Cancer risk Evaluation in Korean Endometriosis Cohort

Endometriosis and the cancer risk

Key Points

Highlights:

• There is an increase in the prevalence of ovarian, uterine, cervical, breast, and thyroid cancer risk in women with endometriosis.

Importance:

• The authors conducted a nationwide, population-based long-term analysis of women with endometriosis to define all types of diagnosed cancers, and compared the results with the non-endometriosis control group from the same population.

What's done here:

• The authors analyzed the data from the Korean National Health system for patients who have ICD codes of endometriosis (2010-2013) who subsequently had another code entrance for any type of cancer diagnosis until 2018.
• The control group was selected from women of similar age who had laparotomies for appendectomy and do not have endometriosis diagnosis.
• The ICD codes for all types of cancers were checked.
• Overall cancer risks and organ-specific cancer risks in both endometriosis and control groups were analyzed including a subgroup analysis according to patient age.
• Comorbidities as hyperlipidemia, hypertension, diabetes, heart failure, chronic obstructive pulmonary disease, chronic liver cirrhosis, and kidney disease were defined as confounding variables to be used in multivariate regression analysis. 

Key Results:

• A total of 179,865 patients with endometriosis and 87,408 controls were included
• The total cancer rate was statistically higher in the endometriosis group (543.8 versus 644.3/100,000 in control and endometriosis group, hazard ratio [HR], 1.34)
• The subgroup analysis according to age showed an increased risk in all age groups in women with endometriosis.
• A statistically significant increased cancer risk was detected in uterus, followed by the ovary, cervix, breast, and thyroid.
• The median age for the first time diagnosis of any type of cancer in women with endometriosis was earlier than 50 years of age.

Limitations:

• The study reflects the genetic pool of Korea and also the confounding factors such as parity, menopausal status, medications, previous hysterectomy, and lifestyle choices that may affect the cancer risk were not measured which hardens to make an assumption for all women.

Lay Summary

The relationship between endometriosis and cancer has always been challenging. The previous studies revealed an increased risk in endometriosis-associated ovarian cancers regarding the alterations in cancerogenic genes or by the effect of iron and hem coming with retrograde menstruation and causing oxidative stress in the peritoneum.

The study conducted by Kyung Jin Eoh analyzing the Korean population revealed as the overall cancer rate is increased in women with endometriosis, even at younger ages.

The authors showed not only ovarian, uterine, cervical cancer risks are increased, but also the organs far away from endometriotic lesions and menstrual blood such as breast and thyroid also have increased cancer rates.

The reason for this was hypothesized to be as the result of an altered immune system and increased inflammation in women with endometriosis.

Even the study was nationwide and drawn from a reliable health system database, it still has its limitations including only covering the Korean nation and not including confounding factors such as hormonal treatment use, previous hysterectomies, or lifestyle statuses such as smoking or alcohol use.

The authors pointed out the most imperative finding of this study as the importance of warning women with endometriosis to have regular cancer checks starting in ages earlier than 50.

This interesting article was recently published in "Gynecologic Oncology".

Research Source: https://pubmed.ncbi.nlm.nih.gov/33514482/