant transformation of ECs”. A review showed that most patients were diagnosed with EAOC early in monitoring following detection of ECs, and that these cases might have been cancer from the start. Epidemiologically, EAOC was reduced by hysterectomy rather than by cystectomy of ECs. Gene mutation analyses identified oncogenic mutations in endometriosis and normal endometrium and revealed that the same mutations were present at different endometriotic lesions. It was also shown that most of the gene mutations found in endometriosis occurred in normal endometrium. Taking together, EAOC might be caused by eutopic endometrial glandular epithelial cells with oncogenic mutations that have undergone menstrual blood reflux and engrafted in the ovary, rather than by low-risk ECs acquiring oncogenic mutations and becoming malignant. This review discusses the mechanisms of EAOC development and targeted therapy based on genetic variation in EAOC with a focus on eutopic endometrium.

Endometriosis-It is not just benign

Endometriosis is a common disease, not uncommonly debilitating with severe negative impact on all domains of life for women. The long-standing approach is that endometriosis is one of many gynecological benign conditions. Nevertheless, there is a growing body of evidence linking endometriosis and invasiveness. The aim of this commentary is to address the topic of the attitude toward endometriosis as a benign disease while summarizing the current literature regarding the debate that surrounds this topic.

The mutational landscape of normal human endometrial epithelium

All normal somatic cells are thought to acquire mutations, but understanding of the rates, patterns, causes and consequences of somatic mutations in normal cells is limited. The uterine endometrium adopts multiple physiological states over a lifetime and is lined by a gland-forming epithelium1,2. Here, using whole-genome sequencing, we show that normal human endometrial glands are clonal cell populations with total mutation burdens that increase at about 29 base substitutions per year and that are many-fold lower than those of endometrial cancers. Normal endometrial glands frequently carry 'driver' mutations in cancer genes, the burden of which increases with age and decreases with parity. Cell clones with drivers often originate during the first decades of life and subsequently progressively colonize the epithelial lining of the endometrium. Our results show that mutational landscapes differ markedly between normal tissues-perhaps shaped by differences in their structure and physiology-and indicate that the procession of neoplastic change that leads to endometrial cancer is initiated early in life.

Disseminated Endometriosis and Low-Grade Endometrioid Stromal Sarcoma in a Patient with a History of Uterine Morcellation for Adenomyosis

Morcellation of benign uterine tumors allows for removal of the tumors via minimally invasive laparoscopic procedures. However, in rare cases, morcellation has been associated with upstaging of unexpected malignancies. Morcellation has also been associated with dissemination of benign pathologic processes such as endometriosis and leiomyomas. Endometrial stromal sarcoma typically arises in the uterine cavity, although cases of extrauterine endometrioid stromal sarcoma arising out of foci of endometriosis have been reported. Dissemination of endometrial stromal sarcomas can be an unintended consequence of morcellation procedures, as can dissemination of endometriosis, from which endometrioid stromal sarcomas can arise. Herein, we report a case of a 55-year-old woman who was found to have disseminated endometriosis and low-grade endometrioid stromal sarcoma, with bowel and liver parenchymal metastasis, 7 years after undergoing supracervical hysterectomy with unconfined uterine morcellation for adenomyosis. Our case highlights the potential for malignant transformation of disseminated adenomyosis/endometriosis and the importance of patient counseling and shared decision-making prior to morcellation procedures.

Abdominal wall endometriosis (a narrative review)

One of the rarest forms of endometriosis is abdominal wall endometriosis (AWE), which includes caesarean scar endometriosis. AWE remains a challenging condition because some issues related to this topic are still under debate. The increasing number of caesarean sections and laparotomies will expect to increase the rate of AWE. The current incidence in obstetrical and gynaecological procedures is still unknown. The disease is probably underestimated. The pathogenic mechanism involves local environment at the implant site including local inflammation and metalloproteinases activation due to local growth factors, estrogen stimulation through estrogen receptors and potential epigenetic changes. However, the underlying mechanisms are not fully explained, and we need more experimental models to understand them. The clinical presentation is heterogeneous; the patient may be seen by a gynaecologist, an endocrinologist, a general surgeon, an imaging specialist, or even an oncologist. No particular constellation of clinical risk factors has been identified, and the histological report is the major diagnostic tool for confirmation. Surgery is the first line of therapy. Further on we need protocols for multidisciplinary investigations and approaches.

Oncogenic BRAF and KRAS mutations in endosalpingiosis

Endosalpingiosis, a microscopic lesion composed of ectopic Fallopian tube epithelium, frequently involves the peritoneum and lymph nodes in patients with ovarian serous borderline tumour or low-grade serous carcinoma, but its pathogenic significance remains unclear. Using laser-capture microdissection and droplet digital PCR, we investigated whether endosalpingiosis harbours the driver mutations in BRAF and KRAS that characterise ovarian low-grade serous neoplasms. Somatic mutations were detected in 14 (33%) of 43 endosalpingiotic lesions analysed. Of 21 women with endosalpingiosis associated with a synchronous or metachronous ovarian low-grade serous tumour, mutations were identified in endosalpingiotic lesions from 11 (52%) women, with most cases (10/11, 91%) demonstrating identical mutations in both tumour and endosalpingiosis. In contrast, of 13 cases of endosalpingiosis not associated with an ovarian tumour, only one harboured a KRAS mutation. The proliferative activity as assessed by Ki-67 immunohistochemistry was lower in endosalpingiosis than in low-grade serous tumours, and endosalpingiosis with either a BRAF or KRAS mutation had a significantly lower Ki-67 index than those without. Ectopic expression of KRAS^G12V in Fallopian tube epithelial cells led to ERK phosphorylation, p21 induction, growth arrest and cellular senescence. In conclusion, we demonstrate that endosalpingiosis represents an interesting example of cancer driver mutations in deceptively normal-appearing cells, which may be prone to neoplastic transformation upon bypass of endogenous oncosuppressive mechanisms. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

The Pathogenesis of Endometriosis: Molecular and Cell Biology Insights

The etiopathogenesis of endometriosis is a multifactorial process resulting in a heterogeneous disease. Considering that endometriosis etiology and pathogenesis are still far from being fully elucidated, the current review aims to offer a comprehensive summary of the available evidence. We performed a narrative review synthesizing the findings of the English literature retrieved from computerized databases from inception to June 2019, using the Medical Subject Headings (MeSH) unique ID term "Endometriosis" (ID:D004715) with "Etiology" (ID:Q000209), "Immunology" (ID:Q000276), "Genetics" (ID:D005823) and "Epigenesis, Genetic" (ID:D044127). Endometriosis may origin from Müllerian or non-Müllerian stem cells including those from the endometrial basal layer, Müllerian remnants, bone marrow, or the peritoneum. The innate ability of endometrial stem cells to regenerate cyclically seems to play a key role, as well as the dysregulated hormonal pathways. The presence of such cells in the peritoneal cavity and what leads to the development of endometriosis is a complex process with a large number of interconnected factors, potentially both inherited and acquired. Genetic predisposition is complex and related to the combined action of several genes with limited influence. The epigenetic mechanisms control many of the processes involved in the immunologic, immunohistochemical, histological, and biological aberrations that characterize the eutopic and ectopic endometrium in affected patients. However, what triggers such alterations is not clear and may be both genetically and epigenetically inherited, or it may be acquired by the particular combination of several elements such as the persistent peritoneal menstrual reflux as well as exogenous factors. The heterogeneity of endometriosis and the different contexts in which it develops suggest that a single etiopathogenetic model is not sufficient to explain its complex pathobiology.

Different mutation profiles between epithelium and stroma in endometriosis and normal endometrium

STUDY QUESTION

Are there common mutation profiles between epithelial and stromal cells in ovarian endometriotic tissue and the normal endometrium?

SUMMARY ANSWER

Our study revealed no common mutations between epithelial and stromal cells in ovarian endometriotic tissue and the normal endometrium.

WHAT IS KNOWN ALREADY

Epithelial cells in both ovarian endometriotic tissue and the normal endometrium harbor somatic mutations in cancer-associated genes such as phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) and KRAS proto-oncogene, GTPase (KRAS).

STUDY DESIGN, SIZE, DURATION

We performed a retrospective study to identify the mutation profiles of stromal cells in endometriotic tissue and the normal endometrium. We collected 11 endometriotic stroma samples and 10 normal endometrial stroma samples between 2013 and 2017 at a tertiary care center.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The laser microdissection method was used to obtain stromal cells in ovarian endometriotic and normal endometrial tissues from patients with ovarian endometriosis and/or other non-invasive gynecological diseases. Target gene sequencing was performed to assess and compare the mutation profiles of stromal cells with those of epithelial cells obtained in our previous study. For target gene sequencing, 76 genes were selected based on previous genomic analyses for ovarian endometriosis, normal endometrium, endometriosis-related ovarian cancer and endometrial cancer.

MAIN RESULTS AND THE ROLE OF CHANCE

Stromal samples in ovarian endometrioma and normal endometrium harbor somatic mutations (18 mutations in 11 endometriosis samples and 16 mutations in 10 normal endometrial samples) but did not share any mutations with paired epithelial samples. The mutant allele frequency of stromal samples was significantly lower than that of epithelial samples in ovarian endometrioma (P = 6.0 × 10-11) and normal endometrium (P = 1.4 × 10-7).

LIMITATIONS, REASONS FOR CAUTION

The number of genes evaluated in the mutational analysis was limited. Additionally, the functional roles of somatic mutations in stromal cells remain unclear.

WIDER IMPLICATIONS OF THE FINDINGS

Different mutation profiles between paired epithelial and stromal cells in both ovarian endometrioma and normal endometrium suggest that origins of epithelial and stromal cells would be independent of each other in both normal endometrium and ovarian endometrioma; however, the theory of epithelial-mesenchymal transition is proposed in ovarian endometrioma.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported in part by the Japan Society for the Promotion of Science KAKENHI grant number JP15H02373 (Grant-in-Aid for Scientific Research A for I.I.), JP16H06267 (Grant-in-Aid for Young Scientists A for K.Y.), JP17K08688 (Grant-in-Aid for Scientific Research C for H.N.) and JP16H06279 (Grant-in-Aid for Scientific Research on Innovative Areas—Platforms for Advanced Technologies and Research Resources for H.N. and K.Y). There are no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

Not applicable.

The Origin and Pathogenesis of Endometriosis

Recent molecular genetic findings on endometriosis and normal endometrium suggest a modified model in which circulating epithelial progenitor or stem cells intended to regenerate uterine endometrium after menstruation may become overreactive and trapped outside the uterus. These trapped epithelium-committed progenitor cells form nascent glands through clonal expansion and recruit polyclonal stromal cells, leading to the establishment of deep infiltrating endometriosis. Once formed, the ectopic tissue becomes subject to immune surveillance, resulting in chronic inflammation. The inflammatory response orchestrated by nuclear factor-κB signaling is exacerbated by aberrations in the estrogen receptor-β and progesterone receptor pathways, which are also affected by local inflammation, forming a dysregulated inflammation-hormonal loop. Glandular epithelium within endometriotic tissue harbors cancer-associated mutations that are frequently detected in endometriosis-related ovarian cancers. In this review, we summarize recent advances that have illuminated the origin and pathogenesis of endometriosis and have provided new avenues for research that promise to improve the early diagnosis and management of endometriosis.

Correction: Heterogeneity of endometriosis lesions requires individualisation of diagnosis and treatment and a different approach to research and evidence based medicine

Statistical significance is used to analyse research findings and is together with biased free trials the cornerstone of evidence based medicine. However traditional statistics are based on the assumption that the population investigated is homogeneous without smaller hidden subgroups. The clinical, inflammatory, immunological, biochemical, histochemical and genetic-epigenetic heterogeneity of similar looking endometriosis lesions is a challenge for research and for diagnosis and treatment of endometriosis. The conclusions obtained by statistical testing of the entire group are not necessarily valid for subgroups. The importance is illustrated by the fact that a treatment with a beneficial effect in 80% of women but with exactly the same but opposite effect, worsening the disease in 20%, remains statistically highly significant. Since traditional statistics are unable to detect hidden subgroups, new approaches are mandatory. For diagnosis and treatment it is suggested to visualise individual data and to pay specific attention to the extremes of an analysis. For research it is important to integrate clinical, biochemical and histochemical data with molecular biological pathways and genetic-epigenetic analysis of the lesions.

Mixed endometrioid and clear cell carcinoma arising from laparoscopic trocar site endometriosis

Laparoscopic port site endometriosis is less common in abdominal wall endometriosis, and malignant transformation of abdominal wall endometriosis is rare. We reported a case of mixed endometrioid and clear cell carcinoma arising from port site endometriosis. The patient was a 49-year-old woman with a history of laparoscopic excision of ovarian endometrioma. Physical examination revealed a subcutaneous solid tumor around the laparoscopic surgical scar. Imaging showed a suspicious malignancy. She underwent radical marginal resection of the abdominal wall tumor, flap reconstruction of the abdominal wall, hysterectomy, bilateral salpingo-oophorectomy and omental biopsy. Histological examination revealed mixed endometrioid and clear cell carcinoma. Computed tomography scan showed no evidence of recurrence after six cycles of chemotherapy. This is the first case of malignant transformation from laparoscopic trocar site endometriosis.

Genes' Interactions: A Major Contributor to the Malignant Transformation of Endometriosis

The genetic and epigenetic factors that contribute to the malignant transformation of endometriosis are still under investigation. The objective of the present study was to investigate the genetic link between endometriosis and cancer by examining and correlating the latest clinical observations with biological experimental data. We collected updated evidence about the genetic relationship between endometriosis and cancers by conducting a comprehensive search of PubMed and Scopus databases, focusing on the papers published between January 2018 and January 2019. New insights into the mechanism of the malignant transformation of endometriosis have been published recently. The use of state-of-the-art techniques and methods, such as the genome-wide association study analysis and the weighted gene co-expression analysis, have significantly altered our understanding of the association between endometriosis and endometriosis-associated cancer development. Interestingly, the interactions formed between genes seem to play a pivotal role in the phenotypic expression of mutations. Therefore, the effect of single nucleotide polymorphisms and the function of the expression quantitative trait loci on genes’ expression have been the subject of many recent works. In addition, it has been discovered that genes, the mutations of which have been related to the development of endometriosis, play a role as hub genes. This may lead to new areas of research for understanding the mechanism of malignant transformation of the disease. Significant steps forward have been made towards the identification of factors that control the malignant transformation of endometriosis. Still, due to rarity of the event, a better-organized scheme for sampling on a global level should be adopted.