The terms are often used together, but they describe slightly different things. Spalling describes concrete breaking, flaking or detaching. Concrete cancer usually refers to the broader deterioration process, often involving reinforcement corrosion.
Spalling is a symptom
Concrete can spall for several reasons. Reinforcement corrosion is a common cause in reinforced concrete, but impact, fire, freeze damage or other mechanisms can also break concrete.
Concrete cancer is a process
Where corrosion is involved, rust expansion can crack and dislodge the surrounding concrete. A lasting repair needs to address the cause and the steel, not only the surface.
Why diagnosis matters
Treating every spall as the same problem can lead to poor repair decisions. The substrate, steel and exposure need to be assessed.
What to do next
Take clear photos of the wider area and close up damage, note the property location and where the concrete is situated, then arrange an on site assessment so the repair scope can be priced accurately.