Combine any like terms in the expression. If there are no like terms, rewrite the expression.

To combine like terms in the expression \( q^3 - q^3 + 8p^3 \):

1. The terms \( q^3 \) and \( -q^3 \) are like terms and will cancel each other out: \[ q^3 - q^3 = 0 \]

2. The remaining term is \( 8p^3 \).

So, the simplified expression is: \[ 8p^3 \]

Thus, the final answer is \( 8p^3 \).