How to Read: Global Cancer Statistics 2020: GLOBOCAN Estimates of Incidence and Mortality Worldwide for 36 Cancers in 185 Countries [Reading Guide]

This guide will help you efficiently read "Global Cancer Statistics 2020: GLOBOCAN Estimates of Incidence and Mortality Worldwide for 36 Cancers in 185 Countries" using the three-pass approach.

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First pass (5–10 min)

The goal of this pass is to get a high-level overview and decide if the paper is relevant to your interests.

• What to skim:

  • Title: "Global Cancer Statistics 2020: GLOBOCAN Estimates of Incidence and Mortality Worldwide for 36 Cancers in 185 Countries" – Immediately tells you the scope (global, 2020 data), what's being estimated (incidence, mortality), and the breadth (36 cancers, 185 countries).
  • Abstract: Read this fully. It summarizes the key findings, including the most common and deadliest cancers, global burden, and future projections.
  • Introduction (first and last paragraphs): The first paragraph sets the stage for the importance of global cancer statistics. The last paragraph outlines the study's objectives.
  • Conclusion: Read the final paragraph of the "Discussion" section (page 14). This will reiterate the main takeaways and implications.

• What to notice:

  • Problem: The ongoing and increasing global cancer burden, and the need for up-to-date, comprehensive statistics to inform cancer control strategies.
  • Contributions: This paper provides the GLOBOCAN 2020 estimates, offering a detailed snapshot of cancer incidence and mortality across 36 cancer types in 185 countries, broken down by sex and geographical development status. It also projects the burden to 2040.
  • Setting: The study is global in scope, using 2020 data, and categorizes countries into "transitioned" and "transitioning" based on the Human Development Index.
  • Key Findings (from Abstract/Conclusion): Note that female breast cancer has surpassed lung cancer as the most diagnosed, but lung cancer remains the leading cause of death. Also, observe the significant disparities between transitioned and transitioning countries, and the projected substantial increase in cancer cases by 2040, particularly in transitioning regions.

Second pass (up to 1 hour)

Using SpatialRead in the Second Pass

• Use the Screenshot tool to capture figures, tables, diagrams, and formulae from the PDF and use AI for simple explanations.
• Ask: "Explain Figure X at a high level", "Compare Table 2 vs 3", or "What does the y-axis represent here?"
• Download SpatialRead →

Now, dive a bit deeper to understand the main arguments, methods, and results without getting bogged down in every detail.

• What sections/figures to focus on:

  • Introduction (full read): Understand the background, the rationale for GLOBOCAN, and the specific aims of this update.
  • Methods (skim for understanding, not replication):
    • "Data Sources" (page 3): Understand that the estimates are derived from GLOBOCAN 2020, which uses national cancer registry data and other sources.
    • "Estimation Methods" (page 3): Note the use of age-standardized rates (ASR) for comparison and the methods for projecting future burden.
    • "Geographical Groupings" (page 3): Understand the definitions of "transitioned" and "transitioning" countries, as these are central to many comparisons.
  • Results (focus on key findings and visuals):
    • Figure 1 (page 4): Quickly grasp the global distribution of cancer incidence and mortality by sex and region.
    • Figure 2 (page 5): Observe the top 10 cancers by incidence and mortality across different regions. This highlights regional variations.
    • Figure 3 (page 6): Focus on the global burden by cancer type and sex. This is crucial for understanding the overall landscape.
    • Table 1 (page 7): Compare incidence and mortality rates between transitioned and transitioning countries. This table underpins many of the paper's key arguments about disparities.
    • Table 2 (page 8): Review the global incidence and mortality for all 36 cancers by sex. This provides the detailed breakdown.
    • Table 3 (pages 9-10): Skim the top 10 cancers by country, sex, and development status. This offers more granular insights.
    • Figure 4 (page 11): Understand the projected increase in cancer cases and deaths by 2040, especially the differential growth between transitioned and transitioning countries.
  • Discussion (read for interpretation): Focus on the main points where the authors interpret their findings, discuss implications, and compare with previous GLOBOCAN estimates.

• Key terms/questions to note:

  • What is an "Age-Standardized Rate (ASR)" and why is it used?
  • How do cancer patterns (incidence vs. mortality) differ between sexes and across different levels of country development?
  • Which specific cancers show the most significant disparities or changes from previous estimates?
  • What are the primary drivers identified for the projected increase in cancer burden?

Third pass (1–5 hours)

Using SpatialRead in the Third Pass

• Highlight complex keywords, dense paragraphs, equations, or proofs and ask for a plain-English explanation that preserves notation.
• Use AI to explain the concepts in a way that is easy to understand.
• Ask for alternative phrasings or analogies to confirm understanding without changing technical meaning.
• Connect concepts with each other using AI to build a comprehensive understanding of the paper.
• Download SpatialRead →

This is your deep dive. Critically evaluate the paper, understand its nuances, and assess its implications.

• Deep reading guidance:

  • Methods: Scrutinize the methodology. Understand the limitations of the data sources (e.g., varying quality of cancer registries, methods for estimating missing data). How robust are the estimation and projection models? Consider the potential biases introduced by these methods.
  • Results: Go through each figure and table in detail. Understand the specific numbers, trends, and comparisons. Pay close attention to the text accompanying the figures and tables, as it highlights specific observations and statistical significance. For example, why is female breast cancer incidence highest in transitioned countries, but mortality rates are considerably higher in transitioning countries (as noted in the Abstract and discussed on page 12)?
  • Discussion: Critically evaluate the authors' interpretations. Do the conclusions logically follow from the results? Are there alternative explanations for the observed trends? Pay particular attention to the "Limitations" section (page 14), which is crucial for understanding the scope and generalizability of the findings. Consider the implications for global health policy and resource allocation.
  • References: Skim the references to identify foundational papers or related work if you need to delve deeper into specific methodologies or previous GLOBOCAN reports.

• Replication pointers (understanding the data generation process):

  • This paper presents the results of the GLOBOCAN 2020 estimation process, rather than providing raw data or code for direct replication of the entire database.
  • To understand how the estimates were generated, focus on the "Data Sources" and "Estimation Methods" sections (page 3). The paper references previous GLOBOCAN methodology papers (e.g., Bray et al., 2018) which would contain the detailed statistical models and approaches used for data imputation, age-standardization, and projections.
  • "Replication" in this context would involve understanding the input data (population data, cancer registry data quality) and the statistical models used to derive incidence and mortality rates, and how these were applied to project future burdens. You would need to consult the cited methodological papers to fully grasp the computational aspects.