Lineability of summing sets of homogeneous polynomials

Given a continuous $n$-homogeneous polynomial $P\colon E\longrightarrow F$ between Banach spaces and $1\leq q\leq p<\infty$, in this paper we investigate some properties concerning lineability and spaceability of the $(p;q)$-summing set of $P$, defined by $S_{p;q}(P)=\{a\in E:P\mathrm{is}% (p;q)\mathrm{summing at}a\}$.