I'm told I need to take remicade, (infliximab) im worried about what the most common side effect is and is cancer somthing I should be concerned about getting?

Possibly. Remicade (infliximab) increases infections, including sinus/respiratory infections and severe infections (fungus or tuberculosis.) allergic reaction during infusion is a common side effect. It also increases risk for cancer, particularly lymphomas (3-4x increased risk). Head and neck cancers are increased in people with copd. Really ask your doctor about this so you can balance your risks and benefits.
Mild. Cancer is unlikely. Data suggest that only risk of non-melanoma skin cancer is slightly increased from remicade (infliximab). Most common side effects are common infections, headache, abdominal pain and infusion reactions. Most are mild.