ROLE OF PROSTATE-SPECIFIC ANTIGEN AND DIGITAL RECTAL EXAMINATION IN THE DETECTION OF PROSTATE CANCER

Prostate-specific antigen (PSA) is a kallikrein-like serine protease that is secreted exclusively by the epithelial cells of all types of prostatic tissue, benign and malignant. Its serum concentration is raised in men with prostatic disease including cancer. We have evaluated its usefulness in the diagnosis of prostate cancer by measuring serum PSA concentrations in 260 men aged 50 years or over. All had abnormalities at digital rectal examination (DRE) involving suspected cancer, signs and symptoms of benign prostatic hyperplasia and equivocal findings on DRE, and miscellaneous other conditions, including hematospermia, chronic prostatitis and microscopic hematuria. Transrectal prostatic needle biopsies were performed in the men with abnormal findings on DRE or elevated serum PSA (above 4ng/ml). Serum PSA ranged from 4.0 to 9.9ng/ml in 14 (5%) of the 260 men. Four of the men in this group (31%) who underwent prostatic biopsy had prostate cancer. Serum PSA levels greater than or equal to 10.0 ng/ml were found in 8 (3%) of the 260 men. 5 of these 8 (63%) who underwent prostatic biopsy had cancer. If DRE alone had been used to screen the men having biopsies, 4 of the 10 cancers (40%) would have been missed. If PSA alone had been used to screen these men, only 1 of the 10 cancers would have been missed. Serum PSA measurement was more reliable than DRE for detecting prostate cancer. Since these two methods do not always detect the same malignant tumor, the combined use of DRE and PSA testing affords a more complete evaluation of the prostate gland for malignant involvement.     

PROSTATE-SPECIFIC ANTIGEN IN MASS SCREENING FOR CARCINOMA OF THE PROSTATE

Background:
Prostate-specific antigen (PSA) has various advantages over prostatic acid phosphatase (PAP) as a marker for prostate cancer, but its role in prostate cancer mass screening remains controversial. We measured serum PSA in addition to serum PAP determination and digital rectal examination (DRE) in our mass screening program to assess the usefulness of PSA for prostate cancer mass screening.
Methods:
Serum PSA and PAP measurements and DRE were performed in 1249 patients in mass screening for carcinoma of the prostate in 1989 and 1990. Thirteen cancers were diagnosed. We calculated the mean plus standard deviations (2SD) of the PSA and PAP values of men without cancer, and assessed the usefulness of PSA for prostate cancer screening by using these figures as the upper limit of normal.
Results:
The number positive for PSA, PAP and DRE were 39, 36 and 48, respectively. If our screening had been performed without DRE, three cancers would have remained undetected, and the number would have been the same if performed without PSA. If the screening had been performed without PAP, on the other hand, no cancers would have remained undetected. The sensitivities of PSA and PAP were 54% and 23%, respectively. The screening detection rate with DRE and PSA was 0.88%, and with DRE and PAP was 0.64%.
Conclusions:
Measurement of serum PSA values with adjustment of the cut-off value was considered more useful than PAP in mass screening for prostate cancer.     

DIGITAL RECTAL EXAMINATION AND IMAGING STUDIES ARE UNNECESSARY IN MEN WITH UNDETECTABLE PROSTATE SPECIFIC ANTIGEN FOLLOWING RADICAL PROSTATECTOMY

PURPOSE: We determine the probability of local or distant recurrence following radical prostatectomy in men with an undetectable prostate specific antigen (PSA) level. MATERIALS AND METHODS: The clinical course of 1,916 consecutive men followed during a 14-year period after radical prostatectomy was reviewed. Average followup plus or minus standard deviation is 5.5+/-3.5 years, and 326 men (17%) have been followed for more than 10 years. In total this population of men has been followed for 10,540 patient-years. RESULTS: Of 1,916 men 56 (2.9%) had local recurrence an average of 6.1+/-2.7 years (range 1 to 12) after surgery. No man had local recurrence with an undetectable serum PSA. Mean serum PSA at the time of local recurrence was 5.8 ng./ml. Of the 56 men 13 (25%) who had local disease recurrence had an undetectable serum PSA at 5 years of followup but had progression to biochemical and local disease recurrence later. Of 1,916 men 118 had distant metastases with a mean serum PSA of 28.6 ng./ml. No man has had distant metastasis with an undetectable serum PSA. CONCLUSIONS: Disease can recur after radical prostatectomy even after an extended biochemical disease-free interval. None of the 1,916 men followed for an average of greater than 5 years after surgery had local recurrence or distant metastasis with an undetectable serum PSA. Based on these observations, we recommend no further evaluation, that is digital rectal examination or imaging studies, in men with an undetectable PSA following radical prostatectomy.     

SERIAL PROSTATE SPECIFIC ANTIGEN, FREE-TO-TOTAL PROSTATE SPECIFIC ANTIGEN RATIO AND COMPLEXED PROSTATE SPECIFIC ANTIGEN FOR THE DIAGNOSIS OF PROSTATE CANCER

Purpose: The free-to-total prostate specific antigen (PSA) ratio and complexed PSA have been introduced as adjuncts to total PSA for prostate cancer screening. Little data exist on the use of these tests for serial PSA screening. We compared serial total PSA, the free-to-total PSA ratio and calculated complexed PSA in men diagnosed with prostate cancer and matched controls in a population based study.Materials and Methods: We identified 90 men diagnosed with prostate cancer between 1988 and 1996 with at least 3 serial serum samples obtained at 2-year intervals who were participants in the beta-Carotene and Retinol Efficacy Trial for the prevention of lung cancer. Samples were available up to 10 years before diagnosis. A total of 90 age matched men from the same cohort without prostate carcinoma were identified as controls. Free and total PSA was measured by the Abbott AxSYM system.Results: Baseline demographics of cases and controls were similar. At baseline and diagnosis the men with prostate cancer had higher total and complexed PSA, and a lower free-to-total PSA ratio than controls. Mean followup was 5.2 years in cases and 5.5 in controls. The yearly change in PSA parameters in cases versus controls was 20.7% versus 3.5% for total, -3.4% versus 0.2% for free-to-total and 21.5% versus 3.4% for complexed PSA (p <0.0001). At diagnosis PSA alone was estimated to perform with more than 90% specificity in our model.Conclusions: In this population based study total PSA was superior to the free-to-total PSA ratio for predicting the development of prostate cancer. While serial changes in free-to-total PSA ratios with time were statistically significantly different in men diagnosed with prostate cancer and controls, the magnitude of these serial changes were slight enough to render them clinically insignificant.     

SERUM HETEROPHILE ANTIBODIES INTERFERE WITH PROSTATE SPECIFIC ANTIGEN TEST AND RESULT IN OVER TREATMENT IN A PATIENT WITH PROSTATE CANCER

PURPOSE: We evaluated how naturally occurring heterophile antibodies in patient serum interfered with prostate specific antigen (PSA) immunoassay, resulting in over treatment for prostate cancer. MATERIALS AND METHODS: Serum samples were treated with heterophilic blocking reagent (Scantibodies Laboratory, Inc., Santee, California). Treated and untreated samples were tested by the Medics (Tosoh, Foster City, California ) Tandem-R (Beckman-Coulter Inc., Chaska, Minnesota) and Elecsys (Roche Molecular Biochemical, Indianapolis, Indiana) PSA assays. Heterophile antibodies were measured directly in treated and untreated samples by the human anti-mouse antibody immunoradiometric assay and heterophilic antibody identification enzyme immunoassay (Scantibodies Laboratories, Inc.). RESULTS: Human anti-mouse Ig heterophile antibodies in patient serum caused false-positive PSA test findings after radical prostatectomy, resulting in over treatment for presumed disease recurrence. CONCLUSIONS: If PSA is detectable after radical prostatectomy and the likelihood of incomplete resection or systemic disease is low, the presence of heterophile antibodies should be considered.     

RELATIONSHIP BETWEEN SYSTEMATIC BIOPSIES AND HISTOLOGICAL FEATURES OF 222 RADICAL PROSTATECTOMY SPECIMENS: LACK OF PREDICTION OF TUMOR SIGNIFICANCE FOR MEN WITH NONPALPABLE PROSTATE CANCER

PURPOSE: Because of the recent increase in nonpalpable prostate cancer (clinical stage T1c) in men, preoperative needle biopsy findings have had an important role for treatment decisions. We examine the correlation among histopathological features of 6 systematic biopsies and radical prostatectomy specimens in which 1 investigator reviewed all histological sections. MATERIALS AND METHODS: We studied a total of 450 men with clinical stage T1c prostate cancer from whom needle biopsies were matched with radical prostatectomy specimens, and selected 222 patient biopsies that were obtained from 6 or more separate regions of the prostate. The pretreatment parameters of serum prostate specific antigen (PSA), PSA density, number of positive needle biopsies, distribution of positive cores, linear cancer length, and percent Gleason grade 4/5 on the biopsy were determined and compared with histopathological features of prostate cancer in the radical prostatectomy specimens. All biopsies and radical prostatectomies were evaluated morphologically at the department of urology. RESULTS: Of the 222 men the largest cancer was clinically insignificant in 23 (10%), as measured by a cancer volume of less than 0.5 cc. Cancer volume in the prostatectomy specimen was significantly related to all parameters in the biopsy, with the surprising exception of cancer distribution in the positive biopsies. However, all of these correlations with cancer volume were weak, with Pearson's correlation squared (R(2)) multiplied by 100 less than 10%. Unfortunately, tumor grade on the biopsy agreed with the prostatectomy specimen in only 81 of 222 (36%) cases. Grade assessment with needle biopsy underestimated the tumor grade in 102 (46%) cases and overestimated it in 39 (18%). No single parameter in the biopsy was a predictor of tumor significance, as measured by a cancer volume of greater than 0.5 cc. However, the best model to predict a tumor less than 0.5 cc in volume was the combination of a single positive core with cancer length less than 3 mm. that contained no Gleason grade 4/5. The use of PSA or PSA density in combination with needle biopsy findings did not enhance prediction of tumor significance. CONCLUSIONS: These results indicate a weak and disappointing correlation among all pathological features of 6 systematic biopsies and radical prostatectomy specimens. The combination of 1 positive core with cancer length less than 3 mm. that contains no Gleason grade 4/5 is probably the best predictor of prostate cancer less than 0.5 cc in men with nonpalpable tumors, a cancer volume that occurred in only 10% of the 222 (23) men.     

VALIDITY OF THE PROSTATE SPECIFIC ANTIGEN TEST FOR PROSTATE CANCER SCREENING: FOLLOWUP STUDY WITH A BANK OF 21,000 SERA IN FINLAND

PURPOSE: We investigate the validity of prostate specific antigen (PSA) as a screening test for prostate cancer. MATERIALS AND METHODS: A registry of serum samples drawn from 1968 to 1976 from 21,387 men was linked to the Finnish Cancer Registry. During followup from 1968 to 1991, 104 prostate cancers were identified. A matched case control design with incidence density sampling and nested in the serum sample bank was applied, and PSA was assessed. RESULTS: The estimated sensitivity of the test was 44% and specificity 94% at a cutoff of 4.0 microg./l. in the total material. The sensitivity had improved to 86% in patients diagnosed in 5 years after the sample drawing. The test had a better sensitivity (93%) and specificity (96%) in men younger than 65 years at the time of the sample drawing compared to those older. The sensitivity further improved to 100% with a cutoff of 2.5 microg./l. CONCLUSIONS: PSA is a valid screening test for prostate cancer, which compares favorably with mammography for breast cancer. However, until an effect on mortality has been shown, routine screening cannot be recommended.     

PREDICTION OF POST-RADICAL PROSTATECTOMY PATHOLOGICAL OUTCOME FOR STAGE T1c PROSTATE CANCER WITH PERCENT FREE PROSTATE SPECIFIC ANTIGEN: A PROSPECTIVE MULTICENTER CLINICAL TRIAL

PURPOSE: Prostate specific antigen (PSA) exists in bound (complexed) and unbound (free) forms in serum. The percentage of free PSA enhances the specificity of PSA testing for prostate cancer detection. We evaluated the use of percent free PSA preoperatively to predict pathological stage. MATERIALS AND METHODS: A total of 379 men with prostate cancer and 394 with benign prostatic disease 50 to 75 years old were enrolled in this prospective study at 7 medical centers. All subjects had a palpably benign prostate gland, serum PSA 4.0 to 10.0 ng./ml. and a histologically confirmed diagnosis. The Hybritech Tandem PSA and free PSA assays were used. Of the 379 cancer patients 268 (71%) underwent radical prostatectomy. RESULTS: Higher percent free PSA levels were associated with more favorable histopathological findings in prostatectomy specimens. A value of 15% free PSA provided the greatest discrimination in predicting favorable pathological outcome. Organ confined cancer, Gleason sum less than 7 and small tumors (10% or less involvement of the prostate) were noted in 75% of patients with greater than 15% and only 34% with 15% or less free PSA (p<0.001). Multivariate logistic regression analysis revealed percent free PSA to be the strongest predictor of postoperative pathological outcome (odds ratio 2.25), followed by biopsy Gleason sum (2.06) and patient age (1.35). Total PSA was not predictive in this cohort but has been shown in prior studies to be predictive of outcome when a broader range of PSA values is evaluated. CONCLUSIONS: Percent free PSA may be used for risk assessment of the presence (diagnosis) and stage of prostate cancer in men with PSA between 4 and 10 ng./ml. Percent free PSA may be combined with PSA, digital rectal examination and biopsy findings to help predict postoperative pathological stage and grade, and may assist the patient and physician in making more informed treatment decisions.     

Prostate cancer detection upon transrectal ultrasound-guided biopsy in relation to digital rectal examination and prostate-specific antigen level: what to expect in the Chinese population?

We investigated the prostate cancer detection rates upon transrectal ultrasound (TRUS)-guided biopsy in relation to digital rectal examination (DRE) and prostate-specific antigen (PSA), and risk factors of prostate cancer detection in the Chinese population. Data from all consecutive Chinese men who underwent first TRUS-guided prostate biopsy from year 2000 to 2013 was retrieved from our database. The prostate cancer detection rates with reference to DRE finding and PSA level of < 4, 4–10, 10.1–20, 20.1–50 and > 50 ng ml⁻¹ were investigated. Multivariate logistic regression analyses were performed to investigate for potential risk factors of prostate cancer detection. A total of 2606 Chinese men were included. In patients with normal DRE, the cancer detection rates were 8.6%, 13.4%, 21.8%, 41.7% and 85.2% in patients with PSA < 4, 4–10, 10.1–20, 20.1–50 and > 50 ng ml⁻¹ respectively. In patients with abnormal DRE, the cancer detection rates were 12.4%, 30.2%, 52.7%, 80.6% and 96.4% in patients with PSA < 4, 4–10, 10.1–20, 20.1–50 and > 50 ng ml⁻¹ respectively. Older age, smaller prostate volume, larger number of biopsy cores, presence of abnormal DRE finding and higher PSA level were associated with increased risk of prostate cancer detection upon multivariate logistic regression analyses (P < 0.001). Chinese men appeared to have lower prostate cancer detection rates when compared to the Western population. Taking the different risk factors into account, an individualized approach to the decision of TRUS-guided biopsy can be adopted.     

Screening for prostate cancer without digital rectal examination and transrectal ultrasound: results after four years in the European Randomized Study of Screening for Prostate Cancer (ERSPC), Rotterdam

BACKGROUND: Omission of DRE/TRUS as biopsy indication results in fewer unnecessary biopsies, but may increase the risk of missing potentially aggressive prostate cancers (PCs). In 1997, the biopsy indication within the ERSPC was changed from a PSA cut-off of 4.0 ng/ml and/or abnormal DRE/TRUS (group-1) to solely a PSA cut-off of 3.0 ng/ml (group-2). We estimated the effect of omitting DRE/TRUS by comparing the results of a re-screening 4 years after initial screening to the original policy. METHODS: We compared rate and characteristics of detected PCs in the second round in men initially screened in group-1 (N=5,957) or group-2 (N=8,044). Additionally, we compared the rate of interval cancers (ICs) after screening with and without DRE/TRUS. RESULTS: There was no significant difference in second round cancer-detection-rates (group-1, 3.0%; group-2, 2.7%), positive-predictive-values (group-1, 23.9%; group-2, 26.3%), and number of poorly-differentiated tumors (group-1, 2.6%; group-2, 3.8%). Most PCs were clinically confined to the prostate. Eleven ICs were detected in each group (0.18 and 0.14%). CONCLUSIONS: Omitting DRE/TRUS did not result in an increased IC- or PC-detection. However, considering the natural history of PC, the 4-year follow-up may be too short to draw a definitive conclusion.     

9+X法直肠超声引导下经会阴前列腺穿刺活检420例分析

目的:探讨9+X法经直肠超声引导下经会阴前列腺穿刺活检术诊断前列腺癌的临床价值及安全性。方法:回顾性分析2004年1月至2008年12月行9+X法经直肠超声引导下经会阴前列腺穿刺活检术的可疑前列腺癌患者420例临床资料。结果:穿刺确诊前列腺癌160例(阳性率38.1%)。PSA<4μg/L、4～10μg/L、>10μg/L、直肠指检(DRE)异常、经直肠或经腹部超声检查有异常者阳性率分别为7.4%、17.8%、65.4%、25.0%、22.2%。穿刺术后79例出现血尿(18.8%),急性尿潴留13例(3.1%),发热9例(2.1%),无其他严重并发症。结论:9+X法经直肠超声引导下经会阴前列腺穿刺阳性率高,并发症少,是诊断前列腺癌的理想方法。     

ASSESSMENT OF SEXTANT BIOPSY OF THE PROSTATE FOR DETECTING CANCER PRIOR TO THERAPY IN PATIENTS CLINICALLY DIAGNOSED AS BENIGN PROSTATIC HYPERPLASIA

Pathological results and perioperative morbidity were compared in 199 patients who had undergone prostatectomy and/or biopsy in order to determine the extent to which systematic biopsy is effective for detecting prostate cancer prior to therapy in patients clinically diagnosed as having benign prostatic hyperplasia. Seventeen (8.5%) cancers were detected in 199 patients following surgery and/or biopsy. Digitally-guided biopsy as a means of detecting prostate cancer was found to be just as effective as ultrasound-guided biopsy. Seven (12.5%) cancers were detected in 56 patients who had undergone biopsy and transurethral resection. Preprostatec to my biopsy detected only two of three patients with stage TIb disease. All four stage TIa and one stage TIb failed to be diagnosed. Of 90 patients who had biopsy prior to surgery other than TURP, seven (7.8%) cancers were found. Four of these were advanced. The incidence of postoperative fever > 38.0 °C and duration of postoperative pyuria did not differ significantly between groups with or without biopsy. Preoperative biopsy did not contribute to perioperative morbidity. Tumors detected by systematic biopsy are usually large and clinically significant. Positive biopsy results are often diagnostic, but the pathological features of a tumor together with clinical parameters should be considered to reduce the chance of overdiagnosing an insignificant tumor. Sextant biopsy would be most applicable to patients scheduled for any type of therapy other than TURP especially in those with markedly elevated serum PSA levels. This procedure may be beneficial particularly for younger patients with long life expectancy who will benefit from definitive therapy.     

Clinicopathological Features of Prostate Cancer Detected by Transrectal Ultrasonography-Guided Systematic Six-Sextant Biopsy

Background :
The objectives of this study were to compare the efficacy of 3 modalities (prostate-specific antigen (PSA) assay, digital rectal examination (DRE), and transrectal ultrasonography (TRUS)) in detecting prostate cancer which was pathologically confirmed by TRUS-guided systematic six-sextant biopsy, and to investigate the relationship between the number of positive cores and several clinicopathological parameters.
Methods :
Between 1 992 and 1994, 297 males (155 from a mass screening program and 142 identified as outpatients) with a mean age of 71 years, underwent examinations including PSA determination, DRE, TRUS and systematic six-sextant biopsy, and/or additional directed biopsy.
Results :
Prostate cancer was detected in 93 men. The sensitivity level of the PSA assay was significantly higher (85%) than that of either DRE or TRUS. Patients with an abnormal DRE or TRUS, elevated PSA levels, and those in the T3-T4 category or with moderate to poorly-differentiated adenocarcinomas had more positive biopsy cores (P< 0.05). Also, the relationships of both the number of positive biopsy cores and tumor grade to bone metastasis were significant (P < 0.01). Of 209 hypoechoic areas identified by transrectal ultrasonography, 42% were cancerous, and of 427 isoechoic areas, 1 2% were cancerous. The percentage of positive biopsy cores with hypoechoic areas was 86% in the subjects with a PSA > 10 ng/mL, but low (9%) in subjects with a PSA < 4 ng/mL, and the percentage of negative biopsy cores with a normal TRUS was high (98%) in subjects with a PSA of < 4 ng/mL, but lower (67%) in subjects with a PSA > 10 ng/mL.
Conclusion :
The serum PSA assay was more useful than either DRE or TRUS in detecting prostate cancer. The percentage of bone metastasis increased concomitant with the number of positive biopsy cores, and the positive biopsy rate of hypoechoic areas positively correlated with the PSA level.     

DIURNAL RHYTHM OF SERUM gM-SEMINOPROTEIN IN PATIENTS WITH UNTREATED PROSTATE CANCER: COMPARISON OF THE ORIGINAL AND REVISED ASSAY KITS

To compare levels of y-seminoprotein (gM-Sm) assayed by original and revised assay systems, blood was obtained every 4 h over a 32-h period from 8 untreated prostate cancer patients. Serum levels of prostate specific antigen (PSA) were also examined. In 6 patients, the coefficient of variation (CV) of the serum levels assayed by the revised assay was significantly different from that of the intra-assay samples. In contrast, the CV of the gM-Sm serum levels assayed by the original assay differed significantly from that of the intra-assay samples in only 2 patients. The fluctuations in gM-Sm assayed by the revised assay were, at least in part, similar to those of the PSA serum levels in all patients. The mean CV of the gM-Sm serum levels assayed by the revised assay was significantly larger than that for levels measured by the original assay. After treatment, the rate of decrease in gM-Sm serum levels determined by the original assay differed from that in the serum levels of PSA and prostatic acid phosphatase. These results indicate that the original assay for gM-Sm do not detect diurnal differences in serum gM-Sm levels, even at levels below 20 ng/ml. These observations indicate that the analysis of data obtained using the original gM-Sm kit should be interpreted with caution.     

THE EFFECT OF HIGH GRADE PROSTATIC INTRAEPITHELIAL NEOPLASIA ON SERUM TOTAL AND PERCENTAGE OF FREE PROSTATE SPECIFIC ANTIGEN LEVELS

PURPOSE: It is established that the percentage of free prostate specific antigen (PSA) in serum is low in patients with prostate cancer. An unanswered question is whether a low percentage of free PSA can be explained by high grade prostatic intraepithelial neoplasia alone. We compared the percentage of free PSA in men with high grade prostatic intraepithelial neoplasia alone, prostate cancer, benign prostatic hyperplasia (BPH) and a normal prostate (that is normal digital rectal examination and PSA less than or equal to 2.5 ng./ml.). MATERIALS AND METHODS: From October 1994 through December 1997, 48 men were diagnosed with high grade prostatic intraepithelial neoplasia without concomitant prostate cancer. Of these men 43 with a mean age plus or minus standard deviation of 67.4 +/- 7.8 years comprised our study group. To date none has been diagnosed with cancer during followup. Serum free and total PSA levels were measured, and the percentage of free PSA was calculated. The percentage of free PSA in the 43 men was compared to that in 50 with prostate cancer (mean age 65.4 +/- 7.8 years), 50 with biopsy proved BPH (67 +/- 7) and 43 with a normal prostate (61 +/- 8). RESULTS: There was no significant difference in mean total serum PSA in patients with high grade prostatic intraepithelial neoplasia, prostate cancer or BPH. The percentage of free PSA was significantly lower in patients with prostate cancer (14.9 +/- 6.5%) than those with high grade prostatic intraepithelial neoplasia (20.8 +/- 7.1%), BPH (20.1 +/- 7.3%) or a normal prostate (27.7 +/- 12.2%). There was also no significant difference in the percentage of free PSA between men with high grade prostatic intraepithelial neoplasia (20.8 +/- 7.1%) and those with BPH (20.1 +/- 7.3%). Additionally, men with a normal prostate had a higher percentage of free PSA (27.7%) than those with BPH (20.1%), high grade prostatic intraepithelial neoplasia (20.8%) or prostate cancer (14.9%). CONCLUSIONS: The percentages of free PSA in men with high grade prostatic intraepithelial neoplasia and BPH are similar, and significantly higher than those found in men with prostate cancer.     

低位直肠癌保肛手术适应证选择与评价

目的：探讨低位直肠癌保肛手术适应证选择标准评价保肛术后临床效果。方法：根据肛门指诊、直肠腔内超声、盆腔ＣＴ、ＭＲＩ、术前活检病理，在２６５例低位直肠癌中选择１５５例和支撑吻合管经肛门环扎式结肠－直肠（肛管）吻合术。低位直肠保肛手术适应证选择标准：高中分化腺癌、隆起型、未浸透深肌层、环周度≤１／２周，无肠旁淋巴结肿大、距齿状线１ｃｍ以上。高中分化腺癌、溃疡型≥１／２周，浸透肠壁深肌层、无盆腔淋巴结肿