Palliative radiation therapy for localized prostate symptoms in hormone refractory prostate cancer

Hormone refractory prostate cancer (HRPCa) can cause debilitating local pelvic symptoms including urinary obstruction, pelvic pain, haematuria and obstructive rectal symptoms. High-dose palliative radiation therapy (RT) is used in many centres to relieve these symptoms despite limited published evidence for its efficacy. This study aimed to assess if RT provides effective and durable palliation for local prostate symptoms in HRPCa. Thirty-five HRPCa patients received RT to the prostate for local symptoms between November 2002 and March 2006. The median dose was 60 Gy in 30 fractions (range 30-70 Gy). Response around a 6-month time point was scored as complete resolution, partial resolution, no change or local progression. Time to progression (defined as new or recurrent symptoms) or persistence of symptoms was recorded. Factors influencing outcome, such as dose, type and number of symptoms and previous transurethral resection, were examined. Twenty-one (60%) patients had a complete (n=3) or partial improvement (n=18) in symptoms. All three complete responders had haematuria as their only symptom. In the eight (23%) patients with local progression, half progressed during treatment and all had done so within 3 months. This series represents a bigger cohort than any reported in published works examining this issue. It suggests that radiation is effective in palliating the local pelvic symptoms in HRPCa.     

Salvage prostate brachytherapy for localized prostate cancer failure after external beam radiation therapy

PURPOSE: To determine the toxicity and clinical outcome of salvage prostate brachytherapy for localized prostate cancer failure after external beam radiation therapy. METHODS AND MATERIALS: Twenty-one patients underwent (103)Pd salvage brachytherapy (median minimum peripheral dose, 90Gy) after local failure after external beam radiation (median dose, 66.6Gy) from 1/21/1998 to 4/5/2005. The median age was 72 years. Six patients had prior transurethral resection of the prostate. The median Gleason score was 7 and the median preimplant prostate-specific antigen was 3.8. Twelve patients received concurrent androgen ablation with prostate brachytherapy. Biochemical failure was defined as three consecutive rises in prostate-specific antigen scored at the call date, initiation of hormone therapy, or clinical failure. Toxicity was defined according to the National Cancer Institute common toxicity criteria and the Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer late radiation morbidity scoring scheme. RESULTS: With a median followup of 36 months, the actuarial 3-year and 5-year overall survival rates were 81% and 81%, and the biochemical failure-free survival rates were 94% and 38%, respectively. There was no significant difference in biochemical failure-free survival (p=0.98) and overall survival (p=0.13) for patients who had androgen ablation. Four patients developed biochemical failure and 1 patient developed distant metastasis at 59 months from treatment. Four patients had Grade 2 genitourinary adverse events, 2 patients had Grade 1 genitourinary adverse events, and 1 patient had a Grade 2 gastrointestinal adverse event. There were no Grade 3 or higher adverse events. All three deaths were secondary to other medical comorbidities. CONCLUSIONS: Salvage prostate brachytherapy after external beam radiation failure can be safely performed with acceptable biochemical control. This treatment option should be considered for patients who have prolonged life expectancy after localized external beam radiation failure.     

Safety of image-guided radiotherapy in definitive radiotherapy for localized prostate cancer: a population-based analysis

Objectives:Image-guided radiotherapy (IGRT) is a recommended advanced radiation technique that is associated with fewer acute and chronic toxicities. However, one Phase III trial showed worse overall survival in the IGRT arm. The purpose of this observational study is to evaluate the impact of IGRT on overall survival.Methods:We used the Taiwan Cancer Registry Database to enroll cT1-4N0M0 prostate cancer patients who received definitive radiotherapy between 2011 and 2015. We used inverse probability treatment weighting (IPW) to construct balanced IGRT and non-IGRT groups. We compared the overall survival of those in the IGRT and non-IGRT groups. Supplementary analyses (SA) were performed with alternative covariates in propensity score (PS) models and PS approaches. The incidence rates of prostate cancer mortality (IPCM), other cancer mortality (IOCM), and cardiovascular mortality (ICVM) were also evaluated.Results:There were 360 patients in the IGRT arm and 476 patients in the non-IGRT arm. The median follow-up time was 50 months. The 5-year overall survival was 88% in the IGRT arm and 86% in the non-IGRT arm (adjusted hazard ratio [HR] of death = 0.93; 95% CI, 0.61–1.45; p = 0.77). The SA also showed no significant differences in the overall survival between those in the IGRT and non-IGRT arms. Both groups did not significantly differ in terms of IPCM, IOCM, and ICVM.Conclusions:The overall survival of localized prostate cancer patients who underwent IGRT was not inferior to those who did not.Advances in knowledge:We demonstrated that the overall survival for prostate cancer patients with IGRT was not worse than those who did not undergo IGRT; this important outcome comparison has not been previously examined in the general population.     

Australian prostate-specific antigen outcome and toxicity following radiation therapy for localized prostate cancer

The objective of the present study was to examine prostate-specific antigen relapse free survival (PSA-RFS) and morbidity following 'conventional' radical radiation therapy for prostate cancer in two Australian regional treatment services. Four hundred and eighty men with clinically localized prostate cancer were treated between 1993 and 1997 at Liverpool and Westmead Hospitals using a standardized 4-field, CT-planned radiotherapy technique. Principal endpoints were PSA-RFS (American Society for Therapeutic Radiology and Oncology guidelines definition) and late rectal and urinary morbidity (Radiation Therapy Oncology Group/European Organisation for Research and Treatment of Cancer criteria). The median follow up of patients from the end of RT was 55 months. Prospectively, they were divided into three prognostic categories: (i) high risk T3 or 4 and/or PSA > 20 ng/mL and/or Gleason score 8-10 (40% of cohort); (ii) intermediate risk T1 or 2 and PSA 10-20 ng/mL and/or Gleason score 7 (33% of cohort); and (iii) low risk T1 or 2 and PSA < 10 ng/mL and Gleason score < 6 (27% of cohort). The 5-year actuarial PSA-RFS was 53% for the whole patient group. The 4-year rates were 32, 56 and 75% for high, intermediate and low risk groups, respectively. On multivariate analysis, T-stage, Gleason score, pre-RT-PSA were strong independent predictors of PSA-defined outcome. Late (grade 2) rectal and urinary morbidity occurred at some point in time in the post-RT period in 8.0 and 5.8% of patients, respectively. These results confirm that low Gleason score, low T stage, presenting PSA < 10 ng/mL and nadir < 1 ng/mL remain the strongest predictors of a good outcome. Long-term toxicity was very acceptable. However, further improvement in outcome is desirable, and with the adoption of new technology allowing escalation of radiotherapy doses such an expectation might be achieved.     

Live implant dosimetry may be an effective replacement for postimplant computed tomography in localized prostate cancer patients receiving low dose rate brachytherapy

PurposeTo determine if Live Implant Dosimetry (LIDO) utilizing intraoperative transrectal ultrasound (TRUS) is equivalent to postimplant CT dosimetry (either day 0 or day 30) in patients with localized prostate cancer (PC) treated with low dose rate (LDR) prostate seed brachytherapy.Methods and MaterialsThe treated population consisted of 628 men with localized (T1-T2) PC. All d'Amico risk categories (low, intermediate, and high) were included, and 437 patients were treated with monotherapy (160 Gy) [low and low tier intermediate], and the remainder (191) [high tier intermediate and high risk] with an implant boost (106 Gy) post external beam radiation, to a volume including the prostate and seminal vesicles (46 Gy). LIDO with intraoperative TRUS, postimplant CT (day 0 and day 30) were performed in all cases. Prostate volumes (V), V₁₀₀ (prostate) and dose (D) D₉₀ (prostate), D₃₀ (urethra), and Rectum D_2cc, were recorded. No urinary catheter was used on Day 30 CT.ResultsMore than 91.33% of monotherapy patients reached the target D₉₀ according to LIDO while only 82.99% of Day 0 CT and 92.82% of Day 30 CT achieved target D₉₀. When considering V₁₀₀, monotherapy patients recorded target dosimetry in 90.93%, 82.31%, and 92.02% of cases assessed by LIDO, Day 0 CT and Day 30 CT, respectively. Strong correlations are observed in D₉₀, Rectum D_2cc and Urethra D₃₀ across imaging modalities but V₁₀₀ and V₁₅₀ were poorly correlated due to the relative quantification of this parameter and high degree of error in measurement. Of all monotherapy patients with satisfactory dosimetry on LIDO, 94.82% reached target D₉₀ at day 30 CT and 94.19% reached target V₁₀₀.ConclusionsLIDO and CT are both effective tools for assessing postimplant dosimetry. Patients with satisfactory LIDO dosimetry are highly likely to have equivalent dosimetry on CT at follow-up, indicating that postimplant CT may be eliminated in PC a patients implanted with this technique.     

Biologically effective dose using reciprocal repair for varying fraction doses and fraction intervals

Hyperfractionated regimes are being used more frequently; this has created a clinical need for more sophisticated biologically effective dose (BED) calculations. A formula is given for calculating BED assuming reciprocal repair in the case of changing dose per fraction and changing interfraction interval. Example applications are given for hyperfractionated schedules. It is shown that the formula is useful for calculating isoeffective schedules for a treatment with unplanned gaps and for comparing regimes in trial design. This work should be of value for comparing risk across accelerated schedules when an organ of the central nervous system is at risk. Uncertainties in choice of parameter and model are discussed: the bi-exponential model of repair is invoked for this purpose.     

CT-MRI image fusion for delineation of volumes in three-dimensional conformal radiation therapy in the treatment of localized prostate cancer

The objective of this study was to assess the utility of CT-MRI image fusion software and compare both prostate volume and localization with CT and MRI studies. We evaluated the differences in clinical volumes in patients undergoing three-dimensional conformal radiation therapy for localized prostate cancer. After several tests performed to ensure the quality of image fusion software, eight patients suffering from prostate adenocarcinoma were submitted to CT and MRI studies in the treatment position within an immobilization device before the start of radiotherapy. The clinical target volume (CTV) (prostate plus seminal vesicles) was delineated on CT and MRI studies and image fusion was obtained from the superimposition of anatomical fiducial markers. A comparison of dose-volume histograms relative to CTV, rectum, bladder and femoral heads was performed for both studies. Image fusion showed a mean overestimation of CTV of 34% with CT compared with MRI. Along the anterior-posterior and superior-inferior direction, CTV was a mean 5 mm larger with CT study compared with MRI. The dose-volume histograms resulting from CT and MRI comparison showed that it is possible to spare a mean 10% of rectal volume and approximately 5% of bladder and femoral heads, respectively. This study confirmed an overestimation of CTV with CT images compared with MRI. Because this finding only allows a minimal sparing of organs at risk, considering the organ motion during each radiotherapy session and the excellent outcomes of prostate cancer treatment with CT based target identification, we are still reluctant to reduce the CTV to that identified by MRI.     

High dose rate radiation treatment of experimental intramuscular prostate carcinoma

Purpose: The Dunning R3327-MLL is a well established transplanted tumour line, and as such it makes a desirable model for evaluative studies of therapy. In the current study, the interstitial growth characteristics as well as the response of this tumour to a single fraction of high dose rate radiation is investigated.

Materials and methods: The in vitro response to radiation of the Dunning R3327-MLL was studied via a colony forming assay using a Cs-137 irradiator. In vitro radiosensitivity was determined on tumours implanted intramuscularly in the left gastrocnemius muscle of the rat and irradiated using an Ir-192 afterloader.

Results: The results demonstrate a faster growth rate when compared to the reported subcutaneous growth rates. The Dunning R3327-MLL's radiosensitivity is comparable to that of late response tissues. The dose required to achieve a specific radiobiological response (the α:β ratio) of the in vitro cell line is 2.4 Gy, whereas the ratio for the intramuscularly growing tumour was 0.99 Gy.

Conclusions: These findings signify the intramuscularly implanted Dunning R3327-MLL tumour model as a desirable model for the study of single fraction high dose rate radiation treatments.     

Biological effective dose for comparison and combination of external beam and low-dose rate interstitial brachytherapy prostate cancer treatment plans.

We report a methodology for comparing and combining dose information from external beam radiotherapy (EBRT) and interstitial brachytherapy (IB) components of prostate cancer treatment using the biological effective dose (BED). On a prototype early-stage prostate cancer patient treated with EBRT and low-dose rate I-125 brachytherapy, a 3-dimensional dose distribution was calculated for each of the EBRT and IB portions of treatment. For each component of treatment, the BED was calculated on a point-by-point basis to produce a BED distribution. These individual BED distributions could then be summed for combined therapies. BED dose-volume histograms (DVHs) of the prostate, urethra, rectum, and bladder were produced and compared for various combinations of EBRT and IB. Transformation to BED enabled computation of the relative contribution of each modality to the prostate dose, as the relative weighting of EBRT and IB was varied. The BED-DVHs of the prostate and urethra demonstrated dramatically increased inhomogeneity with the introduction of even a small component of IB. However, increasing the IB portion relative to the EBRT component resulted in lower dose to the surrounding normal structures, as evidenced by the BED-DVHs of the bladder and rectum. Conformal EBRT and low-dose rate IB conventional dose distributions were successfully transformed to the common "language" of BED distributions for comparison and for merging prostate cancer radiation treatment plans. The results of this analysis can assist physicians in quantitatively determining the best combination and weighting of radiation treatment modalities for individual patients.     

Moderately hypofractionated radiotherapy for localized prostate cancer

Purpose

To evaluate long-term outcome after dose-escalated, moderately hypofractionated radiotherapy for prostate cancer.

Methods

Since 2005, 150 consecutive patients were treated with primary radiotherapy for localized prostate cancer. Intensity modulated radiotherapy (IMRT) using the simultaneous integrated boost (SIB) technique was practiced in all patients and doses of 73.9 Gy (n?=?41) and 76.2 Gy (n?=?109) were delivered in 32 and 33 fractions, respectively. The pelvic lymph nodes were treated in 41 high-risk patients. Treatment was delivered using cone-beam CT based image-guided radiotherapy (IGRT). Toxicity was assessed prospectively using CTCAE 3.0; biochemical failure was defined according to the Phoenix definition of nadir +?2 ng/ml.

Results

Median follow-up of living patients was 50 months. Gastrointestinal (GI) toxicity was mild with >?80?% of the patients free from any GI toxicity during follow-up and no time trend to increased rates or to higher grade of GI toxicity. Two patients suffered from late grade 3 GI toxicity. Acute genitourinary (GU) toxicity grade 1–2 was observed in 85?% of the patients; most patients recovered quickly within 6 weeks after treatment. The rate of GU toxicity grade ≥?2 was <?10?% at 6–12 month but increased continuously to 22.4?% at 60 months; grade 3 GU toxicity remained below 5?% during follow-up. The 5-year freedom from biochemical failure (FFBF) was 82?% for all patients and 88, 80, and 78?% for low-, intermediate-, and high-risk disease.

Conclusion

Favorable FFBF with simultaneously low rates of toxicity was observed after moderately hypofractionated radiotherapy with 2 Gy-equivalent doses ≥?80 Gy. Conformal IMRT planning and accurate IGRT treatment delivery may have contributed to these results.     

Tumor response and treatment complications in radiotherapy of localized prostate cancer

The response of primary tumor to definitive radiation therapy and treatment related morbidity has been analysed in a group of 35 patients. All of them were treated with 20 MeV photon beam to a total dose of 67 to 71 Gy to the prostate. The effect of radiotherapy to a primary tumor were evaluated by means of repeated CT examination of the tumor volume. A statistically significant tumor regression was found to occur from the sixth month after finishing radiotherapy. The absolute majority of treatment complications was of the first grade. Neither moderate nor severe gastrointestinal or genitourinary complications were recorded. The follow-up data of our patients have confirmed that radiotherapy in localized prostatic carcinoma, when sophisticated techniques are employed, represents highly effective treatment modality which improved the quality of life in patients with prostate cancer.     

PET-CT检查致前列腺癌患者辐射剂量研究

目的 评估¹⁸F-Choline、¹¹C-Choline和⁶⁸Ga-PSMA PET-CT检查致前列腺癌患者的有效剂量和器官剂量。方法 回顾性研究2017年5月至2018年6月广西医科大学附属肿瘤医院接受PET-CT检查的150例前列腺癌患者,按照注射正电子放射性药物类型分为3组,每组50例。CT定位扫描电压和电流分别为120 kV和35 mA,全身CT扫描电和电流分别为120 kV和（135.6±9.4） mA。PET部分的剂量利用基于医学内照射剂量（MIRD）计算方法的OLINDA/EXM （version 1.1）软件行计算。利用有效剂量转换因子和ImPACT （version 1.0.4） CT剂量计算器计算CT部分剂量,CT剂量指数（CTDI）利用标准体模测量和ImPACT CT计算,组织权重因子取自国际放射防护委员会（ICRP）103号报告,PET和CT剂量之和为患者总有效剂量。结果 注射¹⁸F-Choline、¹¹C-Choline和⁶⁸Ga-PSMA的活度分别为（279.2±13.2）、（350.2±39.9）和（186.8±19.4） MBq,有效剂量分别为（5.0±0.2）、（1.6±0.2）和（3.0±0.3） mSv,差异有统计学意义（F=837.0,P<0.001）。CT有效剂量为（11.4±0.2） mSv。3组总有效剂量分别为（16.4±0.3）、（13.0±0.3）和（14.4±0.4） mSv。PET检查3组器官当量剂量平均值比较,差异有统计学意义（F=381.2~1 637.7,P<0.001）。¹⁸F-Choline和⁶⁸Ga-PSMA PET-CT检查器官当量剂量最高为肾脏,而¹¹C-Choline PET-CT检查最高为甲状腺。结论 PET-CT检查致前列腺癌患者的有效剂量为13.0~16.4 mSv,其中绝大部分的剂量来自CT扫描。¹¹C-Choline PET-CT检查致患者的辐射剂量最低,有望成为潜在的前列腺癌PET显像药物。     

Study on surface dose generated in prostate intensity-modulated radiation therapy treatment

The surface doses of 6- and 15-MV prostate intensity-modulated radiation therapy (IMRT) irradiations were measured and compared to those from a 15-MV prostate 4-beam box (FBB). IMRT plans (step-and-shoot technique) using 5, 7, and 9 beams with 6- and 15-MV photon beams were generated from a Pinnacle treatment planning system (version 6) using computed tomography (CT) scans from a Rando Phantom (ICRU Report 48). Metal oxide semiconductor field effect transistor detectors were used and placed on a transverse contour line along the Phantom surface at the central beam axis in the measurement. Our objectives were to investigate: (1) the contribution of the dynamic multileaf collimator (MLC) to the surface dose during the IMRT irradiation; (2) the effects of photon beam energy and number of beams used in the IMRT plan on the surface dose. The results showed that with the same number of beams used in the IMRT plan, the 6-MV irradiation gave more surface dose than that of 15 MV to the phantom. However, when the number of beams in the plan was increased, the surface dose difference between the above 2 photon energies became less. The average surface dose of the 15-MV IMRT irradiation increased with the number of beams in the plan, from 0.86% to 1.19%. Conversely, for 6 MV, the surface dose decreased from 1.33% to 1.24% as the beam number increased from 7 to 9. Comparing the 15-MV FBB and 6-MV IMRT plans with 2 Gy/fraction, the IMRT irradiations gave generally more surface dose, from 15% to 30%, depending on the number of beams in the plan. It was found that the increase in surface dose for the IMRT technique compared to the FBB plan was predominantly due to the number of beams and the calculated monitor units required to deliver the same dose at the isocenter in the plans. The head variation due to the dynamic MLC movement changing the surface dose distribution on the patient was reflected by the IMRT dose-intensity map. Although prostate IMRT in this study had an average higher surface dose than that of FBB, the more even distribution of relatively lower surface dose in IMRT field could avoid the big dose peaks at the surface positions directly under the FBB fields. Such an even and low surface dose distribution surrounding the patient in IMRT is believed to give less skin complication than that of FBB with the same prescribed dose.     

Study on surface dose generated in prostate intensity-modulated radiation therapy treatment

The surface doses of 6- and 15-MV prostate intensity-modulated radiation therapy (IMRT) irradiations were measured and compared to those from a 15-MV prostate 4-beam box (FBB). IMRT plans (step-and-shoot technique) using 5, 7, and 9 beams with 6- and 15-MV photon beams were generated from a Pinnacle treatment planning system (version 6) using computed tomography (CT) scans from a Rando Phantom (ICRU Report 48). Metal oxide semiconductor field effect transistor detectors were used and placed on a transverse contour line along the Phantom surface at the central beam axis in the measurement. Our objectives were to investigate: (1) the contribution of the dynamic multileaf collimator (MLC) to the surface dose during the IMRT irradiation; (2) the effects of photon beam energy and number of beams used in the IMRT plan on the surface dose. The results showed that with the same number of beams used in the IMRT plan, the 6-MV irradiation gave more surface dose than that of 15 MV to the phantom. However, when the number of beams in the plan was increased, the surface dose difference between the above 2 photon energies became less. The average surface dose of the 15-MV IMRT irradiation increased with the number of beams in the plan, from 0.86% to 1.19%. Conversely, for 6 MV, the surface dose decreased from 1.33% to 1.24% as the beam number increased from 7 to 9. Comparing the 15-MV FBB and 6-MV IMRT plans with 2 Gy/fraction, the IMRT irradiations gave generally more surface dose, from 15% to 30%, depending on the number of beams in the plan. It was found that the increase in surface dose for the IMRT technique compared to the FBB plan was predominantly due to the number of beams and the calculated monitor units required to deliver the same dose at the isocenter in the plans. The head variation due to the dynamic MLC movement changing the surface dose distribution on the patient was reflected by the IMRT dose-intensity map. Although prostate IMRT in this study had an average higher surface dose than that of FBB, the more even distribution of relatively lower surface dose in IMRT field could avoid the big dose peaks at the surface positions directly under the FBB fields. Such an even and low surface dose distribution surrounding the patient in IMRT is believed to give less skin complication than that of FBB with the same prescribed dose.     

Low dose rate brachytherapy for primary treatment of localized prostate cancer: A systemic review and executive summary of an evidence-based consensus statement

PURPOSEThe purpose of this guideline is to present evidence-based consensus recommendations for low dose rate (LDR) permanent seed brachytherapy for the primary treatment of prostate cancer.METHODS AND MATERIALSThe American Brachytherapy Society convened a task force for addressing key questions concerning ultrasound-based LDR prostate brachytherapy for the primary treatment of prostate cancer. A comprehensive literature search was conducted to identify prospective and multi-institutional retrospective studies involving LDR brachytherapy as monotherapy or boost in combination with external beam radiation therapy with or without adjuvant androgen deprivation therapy. Outcomes included disease control, toxicity, and quality of life.RESULTSLDR prostate brachytherapy monotherapy is an appropriate treatment option for low risk and favorable intermediate risk disease. LDR brachytherapy boost in combination with external beam radiation therapy is appropriate for unfavorable intermediate risk and high-risk disease. Androgen deprivation therapy is recommended in unfavorable intermediate risk and high-risk disease. Acceptable radionuclides for LDR brachytherapy include iodine-125, palladium-103, and cesium-131. Although brachytherapy monotherapy is associated with increased urinary obstructive and irritative symptoms that peak within the first 3 months after treatment, the median time toward symptom resolution is approximately 1 year for iodine-125 and 6 months for palladium-103. Such symptoms can be mitigated with short-term use of alpha blockers. Combination therapy is associated with worse urinary, bowel, and sexual symptoms than monotherapy. A prostate specific antigen <= 0.2 ng/mL at 4 years after LDR brachytherapy may be considered a biochemical definition of cure.CONCLUSIONSLDR brachytherapy is a convenient, effective, and well-tolerated treatment for prostate cancer.     

放射性粒子植入的生物有效剂量计算及其临床应用

目的 建立计算放射性粒子植入治疗生物有效剂量（BED）和2 Gy分割生物等效剂量（EQD2）的模型。方法 引入根据L-Q模型建立的外照射BED计算公式和持续低剂量照射BED计算公式。结合BED公式,根据EQD2的定义,建立持续低剂量率照射（放射性粒子植入治疗）的EQD2计算公式。总结常见组织的α/β值和见于文献报道正常组织的T_r1/2值,利用实际值,进一步简化EDQ2计算公式,提出早反应组织和晚反应组织的EDQ2计算经验公式,并命名为王-彭经验公式。对于早反应组织,EQD2≈10D/12（王-彭公式 1）;对于晚反应组织,EQD2≈D/2（王-彭公式 2）。进一步举例说明本文所建立公式在临床上的应用,包括原发性肺癌、食管癌锁骨上淋巴结转移和宫颈癌腹膜后淋巴结转移。结果 根据王-彭经验公式,肿瘤临近的晚反应组织的EQD2仅约为肿瘤组织受量的一半,故而放射性粒子植入治疗"天然地"从生物等效剂量上对晚反应的组织进行了保护。通过实际计算,发现早反应组织的经验公式较为精确,而晚反应组织的经验公式精确度略差,只能做粗略估计。结论 本研究引入的BED计算公式和据此建立的一系列EQD2计算公式以及王-彭经验公式,在理论上可行,可用于放射性粒子植入治疗的物理剂量与外照射剂量之间的换算和叠加。但是使用公式时应谨慎,注意预设条件,慎重解读计算得出的结果。     

Subtotal mastectomy and radiation therapy in the definitive management of localized breast malignancy.

Between 1961 and 1974, 51 women with primary carcinoma of the breast were treated by external radiation following surgery that was limited to diagnostic biopsy. All patients tolerated therapy well with minimal long term morbidity. While the reported follow-up periods are brief (most patients at risk for less than 3 years), 29 patients remain alive, 25 of whom show no evidence of persistent or recurring disease. These data suggest that local-regional control rates match those obtained following mastectomy. Definitive statements as to local failures and long term survival rates are not yet available.     

Favorable preservation of erectile function after prostate brachytherapy for localized prostate cancer

PurposeWe analyzed the rate of preserved potency after prostate brachytherapy (PB) with radioactive seeds and the impact of patient comorbidities on post-PB erectile dysfunction (ED).MethodsWe included 627 patients who were assessed for pre- and postimplant potency between 2005 and 2017. Assessment was based on the Common Terminology Criteria for Adverse Events Scale (CTCAEs). Logistic regression models were used to assess clinical predictors of preserved potency after PB defined as having sufficient erections for sexual activity with or without the need of oral pharmacologic assistance. Covariates included age, diabetes (DM), hypertension (HTN), dyslipidemia (DLP), coronary artery disease (CAD), International Prostate Symptom Score (IPSS), prostate volume, and Cancer of the Prostate Risk Assessments (CAPRA) score. Patients on androgen deprivation therapy or using five alpha reductase inhibitors were excluded from analyses.ResultsPost-PB potency was assessed at an average of 6 months (n = 627), 1 year (n = 538), 2 years (=440), 4 years (n = 272), and 5 years (n = 124). At 2 and 5 years, post-PB potency was preserved in 87% and 84% of patients, respectively. When adjusting for all available covariates, advanced age, pre-PB potency, and the presence of vascular comorbidities (HTN, DM, and DLP) were all predictors of potency at 2 years after PB (all p < 0.01). When performing a sensitivity analysis for vascular comorbidities, the presence of DM had the strongest impact on ED than either HTN or DLP (p < 0.01).ConclusionMore than 84% of patients had preserved potency 5 years after PB. Advanced age, pre-PB potency, and vascular comorbidities had a statistically significant impact on potency after PB.