New link between endometriosis and ovarian cancer

International researchers have found a possible link between endometriosis and higher risk of ovarian cancer, but they say that risk changes dramatically depending on the type of endometriosis.
 
The population-based cohort study used data from the Utah Population Database and noted that ovarian cancer risk was markedly increased among women with ovarian endometriomas or deep infiltrating endometriosis.
 
The research ultimately followed 500,000 women over 20 years, concluding that endometriosis ‘seems to affect the risk and cancer type’, with a strong link between deep infiltrating endometriosis and type I ovarian cancer.
 
But author Dr Karen Schliep said given the rarity of ovarian cancer, the excess risk was relatively small, with 10–20 additional cases per 100,000 women.
 
‘Nevertheless, women with endometriosis, notably the more severe subtypes, may be an important population for targeted cancer screening and prevention studies,’ she said.
 
The research found that women with endometriosis had a 4.2-fold higher ovarian cancer risk than those without the condition.
 
Women with ovarian endometriomas and/or deep infiltrating endometriosis had a 9.7-fold higher risk compared to those without.
 
But GP and women’s health expert Associate Professor Magda Simonis questioned the research, telling newsGP most women with endometriosis will never suffer from cancer related to this ‘as it is a benign disease’.
 
‘For those suffering from endometriosis, it is important to note that the lifetime risk for developing ovarian cancer is low with approximately 1.9%, as compared to 1.4% for the general population, since ovarian cancer is not frequent when compared to other cancers,’ she said.
 
‘There is longstanding evidence which suggests that certain epithelial ovarian cancer subtypes, specifically ovarian clear cell and endometrioid ovarian carcinoma are directly related to endometriosis, however.’
 
Associate Professor Simonis said these cancer subtypes occur ‘with types of deep infiltrating endometriosis, which is the severe form of extensive disease that affects the ovaries too’.
 
She said previous research has described this connection as far back as 1925, as an endometriosis-associated ovarian endometrioid carcinoma.
 
Dr Schliep said the results show that women with endometriosis, especially the more severe subtypes, should receive targeted cancer screening and prevention strategies to catch these cancers early.
 
‘Precision medicine is more than just genetics,’ she said.
 
‘Clinical features, including a woman’s history of endometriosis and type of endometriosis, may inform ovarian cancer risk prediction models.’
 
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