IMMUNOHISTOCHEMISTRY; P40

What this test checks

Detects p40 protein, a highly specific marker for squamous cell differentiation in tumours. More specific than p63 for squamous cell carcinomas — particularly useful for classifying lung cancers.

Why do people get this test?

Accurately distinguishing squamous cell lung cancer from adenocarcinoma is critical — they have different driver mutations and respond to different targeted therapies. P40 provides this distinction reliably.

When you should consider this test

• When classifying lung cancer as squamous vs. adenocarcinoma
• When confirming squamous differentiation in head and neck tumours
• As part of lung cancer subtyping for treatment selection

How to prepare

No preparation needed — performed on biopsy or surgical tissue.