Rare gynaecological cancers in Malta - An analysis of incidence between 2010 and 2021.

Abstract

Introduction: Whilst about 18 % of all cancers in females are gynaecological cancers, more than 50 % of these can be classified as rare tumours (defined as an annual incidence of <6 per 100,000). Such cancers represent an important challenge for small countries like Malta where the small caseload may limit the expertise of clinicians in the diagnosis and treatment of such cancers.

Methodology: The study uses data from the Maltese population-based cancer registry to examine trends in incidence rate of the rare gynaecological cancers for the 12-year period between 2010 and 2021. It employs the RARECAREnet list to identify the rare gynaecological cancers by major rare gynaecological cancer categories and histological types and analyses the number of cases and incidence rates in Malta to monitor trends and provide an insight of the burden of such cancers.

Results: A total of 709 new cases of rare gynaecological cancers were discovered during the 12-year period. Globally, these rare gynae cancers, constituted 42.6 % of all the gynae cancers that occurred during this period. Most of these rare cancers were ovarian (399 cases, 56.3 %), followed by rare cancers of the vulva and vagina (122 cases, 17.21 %), rare cancers of the corpus uteri (93 cases, 13.12 %) and rare cancers of the cervix uteri (73 cases, 10.3 %). Other rare gynaecological cancers (10 cases, 1.41 %) and cancers of the placenta (2 cases, 0.04 %) were much rarer. The outcomes in terms of 5-year survival was worse for the rare cancers compared with the commoner types of gynae cancers with an overall 5-year survival of 45.10 % and 45.48 % for rare gynae cancers for the 2010-2014 and 2015-2019 cohorts respectively and an overall 5-year survival of 69.94 % and 73.44 % for the common gynae cancers for the 2010-2014 and 2015-2019 cohorts respectively.

Conclusion: The study shows that globally rare gynaecological cancers in a small state like Malta are in fact not so rare - with a total of 709 rare gynaecological cancers in 12 years for Malta. These cases are however few when considering that they are divided into over 30 different histopathological groups. Numbers are also small when it comes to accumulating statistical power for analysis. The caseload for the individual sub-categories is small and will often be shared amongst the different individual gynaecologists and/or their clinical team. Thus, it might be difficult for these specialists to gather enough technical expertise that is crucial for early diagnosis and the treatment of these rare cancers. This study provides a rationale for international collaboration where there is scope for joint research and sharing of expertise. Establishment of common databases for the various types of rare gynaecological tumours will provide statistical power, enabling analysis of outcomes for these rare cancers and establishment of guidelines.