Prognostic and Predictive Factors in Cancer

Key points

• • A prognostic factor predicts the likely outcome regardless of treatment, such as the tumour stage, while a predictive factor forecasts response to a specific therapy.
• • Stage, which measures how far a cancer has spread, is usually the single strongest guide to outcome.
• • Histological grade, which measures how abnormal the cells look, also helps forecast how aggressive a tumour will be.
• • Hormone receptors in breast cancer are predictive, because their presence forecasts a response to hormone-blocking therapy.
• • Molecular markers such as HER2 and certain gene mutations increasingly show which targeted therapies are likely to work.