How is the quality of the study?

‘This study presents itself as a robust and well-founded work, based on data from the Nurses' Health Study II cohort, renowned for its rigour and comprehensiveness. The analysis spans nearly three decades, employs validated methods to collect data through biannual surveys, and uses careful diagnostic confirmations, while adequately controlling for confounding factors. The sample size and person-years of follow-up add considerable weight to the conclusions.

That said, as with all studies, it has certain limitations. Some aspects, such as possible errors in the classification of exposures and the evolution of diagnostic criteria, should be taken into account when interpreting the results. On the other hand, it is important to note that the authors belong to an internationally renowned research group, known for their significant contributions in the field of endometriosis. This undoubtedly adds credibility and quality to the analysis presented’.

How does it fit with the existing evidence and what contributions does it make?

‘The study provides relevant evidence by exploring the relationship between endometriosis, uterine fibroids and premature mortality, especially with regard to gynaecological cancer. Although these conditions were already known to be associated with an increased risk of chronic diseases, this work goes a step further by focusing on mortality.

One of the main contributions is its focus on cause-specific mortality, particularly the interaction between these conditions and cancer risks. This analysis underlines the need to consider gynaecological diseases in a broader context of comprehensive women's health. It also reinforces the importance of early and personalised management, with both clinical and health policy implications.

Another highlight of the study is the protective effect that appears to be associated with hysterectomy in women with uterine fibroids, especially in relation to the reduction of certain mortality risks. This finding underlines the need to explore further whether this protective effect is also observed in more conservative procedures such as myomectomy. Given that current trends favour less invasive surgical techniques that preserve uterine functionality when possible, it would be crucial to investigate whether myomectomy offers similar long-term benefits in terms of mortality and quality of life. This type of analysis could have important implications for optimising surgical care for patients with fibroids and for clinical decision-making based on individualised risks and benefits’.

Do you have any notable limitations?

• "Population Studied (NHSII): as with other studies based on this cohort, the majority of participants are US nurses, which limits the generalisability of the findings to more diverse populations.
• Evolution of diagnostic criteria: the study is based on laparoscopic diagnosis for endometriosis and ultrasound or hysterectomy for fibroids. However, current trends prioritise less invasive methods, such as ultrasound, to diagnose endometriosis, which may have excluded less severe cases and biased the results towards more severe forms of the disease.
• Impact of oophorectomy [removal of one or two ovaries]: rates of oophorectomy are higher in women with endometriosis and fibroids. This procedure, which is becoming less common due to the trend towards ovarian conservation, is not addressed in depth in the study. Since oophorectomy may influence the risk of cancer mortality and cardiovascular health, this omission may affect the interpretation of the findings.
• Confounding factors not considered: although the analysis adjusts for multiple variables, the influence of other factors, such as genetic predispositions or health care-seeking patterns, which could bias the results, cannot be excluded.
• Socio-economic and cultural context: the results reflect a specific health care setting, which may limit their applicability to other settings with differences in access and diagnostic practices.

What are the implications?

• "Clinical: the findings reinforce the importance of a proactive, multidisciplinary approach to the management of endometriosis and fibroids. They also suggest that these diseases should be considered in planning cancer prevention strategies.
• Research: There is a need to investigate how current diagnostic advances and more conservative surgical trends impact on long-term mortality. In addition, it would be useful to develop validated tools to assess how these diseases affect quality of life and patient empowerment.
• Policy: This work highlights the need to implement awareness campaigns that address diagnostic delays and improve equitable access to care, especially for women with gynaecological diseases.

In conclusion, this study offers a significant contribution to the understanding of the long-term effects of endometriosis and uterine fibroids on mortality. The involvement of an internationally recognised research group in the field of endometriosis adds weight and credibility to the work. However, the limitations identified, such as evolving diagnostic criteria and the impact of procedures such as oophorectomy, need to be addressed in future research to maximise the scope and practical utility of these findings in improving women's health’.