Total body irradiation for standard treatment rooms: a robust sweeping beam technique with respect to the body shape.

Background: The purpose of this work is to improve a sweeping beam technique for total body irradiation (TBI) on a low flat couch using a varying patient thickness model. We designed a flat couch for total body irradiation in supine and prone position. Three generic arcs with rectangular segments for a patient torso thickness of 16, 22 and 28 cm were generated with respect to varying patient thickness of four particular parts of the body: head, torso, thighs and calves. Materials and methods: Longitudinal and transversal dose profiles were measured using an ionization chamber and the EBT3 gafchromic film in a solid water slab phantom. The robustness of the method was examined in phantoms of different thicknesses. Results: Measured dose homogeneity stays within ±10% of prescribed dose for all of the three patient thickness models. The robustness of the method was evaluated as the increase in dose in the phantom center of 0.7% per 1 cm reduction in phantom thickness. Conclusion: The method is applicable for the broad range of patient sizes, comfortable for patients, robust and suitable for standard treatment rooms with a standard linear accelerator. It requires minimal investments into equipment.

Cardiac doses of accelerated partial breast irradiation with perioperative multicatheter interstitial brachytherapy.

PURPOSE: To quantify mean heart dose (MHD) and doses to the left anterior descending artery (LAD) and left ventricle (LV) in a retrospective series of patients who underwent perioperative accelerated partial breast irradiation with multicatheter interstitial brachytherapy (MIB-APBI). METHODS: Sixty-eight patients with low-risk left breast cancer were treated with MIB-APBI at our institution between 2012 and 2017. Interstitial tubes were inserted during the tumorectomy and sentinel node biopsy and APBI was started 6 days later. The prescribed dose was 34 Gy in 10 fractions (twice a day) to the clinical target volume (CTV). The heart, LAD, and LV were contoured and the distance between each structure and the CTV was measured. The MHD, mean and maximum LAD doses (LAD mean/max), and mean LV doses (LV mean) were calculated and corrected to biologically equivalent doses in 2­Gy fractionation (EQD2). We also evaluated the impact of the distance between the cardiac structures and the CTV and of the volume receiving the prescribed dose (V100) and high-dose volume (V150) on heart dosimetry. RESULTS: Mean EQD2 for MHD, LAD mean/max, and mean LV were 0.9 ± 0.4 Gy (range 0.3-2.2), 1.6 ± 1.1 Gy (range, 0.4-5.6), 2.6 ± 1.9 Gy (range, 0.7-9.2), and 1.3 ± 0.6 Gy (range, 0.5-3.4), respectively. MHD, LAD mean/max, and LV mean significantly correlated with the distance between the CTV and these structures, but all doses were below the recommended limits (German Society of Radiation Oncology; DEGRO). The MHD and LV mean were significantly dependent on V100. CONCLUSION: Perioperative MIB-APBI resulted in low cardiac doses in our study. This finding provides further support for the value of this technique in well-selected patients with early-stage left breast cancer.

Cardiotoxicity of radiation therapy in esophageal cancer.

With a development of radiotherapeutic techniques, availability of radiotherapy data on cardiotoxicity, and slowly improving esophageal cancer outcomes, an increasing emphasis is placed on the heart protection in radiation treated esophageal cancer patients. Radiation induced heart complications encompass mainly pericardial disease, cardiomyopathy, coronary artery atherosclerosis, valvular heart disease, and arrhythmias. The most frequent toxicity is pericardial effusion which is usually asymptomatic in the majority of patients. The use of modern radiotherapy techniques is expected to reduce the risk of cardiotoxicity, although this expectation has to be confirmed by clinical data.

Validation of dose distribution computation on sCT images generated from MRI scans by Philips MRCAT.

AIM: To evaluate calculation of treatment plans based on synthetic-CT (sCT) images generated from MRI. BACKGROUND: Because of better soft tissue contrast, MR images are used in addition to CT images for radiotherapy planning. However, registration of CT and MR images or repositioning between scanning sessions introduce systematic errors, hence suggestions for MRI-only therapy. The lack of information on electron density necessary for dose calculation leads to sCT (synthetic CT) generation. This work presents a comparison of dose distribution calculated on standard CT and sCT. MATERIALS AND METHODS: 10 prostate patients were included in this study. CT and MR images were collected for each patient and then water equivalent (WE) and MRCAT images were generated. The radiation plans were optimized on CT and then recalculated on MRCAT and WE data. 2D gamma analysis was also performed. RESULTS: The mean differences in the majority of investigated DVH points were in order of 1% up to 10%, including both MRCAT and WE dose distributions. Mean gamma pass for acceptance criteria 1%/1 mm were greater than 82.5%. Prescribed doses for target volumes and acceptable doses for organs at risk were met in almost all cases. CONCLUSIONS: The dose calculation accuracy on MRCAT was not significantly compromised in the majority of clinical relevant DVH points. The introduction of MRCAT into practise would eliminate systematic errors, increase patients' comfort and reduce treatment expenses. Institutions interested in MRCAT commissioning must, however, consider changes to established workflow.

Neoadjuvant chemoradiotherapy of rectal carcinoma : Baseline hematologic parameters influencing outcomes.

BACKGROUND: The link between the blood count and a systemic inflammatory response (SIR) is indisputable and well described. Pretreatment hematological parameters may predict the overall clinical outcomes in many types of cancer. Thus, this study aims to systematically evaluate the relationship between baseline blood count levels and treatment response in rectal cancer patients treated with neoadjuvant chemoradiotherapy. PATIENTS AND METHODS: From 2009-2015, 173 patients with locally advanced rectal cancer were retrospectively enrolled in the study and analyzed. The baseline blood count was recorded in all patients 1 week before chemoradiation. Tumor response was evaluated through pathologic findings. Blood count levels which included RBC (red blood cells), Hb (hemoglobin), PLT (platelet count), neutrophil count, WBC (white blood cells), NLR (neutrophil-to-lymphocyte ratio), and PLR (platelet-to-lymphocyte ratio) were analyzed in relation to tumor downstaging, pCR (pathologic complete response), OS (overall survival), and DFS (disease-free survival). RESULTS: Hb levels were associated with a response in logistic regression analysis: pCR (p = 0.05; OR 1.04, 95 % CI 1.00-1.07); T downstaging (p = 0.006; OR 1.03, 95 % CI 1.01-1.05); N downstaging (p = 0.09; OR 1.02, 95 % CI 1.00-1.04); T or N downstaging (p = 0.007; OR 1.04, 95 % CI 1.01-1.07); T and N downstaging (p = 0.02; OR 1.02, 95 % CI 1.00-1.04); Hb and RBC were the most significant parameters influencing OS; PLT was a negative prognostic factor for OS and DFS (p = 0.008 for OS); an NLR value of 2.8 was associated with the greatest significance for OS (p = 0.03) and primary tumor downstaging (p = 0.02). CONCLUSION: Knowledge of pretreatment hematological parameters appears to be an important prognostic factor in patients with rectal carcinoma.

Comparing morbidity and cancer control after 3D-conformal (70/74 Gy) and intensity modulated radiotherapy (78/82 Gy) for prostate cancer.

PURPOSE: The purpose of this work was to compare toxicity and cancer control between patients with prostate cancer treated using three-dimensional conformal radiotherapy (3D-CRT) and those treated using intensity-modulated radiation therapy (IMRT). METHODS AND MATERIALS: A total of 553 patients with prostate cancer were treated with 3D-CRT 70-74 Gy (3D-CRT 70, 3D-CRT 74) or IMRT 78-82 Gy (IMRT 78, IMRT/SIB 82). Late toxicity was scored according to FC-RTOG/LENT criteria. Biochemical failure was defined using the Phoenix and ASTRO definitions. RESULTS: The 5-year risk of grade 2-4 genitourinary toxicity was 26.3 % (3D-CRT 70), 27.2 % (3D-CRT 74), 17.3 % (IMRT 78), and 25.1 % (IMRT/SIB 82) without statistical differences. The 5-year risk of grade 2-4 gastrointestinal toxicity was 19.4 % (3D-CRT 70), 42.1 % (3D-CRT 74), 20.5 % (IMRT 78), and 26.6 % (IMRT/SIB 82). The differences between 3D-CRT 74 and 3D-CRT 70 and between 3D-CRT 74 and IMRT 78 were statistically significant (log rank p = 0.03). The 5-year Phoenix PSA relapse-free survival (PSA-RFS) in low-risk, intermediate-risk, and high-risk patients treated using 3D-CRT were 89.4, 65.5, and 57.8 %, respectively. Patients treated with IMRT achieved the following results: 90.9, 89.4, and 83.9 %. Clinical relapse-free survival (C-RFS) in patients treated using 3D-CRT vs. IMRT for the aforementioned groups were 94.7 vs. 100 %, 86.8 vs. 98.6 %, and 84.4 vs. 94.5 %. Disease-free survival (DFS) for patients treated using 3D-CRT were 83.1, 70.9, and 71.5 %. The IMRT group reached 95.8, 89.1, and 87.6 %. The PSA-RFS for intermediate- and high-risk patients were statistically significant, while C-RFS and DFS were marginally better. CONCLUSION: Dose escalation with IMRT was associated with improved cancer control in intermediate- and high-risk patients in comparison with 3D-CRT, without compromising toxicity.

Utilization of cone beam CT for reconstruction of dose distribution delivered in image-guided radiotherapy of prostate carcinoma - bony landmark setup compared to fiducial markers setup.

The purpose of this study was to compare two different styles of prostate IGRT: bony landmark (BL) setup vs. fiducial markers (FM) setup. Twenty-nine prostate patients were treated with daily BL setup and 30 patients with daily FM setup. Delivered dose distribution was reconstructed on cone-beam CT (CBCT) acquired once a week immediately after the alignment. Target dose coverage was evaluated by the proportion of the CTV encompassed by the 95% isodose. Original plans employed 1 cm safety margin. Alternative plans assuming smaller 7 mm margin between CTV and PTV were evaluated in the same way. Rectal and bladder volumes were compared with initial ones. While the margin reduction in case of BL setup makes the prostate coverage significantly worse (p = 0.0003, McNemar's test), in case of FM setup with the reduced 7 mm margin, the prostate coverage is even better compared to BL setup with 10 mm margin (p = 0.049, Fisher's exact test). Moreover, partial volumes of organs at risk irradiated with a specific dose can be significantly lowered (p < 0.0001, unpaired t-test). Reducing of safety margin is not acceptable in case of BL setup, while the margin can be lowered from 10 mm to 7 mm in case of FM setup.

High-dose-rate brachytherapy at 3 Gy per fraction for lip carcinoma: Treatment outcomes and toxicity at 5-years.

PURPOSE: Low-dose-rate brachytherapy (LDR-BT) is a well-established treatment for lip cancer. High-dose-rate (HDR)-BT is a promising alternative to LDR-BT, but data are limited. In this context, we retrospectively evaluated treatment outcomes in a series of patients who underwent HDR-BT for lip carcinoma between 2003 and 2021. MATERIALS AND METHODS: A total of 32 patients were included in this study, with a median age of 73.5 years (range, 61 - 88). The indications for HDR-BT were as follows: primary treatment (n = 17), adjuvant treatment (n = 3), and recurrent disease after surgery (n = 12). The prescribed dose was 18 fractions of 3 Gy administered twice daily. RESULTS: At a median followup of 45 months (range, 12 -232), the 5-year local recurrence-free interval was 96.9% (95% CI: 90.9-100%), the disease-free interval was 85% (95% CI: 70.9-99.1), and 5-year overall survival was 64.7% (95% CI: 44.7-84.8). Eleven patients died, all on age related comorbidities. Acute toxicity manifested as G1 dry desquamation in 6 patients (18.8%), G2 erythema in 10 patients (31.2%) and G3 confluent moist desquamation in 16 patients (50%). Late complications included G1 fibrosis (100% of cases). G1 and G2 depigmentation was observed in 8 (25%) and 6 (18%) patients, G1 telangiectasia occurred in 5 patients (16%). CONCLUSIONS: These data support the use of HDR-BT for lip cancer. The dose and fractionation schedule used in this study (18 fractions x 3 Gy twice daily) seems to be effective and safe.

Utilization of cone-beam CT for offline evaluation of target volume coverage during prostate image-guided radiotherapy based on bony anatomy alignment.

AIM: To assess target volume coverage during prostate image-guided radiotherapy based on bony anatomy alignment and to assess possibility of safety margin reduction. BACKGROUND: Implementation of IGRT should influence safety margins. Utilization of cone-beam CT provides current 3D anatomic information directly in irradiation position. Such information enables reconstruction of the actual dose distribution. MATERIALS AND METHODS: Seventeen prostate patients were treated with daily bony anatomy image-guidance. Cone-beam CT (CBCT) scans were acquired once a week immediately after bony anatomy alignment. After the prostate, seminal vesicles, rectum and bladder were contoured, the delivered dose distribution was reconstructed. Target dose coverage was evaluated by the proportion of the CTV encompassed by the 95% isodose. Original plans employed a 1 cm safety margin. Alternative plans assuming a smaller 7 mm margin between CTV and PTV were evaluated in the same way. Rectal and bladder volumes were compared with the initial ones. Rectal and bladder volumes irradiated with doses higher than 75 Gy, 70 Gy, 60 Gy, 50 Gy and 40 Gy were analyzed. RESULTS: In 12% of reconstructed plans the prostate coverage was not sufficient. The prostate underdosage was observed in 5 patients. Coverage of seminal vesicles was not satisfactory in 3% of plans. Most of the target underdosage corresponded to excessive rectal or bladder filling. Evaluation of alternative plans assuming a smaller 7 mm margin revealed 22% and 11% of plans where prostate and seminal vesicles coverage, respectively, was compromised. These were distributed over 8 and 7 patients, respectively. CONCLUSION: Sufficient dose coverage of target volumes was not achieved for all patients. Reducing of safety margin is not acceptable. Initial rectal and bladder volumes cannot be considered representative for subsequent treatment.

High-Dose-Rate Brachytherapy as an Organ-Sparing Treatment for Early Penile Cancer.

BACKGROUND: Low-dose-rate brachytherapy is an effective organ-sparing treatment for patients with early-stage penile cancer. However, only limited data are available on the role of high-dose-rate brachytherapy (HDR-BT) in this clinical setting. METHODS: Between 2002 and 2020, 31 patients with early penile cancer were treated at our center with interstitial HDR BT at a dose of 18 × 3 Gy twice daily. A breast brachytherapy template was used for the fixation of stainless hollow needles. RESULTS: The median follow-up was 117.5 months (range, 5-210). Eight patients (25.8%) developed a recurrence; of these, seven were salvaged by partial amputation. Six patients died of internal comorbidities or a second cancer. The probability of local control at 5 and 10 years was 80.7% (95% CI: 63.7-97.7%) and 68.3% (95% CI: 44.0-92.6%), respectively. Cause-specific survival was 100%. Only one case of radiation-induced necrosis was observed. The probability of penile sparing at 5 and 10 years was 80.6% (95% CI: 63.45-97.7%) and 62.1% (95% CI: 34.8-89.4%), respectively. CONCLUSIONS: These results show that HDR-BT for penile cancer can achieve results comparable to LDR-BT with organ sparing. Despite the relatively large patient cohort-the second largest reported to date in this clinical setting-prospective data from larger samples are needed to confirm the role of HDR-BT in penile cancer.

Intensity-modulated radiotherapy in the treatment of subhepatic carcinomas.

BACKGROUND/AIMS: The aim of our study was to evaluate preliminary results of intensity modulated radiotherapy (IMRT) in patients with inoperable subhepatic tumors. METHODOLOGY: Thirteen patients with inoperable cholangiocarcinoma or gall bladder carcinoma were treated by biliary drainage and intensity modulated radiotherapy. In patients with tumors limited to the biliary duct only tumor stenosis was irradiated to the dose of 50-60 Gy. In patients with bulky extraductal tumors the dose was 50 Gy/25 fractions to the whole tumor and an integrated boost was used to raise the dose to the malignant stenosis to 60 Gy/25 fractions. RESULTS: Doses to organs at risk (duodenum, small intestine, liver) were in tolerable limits. In four patients transient fever occurred; one patient had duodenal bleeding that resolved after conservative treatment. Recurrent dilatation of the biliary tract was observed in 4 patients and was managed by exchange of the internal biliary drainage. Median survival was 10.4 months, 5 patients survived for more than one year following diagnosis. CONCLUSIONS: IMRT of inoperable extrahepatic biliary tract tumors allows application of high doses of radiation to the tumor with effective sparing of healthy tissues. The control of jaundice is good. In selected cases IMRT may prolong overall survival.

Daily prostate volume and position monitoring using implanted gold markers and on-board imaging during radiotherapy.

PURPOSE: This study aimed to evaluate prostate volume changes and prostate motions during radiotherapy. METHODS: In 2010, twenty-five patients were treated for prostate cancer by external beam radiotherapy with implanted fiducial markers. Coordinates of three gold markers on kilovoltage images were calculated daily. Volume changes in target structure were observed through changes in intermarker distances. Differences in patient position between laser-tattoo alignment and gold marker localization were evaluated. Intrafraction motion was assessed by measuring marker displacement on kilovoltage images acquired before and after fraction delivery. RESULTS: Prostate shrinkage was observed in 60% of patients. The average shrinkage was 7% of the prostate's initial volume. Corrections after laser-tattoo alignment remained mostly below 1 cm. The difference between marker centroid position on the actual images and the planning images was 2 +/- 1 mm on average. The extension of intrafraction movements was 7.6 +/- 0.2 mm on average. CONCLUSIONS: In our retrospective study, the possibility for prostate volume changes during radiotherapy was revealed. Intrafraction movements turned out to be the limiting factor in safety margin reduction.

Hyperfractionated high-dose rate brachytherapy in the treatment of oral tongue cancer.

BACKGROUND: Low-dose rate brachytherapy is a well established treatment modality of oral cancer. Data about high-dose rate (HDR) brachytherapy are still sparse with various fractionation schedules and heterogeneous results. AIM: The aim of our retrospective study was to evaluate the results of HDR brachytherapy with doses of 3 Gy twice daily. PATIENTS AND METHODS: Twenty patients with squamous cell tongue cancer were treated in the years 2001-2009 by exclusive HDR BT 18 × 3 Gy twice daily. The plastic tube technique was used. Median follow up was 47 months (7.8-118) since brachytherapy. RESULTS: The local and locoregional control was 85% and 68%, respectively. Bone necrosis developed in one case treated without mandibular shielding and soft tissue necrosis in 2 cases. CONCLUSION: It can be concluded that HDR brachytherapy with 18 × 3 Gy twice daily is safe with promising local control. The risk of nodal recurrences is substantial.

Perioperative hyperfractionated high-dose rate brachytherapy for the treatment of soft tissue sarcomas: multicentric experience.

BACKGROUND: Low-dose rate brachytherapy is a well-established adjuvant treatment for soft tissue sarcomas (STS). The experience with high-dose rate brachytherapy (HDR BT) in this indication is limited. The purpose of our study was to evaluate the viability of perioperative hyperfractionated HDR BT for STS. METHODS: Forty-five patients with primary (17 cases) or recurrent (28 cases) STS were treated with resection and HDR BT between 1998 and 2007. Eleven patients were treated with HDR BT alone (mean dose 40 Gy; 30-54 Gy) and 34 were treated with a combination of HDR BT (mean dose 24 Gy; 15-30 Gy) and external beam radiotherapy (EBRT) (40-50 Gy). Hyperfractionation, 3 Gy twice daily, was used for HDR BT with plastic tubes. Adjuvant chemotherapy was indicated for patients with high risk of dissemination. RESULTS: Local control (LC) was achieved in 17 patients (100%) treated for primary tumor and in 18 of 28 patients (64%) treated for recurrence; this difference was statistically significant (p = 0.004). Distant metastases occurred in seven patients (15.6%). The 5-year overall survival was 70%; the 5-year local control was 74%. LC was significantly better for extremities sarcomas in comparison with trunk tumors, for patients treated with EBRT and BT in comparison with BT alone, and for doses >65 Gy. CONCLUSIONS: Our study suggests that perioperative HDR BT is a promising method for achieving high biological doses with good LC in the postoperative radiotherapy of STS and that combination of BT and EBRT provides better tumor control than BT alone.

Dose escalation in prostate radiotherapy up to 82 Gy using simultaneous integrated boost: direct comparison of acute and late toxicity with 3D-CRT 74 Gy and IMRT 78 Gy.

PURPOSE: To compare acute and late toxicity after three-dimensional conformal radiotherapy to the prostate to 74 Gy (3D-CRT) with intensity-modulated radiotherapy to 78 Gy (IMRT 78) and IMRT using simultaneous integrated boost to 82 Gy (IMRT/SIB 82). PATIENTS AND METHODS: 94 patients treated with 3D-CRT to the prostate and base of seminal vesicles to 74 Gy represented the first group. The second group consisted of 138 patients subjected to IMRT covering the prostate and base of seminal vesicles to 78 Gy. The last group was treated with IMRT using SIB. The prescribed doses were 82 Gy and 73.8 Gy in 42 fractions to the prostate and seminal vesicles. Late toxicity was prospectively scored according to the RTOG/FC-LENT scale. RESULTS: Acute gastrointestinal toxicity >or= grade 2 occurred in 35.1% of patients treated with 3D-CRT, in 16% subjected to IMRT 78, and in 7.7% receiving IMRT/SIB 82. Acute genitourinary toxicity >or= grade 2 was observed in 26.6% (3D-CRT), 33% (IMRT 78), and 30.7% (IMRT/SIB 82). At 3 years, the estimated cumulative incidence of grade 3 late gastrointestinal toxicity was 14% for 3D-CRT, 5% for IMRT 78, and 2% for IMRT/SIB 82. The difference became significant (log rank p = 0.02). The estimated cumulative incidence of grade 3 late genitourinary toxicity was 9% (3D-CRT), 7% (IMRT 78), and 6% (IMRT/SIB 82) without statistical differences (log rank p = 0.32) CONCLUSION: SIB enables dose escalation up to 82 Gy with a lower rate of gastrointestinal toxicity grade 3 in comparison with 3D-CRT up to 74 Gy.

Late toxicity after conformal and intensity-modulated radiation therapy for prostate cancer: impact of previous surgery for benign prostatic hyperplasia.

OBJECTIVES: To retrospectively compare late toxicity of conventional-dose three-dimensional conformal radiation therapy (3D-CRT) and high-dose intensity-modulated radiation therapy (IMRT) for prostate cancer. METHODS: A total of 340 patients with T1-3 prostate cancer were treated with 3D-CRT (n = 228) and IMRT (n = 112). The median follow-up time was 5.9 years and 3.0 years, respectively. The prescription dose was 70 Gy for 3D-CRT and 78 Gy for IMRT. Late gastrointestinal (GI) and genitourinary (GU) toxicities were graded according to the Fox Chase modification of the Radiation Therapy Oncology Group and Late Effects Normal Tissue Task Force criteria. RESULTS: There was no difference between 3D-CRT and IMRT in the incidence of GI and GU toxicity at 3 years. On multivariate analysis, transurethral resection of prostate/open transvesical prostatectomy (TURP/TVPE) for benign prostatic hyperplasia, carried out before radiotherapy, significantly increased the risk of Grade >or=2 GU toxicity (risk ratio 1.88). Among patients who experienced TURP/TVPE, the 5-year actuarial likelihood of Grade 2-3 urinary incontinence was 23%, compared with 9% for those without prostate surgery (P = 0.01). CONCLUSIONS: Tolerance of 3D-CRT and IMRT was similar, despite the use of high radiation dose with IMRT. Previous TURP/TVPE increased the risk of GU toxicity.

Accelerated partial breast irradiation in elderly breast cancer patients.

Breast-conserving surgery with adjuvant whole-breast irradiation has become the standard treatment for early breast cancer (EBC) patients. Partial breast irradiation, which targets only the postoperative cavity, has been established as an alternative to whole-breast therapy in selected patients. The treatment of elderly breast cancer patients differs from the therapeutic approach in younger ones, as elderly patients are prone to geriatric frailty and comorbid conditions, the incidence and severity of which increase with age. A review of the evidence, process, techniques, and results of accelerated partial breast irradiation (APBI) in elderly EBC patients, seems to indicate that APBI is an advisable postoperative approach in properly selected elderly EBC patients, combining advantages of a radical approach that minimizes the risk of undertreatment with efficient reduction of redundant irradiated volume, treatment toxicity, overall treatment time, staff workload, radiation technique workflow, patient transportation, and the potential for non-compliance. There is no "one size fits all" technique of APBI, the best technique always depending on willing patients, individual anatomy, performance status, patient frailty and comorbid conditions, and tumour location.

The Time Between Chemoradiation and Surgery for Rectal Carcinoma Negatively Influences Mesorectal Excision Quality.

Total mesorectal excision quality (TMEq) is a prognostic factor associated with local recurrence in rectal adenocarcinoma. Neoadjuvant chemoradiotherapy (NCRT) reduces the risk of tumor recurrence, but may compromise TMEq. The time between NCRT and surgery (TTS) and how it influences TMEq and tumor control were evaluated. In prospective registry, 236 patients after NCRT and TME were analyzed. NCRT involved radiotherapy with 45 Gy to the pelvis, plus tumor boost dose 5.4 Gy with concurrent 5-fluorouracil infusion. NCRT was followed by TME after 9 weeks on average (median 9.4 ± SD 2.5). TMEq was parametrically analyzed by standard three-grade system. With median follow-up of 47.5 months, 3-year overall survival (OS) was 83.8%, disease-free survival (DFS) was 77.7%, and 6.4% was the rate of local recurrence (LR). TTS was not associated with OS, DFS, or LR. TMEq was found to be associated with LR in univariate analysis, but not in multivariate, where pathological tumor stage and resection margins remained dominant predictors. TMEq was negatively influenced by inferior location of the tumor, longer TTS, higher tumor and nodal stage, presence of tumor perforation, perineural invasion, and close/positive resection margins. Nonetheless, TTS remained a strong predictor of TMEq in multivariate analyses. TTS was proven to be an independent predictor of TMEq. With longer TTS, fewer complete TME with intact mesorectal plane were observed. However, TTS was not associated with survival deterioration or tumor recurrence. These were negatively influenced by other factors interfering with TMEq, especially by pathological tumor stage and resection margins.