Breast cancer survival

Proportion

Breast cancer survival is an important measure of how well a country's health system detects and treats breast cancer. By following people after they are diagnosed, it reflects the combined impact of early detection, timely access to effective treatment, and the quality of care they receive.

Measuring the probability of surviving up to five years after a breast cancer diagnosis, while accounting for deaths from causes other than breast cancer, provides a fair way to compare outcomes across countries and over time. This helps countries assess their progress, identify areas for improvement, and track the impact of breast cancer control efforts.

As an impact indicator, 5-year breast cancer survival reflects the effectiveness, quality, and equity of breast cancer services across the health system.

This indicator contributes to monitoring progress towards: Sustainable Development Goal (SDG) Target 3.4: reducing premature mortality from noncommunicable diseases, and the WHO Global Breast Cancer Initiative target of reducing breast cancer mortality by 2.5% per year.

Age-standardized 5-year net survival is the probability of surviving up to five years after being diagnosed with breast cancer. Net survival is the survival attributable exclusively to breast cancer and it is estimated by removing the effects of background mortality. Background mortality is the mortality due to causes other than breast cancer.

The age distribution of breast cancer patients may vary between countries and over time, and net survival varies with age. Therefore, valid comparison of all-ages survival estimates requires age standardisation to correct for these differences. The age standardised estimate is a weighted average of the age-specific estimates and is obtained using a standard set of weights.

Overall survival, breast-cancer specific survival

WHO region, World Bank income group

Population-based cancer registries, Breast cancer ICD 10-C50

To predict 5-year net survival for women diagnosed with breast cancer between 2017 and 2021 for all countries, a Bayesian hierarchical statistical model was used to combine information from population-based cancer registry estimates, covariates associated with breast cancer survival, and regional levels and trends. Where observed survival estimates were submitted by Member States during the Country Consultation, these were used as the final estimates with no modelling applied and a vetting process was carried out to ensure that country-submitted estimates adhered to consistent case definitions and to ensure there was strong alignment between observed estimates and the predicted values from the model.

Modelling and Country consultations

5-year net survival (%)

Every five years

Every five years

nyangasim@who.int

Mary Nyangasi

4689

- Limited coverage of populated -based cancer registries/ population-based data especially in LMICs

- Requires longitudinal follow-up and linkage to vital status—not always feasible in low-resource settings.

- Loss to follow-up and incomplete death registration may bias survival estimates.

- Use of limited hospital-based cancer registries data (with no adjustment).

- Modelled and uncertain covariates although uncertainty is not propagated into the survival estimates.