As I understand it,
LVI indicates the cancer has acheived an intital step necessary for metastasis - but there are still many more required steps for sucessful metastasis - my radiation oncologist said there were roughly 40 steps necessary for prostate cancer metastasis. Accordingly, it is a negaitive prognostic indicator and should be routinely reported in pathology reports when present.
However, LVI is frequently accompanied by other well established negative factors i.e., high pre-op PSA, high G-score, positive margins etc. which are commonly used in monograms. Due to the lack of consensus regarding LVI's contribution to overall risk it appears to not to be used in most monograms (I've seen one). The degree of prognostic value of LVI above and beyond existing well established risk factors is not agree upon within the medical PC community.
Currently, many of the studies are based on a small sample sizes and more study is needed to quantify LVI's contribution to risk. Developing meaningfull statistically models with prognostic value requires larger sample sizes and controls for all the other various negaive factors often present with LVI.
If you believe the article cited below then current monograms tell most of the risk story already.
Urology - Volume 68, Issue 1, July 2006, Pages 99-103
"LVI is found in fewer than 10% of radical prostatectomy specimens for clinically localized disease. It is seen almost exclusively in high-volume tumors in conjunction with other adverse pathologic features. On univariate analysis, LVI was significantly associated with biochemical progression, but not with a preoperative PSAV greater than 2 ng/mL/yr. When combined with all other clinical and pathologic features in a multivariate model, LVI lost its independent prognostic significance. Thus, although the finding of LVI on a pathology report is certainly an adverse prognostic feature, it appears that its effect on the biochemical progression rate is mediated through its strong association with other adverse pathologic features."