Author reply

Abstract

We agree that tumor size or amount of prostatic carcinoma in radical prostatectomy tissues is an important prognostic indicator. Indeed, in the prostate, increasing tumor size has been linked to increasing pretreatment serum prostate specific antigen (PSA) level, increasing histologic grade, increased DNA aneuploidy, increasing surface area of capsular penetration, pathologic stage, an increased risk of positive surgical margins at radical prostatectomy, an increased incidence of pelvic lymph node metastases, an increased risk of failure after therapy, and an increased risk of death due to prostatic carcinoma.1 Moreover, all definitions of clinically significant versus potentially insignificant prostatic carcinomas incorporate tumor size measurements.1 Regarding determination of percentage carcinoma as a measure of prostatic carcinoma size, Dr. Renshaw states that “there is substantial circumstantial evidence to suggest that this method may be neither accurate nor reproducible in other hands,” but he does not provide any data or references in support of this statement. He also writes that “many good surgical pathologists insist upon measuring the length of tumor in a prostate needle biopsy before making an estimate of the percentage involvement.” Do any survey data exist to support this contention regarding practice patterns? Dr. Renshaw states that we suggested “that measuring the maximum tumor dimension is less valuable because it fails to account for more than one tumor focus.” In fact, the concern that we raised in our paper is that in this era of PSA screening, a dominant nodule does not often exist to allow for the measurement of maximum tumor dimension. Data exist on this issue, as in a recent large series where almost 40% of radical prostatectomies did not have an index or dominant tumor.2 The main issue here is this: Which method is best for measuring tumor size in radical prostatectomy tissues? In research settings, complete embedding of all prostatic tissue and computer-assisted measurement of tumor volume has been the gold standard. In everyday practice, this is not feasible, and in only 12% of hospitals nationwide is there complete embedding of radical prostatectomy tissue.3 There are a number of viable approaches to routine measurement of tumor size in partially embedded radical prostatectomy specimens, including assessment of percentage carcinoma and maximum tumor size. Determination of percentage carcinoma is an approach that has been applied to needle biopsy tissue,4, 5 transurethral resection of prostate (TURP) chips,6 and radical prostatectomy tissues.1, 7 In needle biopsy tissue, percentage carcinoma has been linked to pathologic stage.4, 5 In TURP chips, percentage of tissue involvement is central to staging of incidentally-detected prostatic carcinoma.8 In our studies, percentage carcinoma in radical prostatectomy tissues, assessed by a grid morphometric technique or visual inspection, has been related to progression and survival after surgery.7, 9-11 The grid method is reproducible9 and may be more quantitative, but the visual inspection method is just as strongly linked to tumor volume1 and is related to clinical progression after surgery.7 We concur with Dr. Renshaw that prostate carcinoma size should be provided in radical prostatectomy specimen reports. Currently, the Association of Directors of Anatomic and Surgical Pathology recommends reporting tumor amount in radical prostatectomy specimens as “percentage of the prostate involved by carcinoma in relation to the weight of the specimen.”12 The College of American Pathologists (CAP) suggests the following: “In subtotal and radical prostatectomy specimens, the percentage of tissue involved by tumor can also be eyeballed. Additionally, in these latter specimens it may be possible to measure a dominant tumor nodule in at least two dimensions and to indicate the number of blocks involved by tumor over the total number of blocks submitted.”13 The CAP recommends, for protocol reporting on all prostatic tissues, that “at the very least, the proportion (percentage) of prostatic tissue involved by tumor be included for all specimens.”13 Peter A. Humphrey M.D., Ph.D.*, * Washington University School of Medicine, St. Louis, MO