Prognosis and survival for thymus cancer

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A prognosis is the doctor’s best estimate of how cancer will affect you and how it will respond to treatment. Survival is the percentage of people with a disease who are alive at some point in time after their diagnosis. Prognosis and survival depend on many factors.

Your doctor will look at certain aspects of the cancer as well as characteristics such as your age and if you have any other health problems. These are called prognostic factors. Your doctor will also look at predictive factors, which influence how a cancer will respond to a certain treatment and how likely it is that the cancer will come back after treatment.

Prognostic and predictive factors are often discussed together. They both play a part in deciding on a prognosis and a treatment plan just for you. Only a doctor familiar with your medical history, the type and stage or other features of the cancer, the treatments chosen and the response to treatment can put all of this information together with survival statistics to arrive at a prognosis and chances of survival.

The following are prognostic and predictive factors for thymus cancer.

Classification

Most thymus cancers are divided into groups using the World Health Organization (WHO) classification system. Type A, type AB and type B1 thymomas usually have a very good prognosis because the tumour cells look like normal thymus cells. Type B2 and type B3 thymomas have a less favourable prognosis because they are made up of abnormal thymus cells.

Thymic carcinomas (also called type C) usually have a poorer prognosis than thymoma because they tend to be aggressive tumours that have grown quickly and spread to other parts of the body when they are diagnosed. These cancer cells look very different from normal epithelial cells of the thymus.

Find out more about the classification of thymoma and thymic carcinoma.

Stage

Stage is an important prognostic factor for thymus cancer. Early-stage thymoma or thymic carcinoma that is only in the thymus or surrounding fat tissue has a better prognosis than later- stage cancers that have grown into nearby organs or tissues in the chest or spread to other areas of the body.

Find out more about stages of thymus cancer.

Surgery to remove the tumour

Surgery is usually used to treat thymus cancer. Thymus cancer that is completely removed by surgery has a much more favourable prognosis than thymus cancer that is not completely removed or if surgery can’t be done.

Age

People who are older than 70 have a less favourable prognosis than people younger than 70.

Survival statistics for thymus cancer

Survival statistics for cancer are very general estimates and must be interpreted very carefully. Because these statistics are based on the experiences of groups of people, they cannot be used to predict a particular person’s chances of survival.

There are many different ways to measure and report cancer survival statistics. Your doctor can explain these statistics and what they mean to you.

Net survival

Net survival represents the probability (chance) of surviving cancer in the absence of other causes of death. It is used to give an estimate of the percentage of people who will survive cancer.

In Canada, thymus cancer is grouped and reported together with similar cancers in a category called “other endocrine cancers.” The estimated 5-year net survival statistic of 63% does not necessarily reflect the actual survival for the individual cancers within the group. What it means is that about 63% of people diagnosed with these endocrine cancers will survive for at least 5 years.

Survival by stage and type

Survival varies with each stage and type of thymus cancer according to the World Health Organization (WHO) classification system. Generally, thymoma has a better survival than thymic carcinoma. Often thymic carcinoma grows quickly and is not found until it is at an advanced stage, which can make it more difficult to treat.

There are no specific Canadian statistics available for the different stages and types of thymus cancer. The following information on observed survival comes from a variety of sources. It includes statistics from other countries that are likely to have similar outcomes as in Canada.

Thymoma survival

TNM stage

5-year observed survival

1

96%

2

89.3%

3A

89%

3B

71%

4A 83%
4B 79%
Thymic carcinoma survival
TNM stage 5-year observed survival
1 80-88%
2 69%
3A 57%
3B 56%
4A 54%
4B 33%

Questions about survival

Talk to your doctor about your prognosis. A prognosis depends on many factors, including:

  • your health history
  • the type of cancer and the types of cells that make up the tumour
  • the stage
  • the treatments chosen
  • how the cancer responds to treatment

Only a doctor familiar with these factors can put all of this information together with survival statistics to arrive at a prognosis.

Expert review and references

  • Donna Maziak, MD, MSc, FRCPC
  • Girard N, Ruffini E, Marx A, Faivre-Finn C, Peters S. Thymic epithelial tumours: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up. Annals of Oncology. 2015: Supplement 5:v40-v55.
  • Cabezon-Gutierrez L, Pacheco-Barcia V, Carrasco-Valero F, Palka-Kotlowska M, Custodio-Cabello S, Khosravi-Shahi P. Update on thymic epithelial tumors: a narrative review. Mediastinum. 2024: 8:33.
  • PDQ Adult Treatment Editorial Board. Thymoma and Thymic Carcinoma Treatment (PDQ®) – Health Professional Version. Bethesda, MD: National Cancer Institute; 2024. https://www.cancer.gov/.
  • Sorin V, Kirshenboim Z, Klug M, Ahuja J, Marom EM. The ninth edition TNM staging classification for thymic epithelial tumors. Seminars in Ultrasound CT and MRI. 2024: 45: 420-429.

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