# Masaoka staging: follow-up study of thymomas with special reference to their clinical stages

Source: https://onco.cc/key-papers/paper-masaoka-thymoma-clinical-staging-cancer-1981/  
OnCo record `paper-masaoka-thymoma-clinical-staging-cancer-1981` (Key paper). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

The Osaka series that grouped thymomas by how far they had invaded, from fully encapsulated to spread inside the chest or beyond, and showed survival fell with each step. Its stages are still used forty years on.

## Summary

Retrospective study of 96 patients with thymoma treated at Osaka University, proposing a four-stage system: stage I encapsulated, stage II invasion into the capsule or surrounding fat, stage III invasion of neighbouring organs, stage IVa pleural or pericardial dissemination and stage IVb lymphatic or haematogenous metastasis.

Five-year survival fell with stage, validating the system, which was later refined by Koga and remained the reference until the TNM classification of 2017 and is still reported alongside it.

## Fields

- Kind: Key paper
- Last checked: 2026-09-18
- Journal: Cancer
- Year: 1981
- DOI: 10.1002/1097-0142(19811201)48:11<2485::AID-CNCR2820481123>3.0.CO;2-R
- Authors: Masaoka A, Monden Y, Nakahara K, Tanioka T.
- Findings: Survival fell progressively from encapsulated stage I thymoma to disseminated stage IV disease.
- What it means: Whether a thymoma is called stage I or stage III, and hence whether radiotherapy follows surgery, still traces back to this scheme.
- Caveats: A single-institution series of 96 patients.; Now used alongside the IASLC/ITMIG TNM classification.

## Sources

- Cancer 1981: https://doi.org/10.1002/1097-0142(19811201)48:11<2485::AID-CNCR2820481123>3.0.CO;2-R
- PubMed: https://pubmed.ncbi.nlm.nih.gov/7296496/

## Connected records

- cancers: [Thymoma (WHO types A, AB, B1, B2 and B3)](https://onco.cc/cancers/thymoma/)
- journals: [Cancer](https://onco.cc/journals/cancer-wiley/)

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