Imagine having access to a database of carefully curated, peer-reviewed tumor pathology images from all round the world. Now imagine that access is publicly available, completely free, and you don’t even need to register your details!
Now, leaving imagination aside, go visit the World Tumor Registry (WTR).
But first, let’s hear the story behind this invaluable initiative from some of the volunteers behind the scenes: Yuri Nikiforov, WTR’s Founder and President, and Chair of the Thyroid Tumors Registry; Alyaksandr (Sasha) Nikitski, Administrative Director; and Edi Brogi, Chair of the Breast Cancer Registry.
What is the WTR?
Yuri Nikiforov: The WTR is an open access educational and practical resource for pathologists, oncologists, cancer scientists, and patients. Its goal is to promote better understanding of tumor morphology and pathology.
It serves as a virtual encyclopedia of human tumor pathology. However, in contrast to platforms like Wikipedia, where anyone can add content, our posts are heavily curated by expert pathologists.
But the WTR is more than just a training resource – the overarching goals are to contribute to more effective diagnosis and treatment of cancers, and ultimately to achieve better outcomes for patients. To that end, the next development we are working on is including possible treatment options for the cases we post.
When was it established, and why?
YN: I thought about creating a tumor registry for some time, but this concept became a reality in the form of a non-profit organization established in August 2021. I wanted to leverage the opportunities offered by the recent advancements in digital pathology to create an easily and freely accessible repository of cancer cases from all over the world. The idea was to provide the most advanced – and truly global – educational resource for pathologists, physicians, and cancer scientists. It needed to foster learning, advance diagnostic precision, and bring people together rather than divide and separate them.
Many institutions and companies already have collections of digital slides of tumors, but they tend to be institution- or country-specific, with over-representation of some countries over others. Access to these resources also tends to be limited. We very rarely get to see what tumors look like in different parts of the world.
Of course, there are textbooks and articles that teach us how to diagnose tumors, but, once again, the majority seem to be written in Europe, North America, and a handful of other countries. And that leaves us with an important and yet unanswered question: does cancer look the same in different parts of the world, or are there regional differences?
This is an important question for me personally. I was trained in Belarus in Eastern Europe. In 1986, the Chernobyl nuclear disaster in Ukraine caused the spread of radioactive isotopes to Belarus and led to a rise in thyroid cancers. However, subtle differences were apparent in radiation-induced cancers compared with those that predated the Chernobyl incident.
Considering the impact of local factors on the nature of cancer, should pathologists practicing in, say, Nigeria or Peru, be learning about cancer diagnosis from samples taken in the US? How can we sort out their commonalities and differences if we don’t have any access or knowledge of local tumors?
And what about rare cancer types? In my practice, I’ve only come across two or three cases of primary angiosarcomas of the thyroid. This is such a rare cancer that, even in the USA, smaller institutions may not have any such cases on file. Accordingly, training examples for rare cancers are in short supply. Yet, in creating a global collection of cases, we already have eight thyroid angiosarcoma cases in our register that anyone can review as a training resource.
How do you source and select the images?
Sasha Nikitski: Any medical professional can contribute a case via our website. We require whole-slide images, along with case details such as patient location, demographics, and clinical information and, when available, immunohistochemical and genetic data – all in a strictly deidentified form. The contributor has the option to have their name associated with the case or remain anonymous.
YN: The WTR will initially contain three collections, by tumor type. Currently we are curating the Thyroid Cancer Registry. We are also putting together the infrastructure for the Breast Cancer Registry, which Edi will talk about. The third collection will be lung cancer.
Eventually, when the WTR is built to its full intended capacity, it will include collections for all organ systems. We expect each collection to have at least 3000 cases, with equal representation across the different world regions: Africa and Middle East, Asia and Oceania, Central and South America, Europe and North Asia, and Northern America.
To ensure diagnostic precision, the WTR is meticulously curated by experts in each field, so that the diagnosis of every case posted in the WTR has been confirmed by one of its expert editors. This is also a major distinguishing feature of the WTR compared to other available digital slides repositories.
Each Editorial Board is made up of four representatives from each of the five regions, plus a chairperson. Members submit their own cases and invite submissions from contributors in their regions.
Edi Brogi: We are actively working to identify and appoint local editors in every region, all of whom have extensive expertise in breast pathology and access to digital scanners. If a potential contributor has an interesting case but no access to slide scanning technology, they have the option to contact the local WTR editor and have the case digitized and included in the WTR on their behalf. This process is intended to resolve potential obstacles to contributing cases, so that everyone can contribute to the success of the WTR.
What’s involved with setting up the Breast Cancer Registry at the WTR?
EB: First of all I want to acknowledge all that the Thyroid Cancer Registry has achieved so far, especially considering tumors of the thyroid are not the most common types of tumor. I remember meeting Yuri and Sasha at USCAP 2024, when they presented the WTR concept to the pathology world in a public forum. I’m very impressed that, in just one year, the Thyroid Cancer Registry has already accrued more than 1000 fully annotated cases, with another 300 to 400 cases scheduled for review.
For the Breast Cancer Registry, I’m at the point of establishing contact with experts across the five world regions. This requires some time and effort, as we want to recruit the right experts who are also willing to contribute actively.
Currently, I’m also an editor of the World Health Organization classification of breast tumors, sixth edition. Once finalized, it will inform the classification of tumors for the WTR Breast Tumor Registry.
Only once all this preparatory work has been completed will we start inviting cases. As a pathologist, I know that the diagnosis is what matters most, so it's really important that we have the right reviewers and the right guidelines to ensure each diagnosis is correct.
How is the WTR funded?
YN: Funding of the WTR is definitely a challenge that occupies a lot of my time. We were fortunate to have several founding sponsors – mostly local institutions and foundations here in Pittsburgh, and a few commercial companies who knew my previous work – that got the venture off the ground. All our sponsors are listed on the WTR website, and we are grateful to them for their invaluable support.
But the WTR is a non-profit organization and we need additional sponsors and patrons in order to accelerate the development of our registries for all cancer types. Fortunately, we have a product to show to potential supporters that demonstrates what we can do to advance knowledge, diagnosis, and treatment of cancer. It is starting to gain traction with the pharmaceutical industry, and hopefully with academic institutions.
So, the fundraising continues – and that’s important because we want the WTR to grow quickly and to remain open access and free to use. At present, we are fully funded by donations; we have not had to rely on commercial avenues such as advertising revenue – although this might become necessary at some point in the future, if no other support is available.
We’re also planning some industry-sponsored educational seminars to help generate funds and offer naming rights to the organizations and individual donors for specific cancer site registries. But I want to stress that WTR will not use submitted whole slide images for any commercial purposes. All digital pathology images are securely stored and protected against unauthorized access or use by third-party companies through available technical measures..
It’s also important to note that all our editors and contributors work as volunteers, contributing their time and expertise for no benefits other than an acknowledgment against a particular case.
How do you measure and monitor audience growth on the website?
SN: The WTR website and platform were launched in March 2024, and recently we have adopted a Google Analytics tool that allows us to track website use in real time. From that, we have established that we do have a global audience – I can see we have users in Chile and Indonesia even as we speak.
We do plan to expand our analytics to collect much more audience data; but, for now, we tend to assess the reach of the WTR based on informal feedback and individual interactions.
What feedback has the WTR received from users so far?
SN: The feedback has been very positive! First of all, everyone comments on how great it is to have this as a free resource, which does not even require registration. WTR users also comment on the exceptional quality of the cases, which is something we really strive for. Our goal is to include the highest quality digital slides with the best possible case descriptions, thanks to our Editors and contributors.
Some pathologists tell us they value the opportunity to share their private collections, and the knowledge they have acquired over many years. And the users appreciate the ability to search the WTR by geographic region.
Another comment we’ve heard is that many users see the WTR as a future collaboration resource, which could potentially be used to discover and characterize new tumor diagnostic entities.
YN: Feedback has taught us that some of our users and contributors are patients. One patient, who is also a pathologist, wanted to contribute images of her own tumor as a way of giving back to the medical community.
I should stress that all our cases are deidentified. We take data protection very seriously. For instance, we can include the country and region, but not the city or more precise location of the patient or medical center. But, importantly, users can search and learn from cancer cases that occurred in their region or country, and further filter cases by age, sex, environmental factors, and so on.
How do you approach marketing for this resource?
SN: That’s a major challenge for a non-profit platform as new as the WTR, with limited budget for marketing. We do attend events to do some promotion. Most recently, the WTR team hosted a highly productive exhibition at USCAP 2025. The main comment we heard was, “Wow. This is such an excellent resource for education, training, and research. How come we never heard of it before?!”
But, because our resources for marketing are very limited, we’re reliant on media like The Pathologist to help us spread the word. And, of course, we use social media to help attract new users.
YN: I would like to use this opportunity to talk about our new offerings. Over the last two years, we have established a close partnership with Path Presenter – in fact we use their platform to host our images. With their technical support and assistance for world pathologist outreach, we plan to run a global course on thyroid cancer in November 2025. Experts from all over the world will discuss how to diagnose and treat thyroid cancer, including unknown case sessions based on the WTR cases.
We hope this event will help to elevate knowledge and diagnostic skills for pathologists who sign out thyroid samples – and raise awareness of the WTR, attracting new contributors and sponsors.
How can readers of The Pathologist get involved?
SN: Please visit https://www.worldtumorregistry.org/. We are recruiting editors for the WTR Breast Cancer Registry, and the contact details for applications can be found on the WTR home page.
If you have an unusual thyroid tumor case or practice in a country that is under-represented in the Thyroid Cancer Registry, please consider becoming a contributor. You can contact your local editor via the interactive world map on the WTR Thyroid webpage.
YN: The website is very intuitive and easy to use. At the Thyroid page, you can browse published cases, search tumors by microscopic features using our innovative tool, or contact the editor to become a WTR contributor. And keep in mind that if your case is accepted, and you agree to it, your name will be published with the case acknowledging your contribution. And, of course, there is an option on the website to donate money to help us keep this educational and diagnostic resource free for all.
Please also look out for us on social media. Our social posts provide updates on WTR activities and will soon launch a series of interesting tumor cases with links to digital slides..
We particularly encourage pathologists from underrepresented countries to become part of the World Tumor Registry and contribute their cases to this global open access bank of knowledge.
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