Using a large population-based sample of localized prostate cancer cases from diverse regions of the country diagnosed in 2004, we found that AS was used to manage 4.7% of all men sampled and by 6.4% of those in the clinically low-risk disease category. With older age and severity of comorbidities being the strongest predictive factors for its use, it is clear that the practice of recommending AS for the healthy younger man with low-risk disease was not widely adopted at that time. The association of use of AS with older age was similar to that reported in the CaPSURE study based on men diagnosed between 1999 and 2004, where older age was the only demographic predictor (9
). Although they found a somewhat higher proportion of the lower risk men using AS (9%), they were able to more specifically identify very low-risk men based on PSA density and number of positive biopsy cores, which were not available in this study.
These findings suggest that physicians still feel more comfortable recommending AS for men with lower life expectancy and more severe comorbidities that may preclude use of surgery or other aggressive therapy. Thus, physicians may be unwilling to recommend AS for younger men or those without comorbidities due to uncertainty regarding which selection criteria to use and due to patients’ anxiety about monitoring their disease instead of having definitive treatment. In one study examining urologists recommendations for low-risk prostate cancer, AS was discussed 25% of the time vs 80% for prostatectomy (22
In addition to those receiving AS, we found that 8.6% received NT/NP, bringing the total proportion of men receiving no therapy in the first 6 months after diagnosis to 13.3%. In another registry-based patterns of care study by the National Cancer Institute’s SEER cancer registries, no treatment (due to any reason) within the first 6 months after diagnosis was found for 12.6% of men with clinically localized prostate cancer in 1998 and 9% in 2002 (23
). It is possible that there was some increase in the overall proportion receiving no therapy between 2002 and 2004, but it cannot be determined if it was due to an increase in those receiving AS vs having NT/NP or due to differences in the characteristics of the patients included in each of these studies.
In contrast to those receiving AS, we found that men with NT/NP were more likely to be from areas with fewer urologists and also more likely to be nonwhite. In the univariate analyses, they were also more likely to be from lower socio-economic areas, although this variable was not significant in the multivariable models. Because no specific mention of any form of observation was indicated in the medical record, these men may have taken longer to decide on what therapy to pursue or may be having delays in receiving care due to problems with access to care. From additional review of the medical record data in the POC-BP study, we found that 35% of them (compared with less than 5% of AS patients) did receive some type of therapy after 6 months, indicating that delay in therapy was an important factor for men in the NT/NP group. The men with delay were more likely to be younger than those who continued with no therapy and were also more likely to be in the lowest clinical risk group.
Another concern with the NT/NP group is that medical records containing information about their therapy may have been missing or unavailable for abstraction. Although we removed patients with missing data in other variables from the multivariable models, we had an additional variable on the source of information abstracted for each case and found that (after removing those with missing data) physician office records were less likely to be reviewed for the NT/NP group compared with those receiving AS (44.2% vs 69.4%), thus missing outpatient treatment information may also be a factor.
Although registry-based studies are helpful in deriving population-based estimates of use of specific therapies, there are limitations in the types of data that are available. Only data available for abstraction in medical records are included, and although efforts were made to obtain physician and outpatient records, this was not possible for all cases. Thus, information about use of specific monitoring plans may be underreported. Other sources of data including claims information, or additional review of medical records for evidence of repeat PSAs, or return visits to urologists or radiation oncologists during the 6-month period after diagnosis may provide evidence of monitoring, even if not explicitly stated in the medical record. This type of information was not available for this study, however. Another limitation is the year of diagnosis (2004) on which these results are based. Although we were able to compare use of AS with other data sources from this same time period, the currently changing viewpoint on use of AS, especially regarding its use for younger men with potentially curable disease, is a more recent development, which may not have been widely accepted at the time these men were diagnosed. Nevertheless, the data presented here provide an important baseline for assessing changes in the use of this management option. In order to be able to do this using cancer registry data, which routinely include PSA, biopsy-derived Gleason score, and clinical T stage, there are other AS selection criteria proposed, such as PSA density, tumor percentage within biopsy cores, as well as number of positive biopsy cores (24
) that should be abstracted in future studies. If definitive AS selection criteria could be determined from the different options being considered (6
), cancer registries could be a valuable resource to obtain additional predictors of progression that could be used to assess the number of patients that may ultimately benefit from AS and monitor the use of this approach among clinically eligible men from a population-based perspective.