Clinicopathological data of PT0 group
A total of 8 patients diagnosed with prostate cancer by preoperative prostate biopsy but no tumor tissue was found in the RP specimen were included in the pT0 group. Table 1 summarizes their clinicopathological features and prognostic data in detail. The mean age of the 8 patients at the time of RP was 69.1 year (range: 63–73). The clinical staging of the 7 patients was T1c, only 1 was T2a, the mean total PSA was 5.9 ng/ml (range: 2.7–11.4), and the mean prostate volume obtained by preoperative transrectal prostate ultrasound was 54.2 ml (range: 35.9–74.8). Gleason score of prostate biopsy was 5 in 1 case and 6 in others. Except for the presence of prostate nodules in 1 case, two needle biopsies were added, and the remaining 7 cases were standard 12-needle biopsy. The number of positive biopsy cores were 2 in only one patient, and 1 in all the other patients. The positive length of tumor biopsy in all patients was less than 2 mm. It is worth noting that half of the patients had been taking finasteride for a long time (More than three months) before the RP due to lower urinary tract symptoms.
Table 1
Clinicopathological features and follow-up data of 8 pT0 patients
Clinical data | | biopsies data | | RP specimen data | | Follow-up and prognosis |
Patient | Age | Preoperative Finasteride(Y/N) | Clinical stage | tPSA | Prostate volume(ml) | | Gleason score | P/T | Length of cancer(mm) | Location | | HGPIN/ASAP | | Follow-up(mon) | Alive(Y/N) |
1 | 69 | Yes | T2a | 11.4 | 68.9 | | 6 | 2/14 | 1&1 | Apical& nodule | | ASAP&HGPIN | | 143 | Yes |
2 | 70 | Yes | T1c | 4.5 | 57.4 | 6 | 1/12 | 1 | Middle | HGPIN | 125 | Yes |
3 | 63 | No | T1c | 4.1 | 41.2 | 6 | 1/12 | 1 | Apical | ASAP | 112 | Yes |
4 | 72 | No | T1c | 4.2 | 43.2 | 6 | 1/12 | 1 | Apical | HGPIN | 82 | Yes |
5 | 70 | Yes | T1c | 2.7 | 74.8 | 6 | 1/12 | 1 | unknown | BPH | 66 | Yes |
6 | 64 | No | T1c | 4.3 | 35.9 | 5 | 1/12 | 1 | Apical | ASAP | 46 | Yes |
7 | 73 | No | T1c | 9.8 | 66.4 | 6 | 1/12 | 1 | Posterolateral | HGPIN | 38 | Yes |
8 | 72 | Yes | T1c | 6.6 | 45.7 | 6 | 1/12 | 2 | left basal part | HGPIN | 19 | Yes |
ASAP: atypical small acinar proliferation; HGPIN: high-grade prostatic intraepithelial neoplasia; BPH: benign prostate hyperplasia; P/T: number of positive biopsy cores/total number of biopsy cores; RP: radical prostatectomy. |
All prostate biopsies corresponding to pT0 specimens were reviewed by a second pathologist, and all cases were reconfirmed with prostate cancer. RP specimens from these 8 patients were evaluated by more than two pathologists, with 5 diagnosed as high-grade prostatic intraepithelial neoplasia (HGPIN), 3 diagnosed as atypical small acinar proliferation (ASAP), and 1 diagnosed as benign prostatic hyperplasia (BPH). The 8 patients were followed up for an average of 67 months(range:16–143), and all survived without biochemical recurrence or progression.
Comparison of data between groups
A total of 96 patients with complete clinicopathological features and prognostic data were included in the control group for comparison with the pT0 group. Table 2 describes the comparison of clinicopathological data between pT0 group and control group. There was no significant difference in age (P = 0.76, Student t test) and positive rate of digital rectal examination (DRE) (P = 0.431, chi-square test) between the two groups. Notably, there was a statistically significant difference in the long-term use of finasteride between the two groups (50% vs 12.5%, P = 0.018, chi-square test). In the pT0 group, the median number of positive biopsy cores was significantly lower than the control group (1 vs 3, p = 0.027, Mann-Whitney test), and the cancer length of biopsy was also significantly lower than the control group (1.3 vs 6.2 mm, p = 0.014, Student t test). The mean preoperative PSA of the pT0 group was significantly lower than that of the control group (5.9 vs 14.3, P = 0.039, Student t test), Gleason score also tended to be lower(p = 0.012, Mann-Whitney test), but the mean preoperative prostate volumewas significantly larger than that of the control group(54.2 vs 29.2, P < 0.01, Student t test).
Table 2
Comparison between the pT0 group and the control group
| Mean value or rate (range and SD) | P value |
pT0 group (n = 8) | Control group (n = 96) |
Patient age (yr) | 69.1(63–73, SD = 3.7) | 68.3(54–82, SD = 6.8) | 0.76 |
Abnormal DRE rate | 12.5% | 31.25% | 0.431 |
PSA | 5.9(2.7–11.4, SD = 3.1) | 14.3(2.7–56.5, SD = 11.3) | 0.039 |
Prostate volume(ml) | 54.2(35.9–74.8, SD = 14.6) | 29.2(12.1–74.8, SD = 12.3) | < 0.01 |
Long-term use finasteride | 50% | 12.5% | 0.018 |
Gleason score on biopsy < 7/ = 7/>7 | 100%/0%/0% | 52%/25%/23% | 0.012 |
Median no. of positive cores | 1(1–2) | 3(1–12) | 0.027 |
Length of biopsy positive for cancer(mm) | 1.3(1–2, SD = 0.5) | 6.2(1–34, SD = 5.6) | 0.014 |
DRE: digital rectal examination; PSA, prostate-specific antigen. |
Predictive model and prognostic assessments
Apart from finasteride use, the other five items were particularly frequent in the pT0 group (Table 2). we defined a cutoff that was predictive of pT0 prostate cancer : prostate-specific antigen (PSA) < 10 ng/ml, one positive biopsy core only, biopsy Gleason score < 7, and prostate volume > 40 ml, length of biopsy positive for cancer ≤ 2 mm. When these five parameters were combined as a predictive model, only 2 of the 8 pT0 prostate cancer patients were misdiagnosed, and only 1 of the 97 control patients was misdiagnosed as pT0 prostate cancer, with a sensitivity of 75%, specificity of 99%, positive predictive value of 86%, and negative predictive value of 98% (Table 3).
Table 3
The predictive power of pT0 prostate cancer based on these five characteristics
| pT0 group | Control group | Total |
5 characteristics combined | 6 | 1 | 7 |
5 characteristics not combined | 2 | 95 | 97 |
Total | 8 | 96 | 104 |
Sensitivity:75% (2/8) | Specificity:99% (95/96) |
Positive predictive value:86% (6/7) | Negative predictive value:98% (95/97) |
The survival curve provided by kaplan-meier analysis showed that the pT0 group had better overall survival than the control group of 50 patients with Gleason score less than 7, although it was not statistically significant (Fig. 1, P = 0.091).