Cancer arising from adenomyosis is very rare, with transformation occurring in only 1% of cases and in older individuals. Adenomyosis, endometriosis and cancers may share a common pathogenic mechanism that includes hormonal factors, genetic predisposition, growth factors, inflammation, immune system dysregulation, environmental factors and oxidative stress. Endometriosis and adenomyosis both exhibit malignant behaviour. The most common risk factor for malignant transformation is prolonged exposure to oestrogens. The golden standard for diagnosis is histopathology. Colman and Rosenthal emphasised the most important characteristics in adenomyosis-associated cancer.
1. Introduction
Adenomyosis is a common, benign gynaecological disease characterised by the extension of endometrial tissue into the myometrium
[1]. It affects mostly women of late reproductive age, including women in menopause
[2,3][2][3]. Pelvic endometriosis is a common disease affecting 7–15% of women of reproductive age
[4,5][4][5], and it is expected to disappear with advancing age as it is oestrogen-dependent
[6]. However, it has a prevalence of 2–4% in postmenopausal women, and in these cases, it can be associated with adenomyosis with a rare possibility of malignancy
[6].
Adenomyosis is characterised by the presence of aberrant endometrial tissue outside of the uterine cavity in intra- and extra-abdominal sites
[4,5,7][4][5][7]. It can also occur in the cervix, round ligament, abdominal scars
[4[4][7],
7], pararectal space, paraovarian region, parametrium, liver, appendix and mesentery
[8]. It is often associated with endometriosis
[7].
Cancer arising from adenomyosis is very rare, with transformation occurring in only 1% of cases
[4,5,9][4][5][9] and in older individuals
[10]. The first case of clear cell and endometrioid carcinoma arising from adenomyosis was described in 1897
[3]. Adenomyosis is more commonly associated with endometrioid carcinoma, but clear cell carcinoma is also observed
[3,4][3][4]. Certain cell types are involved, such as epithelial and mullerian types, with sarcomas described as well
[11,12][11][12].
Even if endometriosis, adenomyosis and cancers have common manifestations, the pathogenic mechanism of malignant transformation remains unknown. A better knowledge of pathogenesis aids in diagnostic and therapeutic management
[11,12][11][12]. The histological description is important for standardising the description of cancers developed from adenomyosis and to differentiate them from those that appear simultaneously with adenomyosis without knowing the exact relationship between them
[13,14][13][14]. These concomitants are important because they modify the therapeutic strategy
[14].
As cancer arising from adenomyosis is very rare, adenomyosis, endometriosis and cancers may share a common pathogenic pathway, though the pathogenic mechanism still remains to be established. There is also a need to have a standardised treatment.
2. Pathogenesis
The pathogenesis of a malignant transformation in adenomyosis appears to involve inflammation and elevated levels of IL1 and IL6
[4]. The underlying mechanisms may involve genetic mutations, epigenetic changes, and tumour suppressor gene alterations in adenomyosis
[11]. IL-37 is also involved in adenomyosis. IL-37 was discovered through a bioinformatics analysis in 2000 and is a member of the IL-1 family. Oestrogen and progesterone do not have an effect on the IL-37 protein in cancer cells. While IL-37 does not affect the proliferation and colonisation of cancer cells, it suppresses the migration and invasion ability of endometrial cancer cells. Furthermore, a decreased expression of MMP2 via the Rac/NF-kB signalling pathway in cancers is also observed
[12].
Adenomyosis, endometriosis and cancers may share a common pathogenic mechanism that includes hormonal factors, genetic predisposition, growth factors, inflammation, immune system dysregulation, environmental factors and oxidative stress
[11] (
Table 1). Endometriosis and adenomyosis both exhibit malignant behaviour
[4,5,11,12][4][5][11][12].
Table 1.
Common pathogenic mechanisms between adenomyosis, endometriosis and cancers.