Explainer: Understanding Cancer Data (Staging, Treatment) for Non-Experts
Comments on a data visualization about breast cancer treatment (specifically tumor-stage changes pre- and post-chemotherapy) show that many non-specialist viewers are confused and seeking clarity. Phrases like "What do the stages T0 through T4 mean?", "For those of us not in the field...", "Some background would've been helpful for OP to include," and "Impossible to read and understand" clearly indicate a significant need for accessible explanations of medical terminology, data interpretation, and fundamental cancer concepts. Users also expressed confusion about basic principles like cancer staging ("What I’m particularly confused about is you don’t change cancer stage?").
Product Opportunity: There's a clear opportunity for an information resource series (e.g., a collection of accessible articles, infographics, short explainer videos, or a dedicated online guide) designed to help laypeople understand:
- Cancer Staging Systems: Specifically, the TNM classification (with a focus on 'T' stages T0-T4 as per the discussion), explaining what each stage signifies in simple terms and how staging is determined.
- Interpretation of Medical Data Visualizations: Guidance on how to read and understand common chart types used to present medical data, such as Sankey diagrams (the type used in the original post), including what different elements (e.g., node size, flow width, color changes) represent in the context of treatment outcomes.
- Basic Concepts of Cancer Treatment and Response: Explanations of terms like "pre-surgery chemotherapy," "tumor regression" (e.g., from T2 to T1), what these changes mean for a patient, and addressing common questions like the implications for surgery or whether cancer stages can "change."
Expected Benefits:
- Improved Health Literacy: Patients, their families, and the general public will be better equipped to understand complex medical information regarding cancer diagnosis and treatment.
- Enhanced Patient-Doctor Communication: Individuals with a foundational understanding can have more productive and informed conversations with healthcare providers, leading to better shared decision-making.
- Empowerment Through Knowledge: Demystifying complex medical concepts can reduce anxiety and empower individuals to take a more active role in their health or the care of loved ones.
- More Accurate Interpretation of Public Health Data: Enables a wider audience to correctly understand medical research findings and health statistics presented in visual formats.
- Reduced Misinformation and Confusion: Clear, accessible explanations can help prevent misinterpretations of complex medical data and concepts.
Origin Reddit Post
r/dataisbeautiful
[OC] Primary tumor-stage (breast cancer), before and after pre-surgery chemotherapy (n=1599).
Posted by u/Flavivi•06/01/2025
Top Comments
u/Alert-One-Two
What I’m particularly confused about is you don’t change cancer stage? https://my.clevelandclinic.org/health/diagnostics/22607-cancer-stages-grades-system
u/Alert-One-Two
What I’m particularly confused about is you don’t change cancer stage? https://my.clevelandclinic.org/health/diagnostics/22607-cancer-stages-grades-system
u/Bynming
I'd like to see it with the "stage" boxes color-coded to match on both sides
u/cool_hand_legolas
i guess this is good for total cases but given how many people are T2 to start it makes me wonder (1) selection bias, if T2 are suggested most for this treatment and (2) success as a proporti
u/campbell363
Some background would've been helpful for OP to include.
The T likely refers to the TNM staging classification system. For various cancers, the TNM classification will help with risk strati
u/Quasi-Free-Thinker
I’d keep the stages on the same level on both sides so it’s clearer when it’s going up, down , or even. That way you don’t have T2 -> T2 look like an increase, for example
u/xthecharacter
It still implies that every T4 regresses after pre-surgery chemo, which I have my doubts about
u/xthecharacter
It still implies that every T4 regresses after pre-surgery chemo, which I have my doubts about
u/campbell363
Does the relative height of each stage represent the number? So, pre-chemo T1 has relatively fewer cases compared to post-chemo T1?
u/re_carn
What does stage T0 on the left mean?
u/NuffMusic
This is not beautiful. This is giving me a headache.
u/grudginglyadmitted
problem is, the biggest section by far at baseline is the T2, and the biggest after is T1; you’d have to space everything out a lot more in order to have everything line up
u/re_carn
What does stage T0 on the left mean?
u/GoldenFalls
I think the problem is there's no T4 on the post-treatment side. This also means baseline T3 cannot be shown to progress since there's no T4 option for them to progress to post-treatment.
u/Sibula97
Not that fast I guess. Note that this is the preoperative chemotherapy, so basically a window of just a few weeks. Then there's surgery and whatever happens afterwards. Eventually all of them
u/2knee1
This is a good graphic, a suggestion would be to use different colors for different stages and to make them either darker for worsening cancer and lighter for improvement
u/2knee1
This is a good graphic, a suggestion would be to use different colors for different stages and to make them either darker for worsening cancer and lighter for improvement
u/campbell363
Some background would've been helpful for OP to include.
The T likely refers to the TNM staging classification system. For various cancers, the TNM classification will help with risk strati
u/grudginglyadmitted
problem is, the biggest section by far at baseline is the T2, and the biggest after is T1; you’d have to space everything out a lot more in order to have everything line up
u/DaiLoDong
The colors do their job well. It's quite a good representation of the data
u/TestingTehWaters
Impossible to read and understand
u/campbell363
I wonder if the tumor size is large enough, would they skip chemo and go straight to surgery? In this case, that portion of the T4 population wouldn't be included in these data.
Alternativel
u/acanthocephalic
I once modified a python Sankey library to allow color gradients for transitions between categories , it looked cool
u/acanthocephalic
I once modified a python Sankey library to allow color gradients for transitions between categories , it looked cool
u/Flavivi
Where or how you got the data: Regional Cancer Centres in Sweden.
The tool used to generate the visual: R Script (alluvial package).
u/campbell363
This data doesn't show metastatic tumors. The T, if they're using the TNM classification, characterizes the primary tumor involvement of the breast. The N & M describe the metastasis comp
u/Quasi-Free-Thinker
I’d keep the stages on the same level on both sides so it’s clearer when it’s going up, down , or even. That way you don’t have T2 -> T2 look like an increase, for example
u/NuffMusic
This is not beautiful. This is giving me a headache.
u/TestingTehWaters
Impossible to read and understand
u/Oulley
I agree. It's honestly pretty bad. Some of the grey bands that mean change are visually going up. No color coding on stages and the heights of the stages aren't the same pre and post.
u/rejeremiad
Don't any of the cases die? Every T4 regresses?
u/nerfcarolina
Sankey diagram
u/Sibula97
Not that fast I guess. Note that this is the preoperative chemotherapy, so basically a window of just a few weeks. Then there's surgery and whatever happens afterwards. Eventually all of them
u/campbell363
You won't be restaged from your original diagnosis but there are various points when cancer will be reevaluated. This reevaluation is necessary to determine treatment/next steps.
The T in O
u/Nillavuh
What do the stages T0 through T4 mean? How positive of a development is it if cancer regresses from T2 to T1? Does that negate the need for surgery? What drives the need for surgery?
For tho
u/MrNiceguy037
I have been trying to use alluvial but it does not look nearly as nice! Would you care to send me a code snippet in a dm?
u/DaiLoDong
The colors do their job well. It's quite a good representation of the data
u/DevelopmentSad4798
Same question - why is there no T4 on the right side?
u/Bynming
I'd like to see it with the "stage" boxes color-coded to match on both sides
u/thentangler
What is the name for this kind of chart again?
u/Jonny36
Id agree, that means every case that had metathesized to other tissues, had all growth in other tissues completely removed by chemotherapy alone? Considering stage 4 cancer is usually seen as
u/MrNiceguy037
I have been trying to use alluvial but it does not look nearly as nice! Would you care to send me a code snippet in a dm?
u/campbell363
I wonder if the tumor size is large enough, would they skip chemo and go straight to surgery? In this case, that portion of the T4 population wouldn't be included in these data.
Alternativel
u/Flavivi
Where or how you got the data: Regional Cancer Centres in Sweden.
The tool used to generate the visual: R Script (alluvial package).
u/Quasi-Free-Thinker
True, but I think the space would enhance the message: T2 cases are where most treatments start, and they mostly step down due to effective treatment.
Compressing the chart takes away from
u/Oulley
I agree. It's honestly pretty bad. Some of the grey bands that mean change are visually going up. No color coding on stages and the heights of the stages aren't the same pre and post.
u/Nillavuh
What do the stages T0 through T4 mean? How positive of a development is it if cancer regresses from T2 to T1? Does that negate the need for surgery? What drives the need for surgery?
For tho
u/Jonny36
Id agree, that means every case that had metathesized to other tissues, had all growth in other tissues completely removed by chemotherapy alone? Considering stage 4 cancer is usually seen as
u/rejeremiad
Don't any of the cases die? Every T4 regresses?