Dear A husband: The most important consideration is that Tamoxifen of other hormone-related treatment will not be helpful. That said, hormone receptor negative tumors appear to be more aggressive. It is difficult, however, to say that this is the only variable, since there are so many other factors that contribute to the behavior of tumors - including size, lymph node involvement, and Her2neu status to name a few.
In general, receptor negative tumors are felt to behave a bit more aggressively than hormone positive ones. So yes, there's more to it than just not being amenable to hormone therapy. But there are other factors which affect prognosis more significantly; namely, tumor size, lymph node status, etc.