Rich G,
First of all, with 4+4 post surgical pathology, you already know you have a challenging case...
I just read an interesting paper co-authored by Epstein in the American Journal of Surgical Pathology (2004) which examined the effect of tertiary Gleason pattern 5 on 3+4 cases, 4+3 cases and 4+4 cases.
I'll provide the link, below, and suggest you read for yourself, but my summary of the findings with regard to your case is as follows: The tertiary pattern 5 did have an unfavorable influence on the two types of Gleason score 7 cases studied, but did NOT significantly negatively change the outcomes of the 4+4 cases. The 4+4+5 cases acted mostly like 4+4 cases, whereas some of the Gleason score 7 cases acted like higher grade cases.
In the Discussion section, the authors speculated as to why there was more significant negative impact on the Gleason score 7 cases than the 4+4 cases: "We think that this reflects the fact that Gleason score 4+4 tumors have a sufficiently poor prognosis that tertiary Gleason pattern 5 does not confer a worse prognosis."
Prognostic Significance of Tertiary Gleason Pattern 5 in Radical Prostatectomy Specimens
The decision for ART or not (with possible SRT in the future) is difficult in the absence of clear-cut evidence one way or the other. I personally believe we (the collective "we") tend to frequently overtreat the low-risk cases and undertreat the high-risk cases. But 4+4 with positive margins; I'd say some sort of RT is in your future. Good luck.