Tolerance of normal tissue to therapeutic irradiation

Prostate-Specific Membrane Antigen Radioligand Therapy Using 177Lu-PSMA I&T and 177Lu-PSMA-617 in Patients with Metastatic Castration-Resistant Prostate Cancer: Comparison of Safety, Biodistribution, and Dosimetry

The objective of this study was to determine the safety, kinetics, and dosimetry of the ¹⁷⁷Lu-labeled prostate-specific membrane antigen (PSMA) small molecules ¹⁷⁷Lu-PSMA I&T and ¹⁷⁷Lu-PSMA-617 in a large cohort of patients with metastatic castration-resistant prostate cancer (mCRPC) undergoing PSMA radioligand therapy (PRLT). Methods: In total, 138 patients (mean age, 70 ± 9 y; age range, 46-90 y) with progressive mCRPC and PSMA expression verified by ⁶⁸Ga-PSMA-11 PET/CT underwent PRLT. Fifty-one patients received 6.1 ± 1.0 GBq (range, 3.4-7.6 GBq) of ¹⁷⁷Lu-PSMA I&T, and 87 patients received 6.5 ± 1.1 GBq (range, 3.5-9.0 GBq) of ¹⁷⁷Lu-PSMA-617. Dosimetry was performed on all patients using an identical protocol. The mean absorbed doses were estimated with OLINDA software (MIRD Scheme). Treatment-related adverse events were graded according to the Common Terminology Criteria for Adverse Events, version 5.0, of the National Cancer Institute. Results: The whole-body half-lives were shorter for ¹⁷⁷Lu-PSMA I&T (35 h) than for ¹⁷⁷Lu-PSMA-617 (42 h). The mean whole-body dose of ¹⁷⁷Lu-PSMA-617 was higher than that of ¹⁷⁷Lu-PSMA I&T (0.04 vs. 0.03 Gy/GBq, P < 0.00001). Despite the longer half-life of ¹⁷⁷Lu-PSMA-617, the renal dose was lower for ¹⁷⁷Lu-PSMA-617 than for ¹⁷⁷Lu-PSMA I&T (0.77 vs. 0.92 Gy/GBq, P = 0.0015). Both PSMA small molecules demonstrated a comparable dose to the parotid glands (0.5 Gy/GBq, P = 0.27). Among all normal organs, the lacrimal glands exhibited the highest mean absorbed doses, 5.1 and 3.7 Gy/GBq, for ¹⁷⁷Lu-PSMA-617 and ¹⁷⁷Lu-PSMA I&T, respectively. All tumor metastases exhibited a higher initial uptake when using ¹⁷⁷Lu-PSMA I&T than when using ¹⁷⁷Lu-PSMA-617, as well as a shorter tumor half-life (P < 0.00001). The mean absorbed tumor doses were comparable for both ¹⁷⁷Lu-PSMA I&T and ¹⁷⁷Lu-PSMA-617 (5.8 vs. 5.9 Gy/GBq, P = 0.96). All patients tolerated the therapy without any acute adverse effects. After ¹⁷⁷Lu-PSMA-617 and ¹⁷⁷Lu-PSMA I&T, there was a small, statistically significant reduction in hemoglobin, leukocyte counts, and platelet counts that did not need any clinical intervention. No nephrotoxicity was observed after either ¹⁷⁷Lu-PSMA I&T or ¹⁷⁷Lu-PSMA-617 PRLT. Conclusion: Both ¹⁷⁷Lu-PSMA I&T and ¹⁷⁷Lu-PSMA-617 PRLT demonstrated favorable safety in mCRPC patients. The highest absorbed doses among healthy organs were in the lacrimal and parotid glands-not, however, resulting in any significant clinical sequel. ¹⁷⁷Lu-PSMA-617 demonstrated a higher absorbed dose to the whole-body and lacrimal glands but a lower renal dose than did ¹⁷⁷Lu-PSMA I&T. The mean absorbed tumor doses were comparable for both ¹⁷⁷Lu-PSMA I&T and ¹⁷⁷Lu-PSMA-617. There was a large interpatient variability in the dosimetry parameters. Therefore, individual patient-based dosimetry seems favorable for personalized PRLT.

Comparison of Breast Cancer Radiotherapy Techniques Regarding Secondary Cancer Risk and Normal Tissue Complication Probability - Modelling and Measurements Using a 3D-Printed Phantom

Background

Radiotherapy after breast-conserving therapy is a standard postoperative treatment of breast cancer, which can be carried out with a variety of irradiation techniques. The treatment planning must take into consideration detrimental effects on the neighbouring organs at risk-the lung, the heart, and the contralateral breast, which can include both short- and long-term effects represented by the normal tissue complication probability and secondary cancer risk.

Patients and Methods

In this planning study, we investigate intensity-modulated (IMRT) and three-dimensional conformal (3D-CRT) radiotherapy techniques including sequential or simultaneously integrated boosts as well as interstitial multicatheter brachytherapy boost techniques of 38 patients with breast-conserving surgery retrospectively. We furthermore develop a 3D-printed breast phantom add-on to allow for catheter placement and to measure the out-of-field dose using thermoluminescent dosimeters placed inside an anthropomorphic phantom. Finally, we estimate normal tissue complication probabilities using the Lyman-Kutcher-Burman model and secondary cancer risks using the linear non-threshold model (out-of-field) and the model by Schneider et al. (in-field).

Results

The results depend on the combination of primary whole-breast irradiation and boost technique. The normal tissue complication probabilities for various endpoints are of the following order: 1%-2% (symptomatic pneumonitis, ipsilateral lung), 2%-3% (symptomatic pneumonitis, whole lung), and 1%-2% (radiation pneumonitis grade ≥ 2, whole lung). The additional relative risk of ischemic heart disease ranges from +25% to +35%. In-field secondary cancer risk of the ipsilateral lung in left-sided treatment is around 50 per 10,000 person-years for 20 years after exposure at age 55. Out-of-field estimation of secondary cancer risk results in approximately 5 per 10,000 person-years each for the contralateral lung and breast.

Conclusions

In general, 3D-CRT shows the best risk reduction in contrast to IMRT. Regarding the boost concepts, brachytherapy is the most effective method in order to minimise normal tissue complication probability and secondary cancer risk compared to teletherapy boost concepts. Hence, the 3D-CRT technique in combination with an interstitial multicatheter brachytherapy boost is most suitable in terms of risk avoidance for treating breast cancer with techniques including boost concepts.

The incidence of brainstem toxicity following high-dose conformal proton therapy for adult skull-base malignancies

BACKGROUND

Dose escalation for skull-based malignancies often presents risks to critical adjacent neural structures, including the brainstem. We report the incidence of brainstem toxicity following fractionated high-dose conformal proton therapy and associated dosimetric parameters.

MATERIAL AND METHODS

We performed a single-institution review of patients with skull-base chordoma or chondrosarcoma who were treated with proton therapy between February 2007 and January 2020 on a prospective outcomes-tracking protocol. The primary endpoint was grade ≥2 brainstem toxicity. No patients received concurrent chemotherapy, and brainstem toxicity was censored for analysis if it coincided with local disease progression.

RESULTS

We analyzed 163 patients who received a minimum of 45 GyRBE to 0.03 cm³ of the brainstem. Patients were treated to a median total dose of 73.8 (range 64.5-74.4) GyRBE at 1.8 GyRBE per fraction with 17 patients undergoing twice-daily treatment at 1.2 GyRBE per fraction. With a median follow-up of 4 years, the 5-year cumulative incidence of grade ≥2 brainstem injury was 1.3% (95% CI 0.25-4.3%). There was one grade 2, one grade 3, and no grade 4 or 5 events, with all patients recovering function with medical management.

CONCLUSION

In delivering curative-intent radiotherapy for skull-base chordoma and chondrosarcoma in adults, small volumes of the brainstem can safely receive at least 64 GyRBE with minimal risk of serious brainstem injury.

Radiation-Induced Esophageal Cancer: Investigating the Pathogenesis, Management, and Prognosis

One of the most serious late side effects of irradiation is the promotion of tumorigenesis. Radiation-induced esophageal cancer (RIEC) can arise in a previously irradiated field, mostly in patients previously irradiated for thoracic malignancies such as breast cancer, Hodgkin and non-Hodgkin lymphomas, head and neck cancers, lung cancer, or previous esophageal cancer. RIEC is rare and accounts for less than 1% of all carcinomas of the esophagus. There are little data available in the current literature regarding pathogenesis, diagnosis, treatment, and outcome of esophageal cancer developed in a previously irradiated field. RIEC seems to represent a biologically aggressive disease with a poor prognosis. Although it is difficult to perform radical surgery on a previously irradiated field, R0 resection remains the mainstay of treatment. The use of neoadjuvant and adjuvant chemoradiotherapy remains very helpful in RIEC, similarly to conventional esophageal cancer protocols. The aim of this article is to elucidate this rare but challenging entity.

Assessment of dose perturbations for metal stent in photon and proton radiotherapy plans for hepatocellular carcinoma

BACKGROUND

The present study aimed to investigate the dosimetric impact of metal stent for photon and proton treatment plans in hepatocellular carcinoma.

METHODS

With computed tomography data of a water-equivalent solid phantom, dose perturbation caused by a metal stent included in the photon and proton treatment of hepatocellular carcinoma was evaluated by comparing Eclipse and RayStation treatment planning system (TPS) to a Monte Carlo (MC) based dose calculator. Photon and proton plans were created with anterior-posterior/posterior-anterior (AP/PA) fields using a 6 MV beam and AP/PA fields of a wobbling beam using 150 MeV and a 10 cm ridge filter. The difference in dose distributions and dosimetric parameters were compared depending on the stent's positions (the bile duct (GB) and intestinal tract (GI)) and angles (0°, 45°, and 90°). Additionally, the dose variation in the target volume including the stent was comparatively evaluated through dose volume histogram (DVH) analysis. And the comparison of clinical cases was carried out in the same way.

RESULTS

Percentage differences in the dosimetric parameters calculated by MC ranged from - 7.0 to 3.9% for the photon plan and - 33.7 to 4.3% for the proton plan, depending on the angle at which the GB and GI stents were placed, compared to those without the stent. The maximum difference was observed at the minimum dose (D_min), which was observed in both photon and proton plans in the GB and GI stents deployed at a 90° incidence angle. The parameter differences were greater in the proton plan than in photon plan. The target volume showed various dose variations depending on positions and angles of stent for both beams. Compared with no-stent, the doses within the target volume containing the GI and GB stents for the photon beam were overestimated in the high-dose area at 0°, nearly equal within 1% at 45°, and underestimated at 90°. These doses to the proton beam were underestimated at all angles, and the amount of underdose to the target volume increased with an increase in the stent angle. However, the difference was significantly greater with the proton plan than the photon plan.

CONCLUSIONS

Dose perturbations within the target volume due to the presence of the metal stent were not observed in the TPS calculations for photon and proton beams, but MC was used to confirm that there are dose variations within the target volume. The MC results found that delivery of the treatment beam avoiding the stent was the best method to prevent target volume underdose.

Response Evaluation Following Radiation Therapy With 18F-FDG PET/CT: Common Variants of Radiation-Induced Changes and Potential Pitfalls

Radiation therapy (RT) is one of the cornerstones in cancer treatment and approximately half of all patients will receive some form of RT during the course of their cancer management. Response evaluation after RT and follow-up imaging with ¹⁸F-Fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) can be complicated by RT-induced acute, chronic or consequential effects. There is a general consensus that ¹⁸F-FDG PET/CT for response evaluation should be delayed for 12 weeks after completing RT to minimize the risk of false-positive findings. Radiation-induced late side effects in normal tissue can take years to develop and eventually cause symptoms that on imaging can potentially mimic recurrent disease. Imaging findings in radiation induced injuries depend on the normal tissue included in the irradiated volume and the radiation therapy regime including the total dose delivered, dose per fraction and treatment schedule. The intent for radiation therapy should be taken in consideration when evaluating the response on imaging, that is palliative vs curative or neoadjuvant vs adjuvant RT. Imaging findings can further be distorted by altered anatomy and sequelae following surgery within the radiation field. An awareness of common PET/CT-induced changes/injuries is essential when interpreting ¹⁸F-FDG PET/CT as well as obtaining a complete medical history, as patients are occasionally scanned for an unrelated cause to previously RT treated malignancy. In addition, secondary malignancies due to carcinogenic effects of radiation exposure in long-term cancer survivors should not be overlooked. ¹⁸F-FDG PET/CT can be very useful in response evaluation and follow-up in patients treated with RT, however, variants and pitfalls are common and it is important to remember that radiation-induced injury is often a diagnosis of exclusion.

Delta-like ligand 3-targeted radioimmunotherapy for neuroendocrine prostate cancer

Neuroendocrine prostate cancer (NEPC) is a lethal subtype of prostate cancer with limited meaningful treatment options. NEPC lesions uniquely express delta-like ligand 3 (DLL3) on their cell surface. Taking advantage of DLL3 overexpression, we developed and evaluated lutetium-177 (177Lu)-labeled DLL3-targeting antibody SC16 (177Lu-DTPA-SC16) as a treatment for NEPC. SC16 was functionalized with DTPA-CHX-A" chelator and radiolabeled with 177Lu to produce 177Lu-DTPA-SC16. Specificity and selectivity of 177Lu-DTPA-SC16 were evaluated in vitro and in vivo using NCI-H660 (NEPC, DLL3-positive) and DU145 (adenocarcinoma, DLL3-negative) cells and xenografts. Dose-dependent treatment efficacy and specificity of 177Lu-DTPA-SC16 radionuclide therapy were evaluated in H660 and DU145 xenograft-bearing mice. Safety of the agent was assessed by monitoring hematologic parameters. 177Lu-DTPA-SC16 showed high tumor uptake and specificity in H660 xenografts, with minimal uptake in DU145 xenografts. At all three tested doses of 177Lu-DTPA-SC16 (4.63, 9.25, and 27.75 MBq/mouse), complete responses were observed in H660-bearing mice; 9.25 and 27.75 MBq/mouse doses were curative. Even the lowest tested dose proved curative in five (63%) of eight mice, and recurring tumors could be successfully re-treated at the same dose to achieve complete responses. In DU145 xenografts, 177Lu-DTPA-SC16 therapy did not inhibit tumor growth. Platelets and hematocrit transiently dropped, reaching nadir at 2 to 3 wk. This was out of range only in the highest-dose cohort and quickly recovered to normal range by week 4. Weight loss was observed only in the highest-dose cohort. Therefore, our data demonstrate that 177Lu-DTPA-SC16 is a potent and safe radioimmunotherapeutic agent for testing in humans with NEPC.

Integra Dermal Regeneration Template in reconstructive surgery for cutaneous tumours: a two-year retrospective review

OBJECTIVE

Integra Dermal Regeneration Template (IDRT) (Integra LifeSciences, US) is a bioengineered dermal matrix that has been widely used in burn reconstruction since its first description. However, little is reported on its use in oncologic dermatological defects. Our objective was to evaluate reconstruction using IDRT on cutaneous tumour defects.

METHOD

We conducted a two-year retrospective review of patients with skin tumours who had an excision surgery, followed by reconstruction with IDRT, as a mid-step towards a final autograft procedure: a split-thickness skin graft. The records of all patients at a single academic institution were queried from the electronic medical record using data obtained from the operating surgeon.

RESULTS

We identified 13 patients with different tumour types and locations. The mean defect size was 105.92cm². The matrix take rate was 92.3% and average postoperative day for definite autograft was 20 days. Patients were followed for a period of up to 12 months. Of the patients, one had exposed bone without periosteum; another patient showed recurrence six months after matrix placement, requiring a new second two-stage IDRT-autograft procedure before radiation therapy. Patients reported complete satisfaction with the cosmetic, functional and oncological results. No cases of infection were encountered.

CONCLUSION

IDRT is a valid option for the reconstruction of oncologic surgical defects of the skin and can be used in different anatomical locations. Specifically, it is an alternative to the reconstructive ladder when grafts and local flaps are not possible in those patients, and an option for patients who will eventually need adjuvant radiotherapy.

Dosimetric Parameters Related to Acute Radiation Dermatitis of Patients with Nasopharyngeal Carcinoma Treated by Intensity-Modulated Proton Therapy

Background: Growing patients with nasopharyngeal carcinoma (NPC) were treated with intensity-modulated proton therapy (IMPT). However, a high probability of severe acute radiation dermatitis (ARD) was observed. The objective of the study is to investigate the dosimetric parameters related to ARD for NPC patients treated with IMPT. Methods: Sixty-two patients with newly diagnosed NPC were analyzed. The ARD was recorded based on the criteria of Common Terminology Criteria for Adverse Events version 4.0. Logistic regression model was performed to identify the clinical and dosimetric parameters related to ARD. Receiver operating characteristic (ROC) curve analysis and the area under the curve (AUC) were used to evaluate the performance of the models. Results: The maximum ARD grade was 1, 2, and 3 in 27 (43.5%), 26 (42.0%), and 9 (14.5%) of the patients, respectively. Statistically significant differences (p < 0.01) in average volume to skin 5 mm with the respective doses were observed in the range 54−62 Cobalt Gray Equivalent (CGE) for grade 2 and 3 versus grade 1 ARD. Smoking habit and N2-N3 status were identified as significant predictors to develop grade 2 and 3 ARD in clinical model, and V58CGE to skin 5 mm as an independent predictor in dosimetric model. After adding the variable of V58CGE to the metric incorporating two parameters of smoking habit and N status, the AUC value of the metric increases from 0.78 (0.66−0.90) to 0.82 (0.72−0.93). The most appropriate cut-off value of V58CGE to skin 5 mm as determined by ROC curve was 5.0 cm3, with a predicted probability of 54% to develop grade 2 and 3 ARD. Conclusion: The dosimetric parameter of V58CGE to skin 5 mm < 5.0 cm3 could be used as a constraint in treatment planning for NPC patients treated by IMPT.

Is a single late SPECT/CT based kidney 177Lu-dosimetry superior to hybrid dosimetry with sequential multiple time-point whole-body planar scans in combination with an early SPECT/CT?

PURPOSE

The aim is to assess the impact of different imaging-protocols on image-based kidney dosimetry in ¹⁷⁷Lu labelled peptide receptor radiotherapies.

METHODS

Kidney data of five [¹⁷⁷Lu]Lu-OPS201 injected pigs and a 3D printed phantom were used for comparing the absorbed doses and time-integrated activity coefficients calculated based on the following imaging-protocols: A-) multiple time-point SPECT/CTs, B-) multiple time-point planar scans in combination with one SPECT/CT, C-) single time-point SPECT/CT. In addition, the influence of late scan time-points on kidney dosimetry was investigated by sequentially eliminating scan data at > 100 h from the pig/phantom datasets for imaging-protocols A and B.

RESULTS

Compared to imaging-protocol A, absorbed doses based on imaging-protocols B and C (scans at > 24 h post-injection) were always lower (differences > 34%). The best agreement in absorbed dose was achieved by imaging-protocol C at ∼ 100 h post-injection (difference: 4%). Regarding the phantom/pig experiments, eliminating scan data at > 100 h post-injection increased the time-integrated activity coefficients calculated based on imaging-protocols A and B by up to 83%.

CONCLUSION

While imaging-protocol A is accurate if scans at >∼100 h are included, it is time-consuming. In addition to being time-consuming, imaging-protocol B shows high differences associated with organ-count overlay, a lack of accuracy concerning the geometric mean based 2D attenuation correction, and 2D background subtraction due to the inhomogeneous and time-varying background contributions. Our findings indicate that dosimetry based on imaging-protocol C, if appropriately performed, provides similar kidney absorbed doses compared to imaging-protocol A, while only a single scan time-point is necessary.

Results of a prospective randomized trial on long-term effectiveness of protons and carbon ions in prostate cancer: LEM I and α/β = 2 Gy overestimates the RBE

AIM

To analyze the long-term effectiveness of carbon ions relative to protons in the prospective randomized controlled ion prostate irradiation (IPI) trial.

METHODS

Effectiveness via PSA assessment in a randomized study on prostate irradiation with 20x3.3 Gy(RBE) protons versus carbon ions was analyzed in 92 patients. Proton RBE was based on a fixed RBE of 1.1 while the local effect model (LEM) I and an α/β = 2 Gy was used for carbon ions. The dose in the prostate was recalculated based on the delivered treatment plan using LEM I and LEM IV and different α/β values.

RESULTS

Five-year overall and progression free survival was 98% and 85% with protons and 91% and 50% with carbon ions, respectively, with the latter being unexpectedly low compared to Japanese carbon ion data and rather corresponding to a photon dose <72 Gy in 2 Gy fractions. According to LEM I and the applied α/β-value of 2 Gy, the applied carbon ion dose in 2 Gy(RBE) fractions (EQD2) was 87.46 Gy(RBE). Recalculations confirmed a strong dependence of RBE-weighted dose on the α/β ratio as well as on the RBE-model.

CONCLUSION

The data demonstrate a significant lower effectiveness of the calculated RBE-weighted dose in the carbon ion as compared to the proton arm. LEM I and an α/β = 2 Gy overestimates the RBE for carbon ions in prostate cancer treatment. Adjusting the biological dose calculation by using LEM I with α/β = 4 Gy could be a pragmatic way to safely escalate dose in carbon ion radiotherapy for prostate cancer.

Palliative Radiotherapy for Bleeding from Unresectable Gastric Cancer Using Three-Dimensional Conformal Technique

Optimal regimens using recent radiotherapy (RT) equipment for bleeding gastric cancer (GC) have not been fully investigated yet. We retrospectively reviewed the clinical data of 20 patients who received RT for bleeding GC in our institution between 2016 and 2021. Three-dimensional conformal RT was performed. The effectiveness of RT was evaluated by the mean serum hemoglobin (Hb) level and the number of transfused red blood cell (RBC) units 1 month before and after RT. The median first radiation dose was a BED of 39.9 Gy. The treatment success rate was 95% and the rebleeding rate was 10.5%. There was a significant increase in the mean Hb level (8.0 ± 1.1 vs. 9.8 ± 1.3 g/dL, p = 0.01), and a significant decrease in the mean number of transfused RBC units (6.8 ± 3.3 vs. 0.6 ± 1.5 units, p < 0.01). Severe toxicity was observed in two patients (anorexia [n = 1] and gastrointestinal [GI] perforation [n = 1]). Reirradiation was attempted in three patients (for hemostasis [n = 2] and for mass reduction [n = 1]). The retreatment success rate for rebleeding was 100%. GI perforation occurred in two patients who had received hemostatic reirradiation. Palliative RT for bleeding GC using recent technology had excellent efficacy. However, it may be associated with a risk of GI perforation.

Evaluation of the Radiobiological Models predicting the Radiation-Induced Hypothyroidism in the Partially Irradiated Thyroid Gland of Patients with Breast Cancer

Background: Radiation-induced hypothyroidism (RHT) is one of the side effects that might have an impact on the quality of life of patients with breast cancer treated with radiotherapy. Objectives: The aim of the current study was to evaluate the performances of the Lyman-Kutcher-Burman (LKB) and Log-Logistic models in the prediction of hypothyroidism (HT) as well as the estimation of the model parameters for the incidence of RHT among patients with breast cancer. Methods: Fifty-two patients treated with radiation therapy (RT) for breast cancer were prospectively evaluated. Patients' serum samples [tri-iodothyronine, thyroxine, thyroid-stimulating hormone (TSH), free triiodothyronine, and free thyroxine] were measured before RT and also at a regular time interval until 1 year after the completion of RT. For each patient, dose-volume histograms (DVHs) of the thyroid gland were derived from their treatment planning dataset. Patients whose TSH levels were higher than normal with a decrease in FT4 levels were considered as cases with RHT. The LKB and Log-Logistic radiobiological models were evaluated by comparing them with the resultant follow-up data. The parameters for radiobiological models have been deduced by fitting the models to the follow-up data. The models were fitted in a Bayesian setting and compared according to the widely applicable information criterion (WAIC). Results: Twenty-one (40%) patients developed RHT at a follow-up of 1 year after the end of radiation treatment. The fitted values of D50 for the LKB and Log-Logistic models were 37.71 and 25.50 Gy, respectively for the partially irradiated thyroid of patients with breast cancer. The mean time to the incidence of RHT was obtained at 6.7 months in the studied group. Conclusions: A volumetric effect was found for the thyroid gland in the implemented normal tissue complication probability models. Compared to the follow-up data, the Log-Logistic model was ranked as the best model for predicting the rate of RHT in patients with breast cancer.

Local control and radionecrosis of brain metastases from non– small-cell lung cancer treated by hypofractionated stereotactic radiotherapy: Evaluation of predictive factors

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First study on brain metastases 3-fraction SRT from a homogeneous population of NSCLC, according to French MF-SRT recommendations.

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MF-SRT with 3x7.7 Gy on the 70% isodose line and PTV = GTV + 2 mm leads to high local control rates in this population, with acceptable rates of radionecrosis.

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GTV Dmin ≥ 27.4 Gy leads to higher local control.

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Dyslipidemia could be involved in radionecrosis appearance.

Background

The objective of our study was to report predictive factors of local control (LC) and radionecrosis (RN) of brain metastases (BM) of non-small cell lung carcinoma (NSCLC) treated by multifractionated stereotactic radiotherapy (MF-SRT) according to French recommendations.

Method

From 2012 to 2020, 87 patients with 101 BM were retrospectively included. The median age was 63 years (37–85). GTV was defined using contrast-enhanced T1w MRI and was isotropically extended by 2 mm to form PTV. Mean maximum BM diameter was 24.5 mm (10–46). Patients were treated with dynamic arctherapy from May 2012 to February 2016 and then with VMAT. The total prescribed dose was 23.1 Gy prescribed to the encompassing 70% isodose, in 3 fractions.

Results

LC rates at 6 months, 1 year and 2 years was 95.7%, 90.7% and 87.9% respectively. In multivariate analysis, high GTV Dmin (HR = 0.822, p = 0.012) was in favor of better LC whereas a large maximum diameter was predictive of poor LC (HR = 1.124, p = 0.02). GTV Dmin of 27.4 Gy was identified as a discriminant threshold of LC. In case of GTV Dmin ≥ 27.4 Gy, LC at 1 year was 95.3% versus 75.1% with GTV Dmin < 27.4 Gy. Cumulative incidence of RN at 6 months, 1 year and 2 years was 6.3%, 15.4% and 18.1%, respectively. In multivariate analysis, only dyslipidemia was predictive of RN (HR = 2.69, p = 0.03). No dosimetric predictive factor of RN was found in our study.

Conclusion

MF-SRT (3x7.7 Gy on 70% isodose line, with PTV = GTV + 2 mm; according to French recommendations) of BM from NSCLC gives high LC rates with acceptable RN rate. A GTV Dmin of at least 27.4 Gy could be proposed to optimize dosimetric objectives. No dosimetric predictive factors of RN were found in this study. However, dyslipidemia was identified as a potential predictive factor of RN.

Pretherapeutic Comparative Dosimetry of 177Lu-rhPSMA-7.3 and 177Lu-PSMA I&T in Patients with Metastatic Castration-Resistant Prostate Cancer

Radiohybrid prostate-specific membrane antigen (rhPSMA) ligands allow for labeling with 18F and radiometals for endoradiotherapy. rhPSMA-7.3 has been designated as a lead compound with promising preclinical data for 177Lu-rhPSMA-7.3, which has shown higher tumor uptake than 177Lu-PSMA I&T. In this retrospective analysis, we compared pretherapeutic clinical dosimetry data of both PSMA ligands. Methods: Six patients with metastatic castration-resistant prostate cancer underwent both 177Lu-rhPSMA-7.3 and 177Lu-PSMA I&T pretherapeutic dosimetry. Whole-body scintigraphy was performed at 1 h, 4 h, 24 h, 48 h, and 7 d after injection. Regions of interest covering the whole body, organs, bone marrow, and tumor lesions were drawn for each patient. Absorbed doses for individual patients and pretherapeutic applications were calculated using OLINDA/EXM. To facilitate the comparison of both ligands, we introduced the therapeutic index (TI), defined as the ratio of mean pretherapeutic doses to tumor lesions over relevant organs at risk. Results: Mean whole-body pretherapeutic effective doses for 177Lu-rhPSMA-7.3 and 177Lu-PSMA I&T were 0.12 ± 0.07 and 0.05 ± 0.03 Sv/GBq, respectively. Mean absorbed organ doses for 177Lu-rhPSMA-7.3 and 177Lu-PSMA I&T were, for example, 1.65 ± 0.28 and 0.73 ± 0.18 Gy/GBq for the kidneys, 0.19 ± 0.09 and 0.07 ± 0.03 Gy/GBq for the liver, 2.35 ± 0.78 and 0.80 ± 0.41 Gy/GBq for the parotid gland, and 0.67 ± 0.62 and 0.30 ± 0.27 Gy/GBq for the bone marrow, respectively. Tumor lesions received mean absorbed doses of 177Lu-rhPSMA-7.3 and 177Lu-PSMA I&T of 6.44 ± 6.44 and 2.64 ± 2.24 Gy/GBq, respectively. The mean TIs for the kidneys were 3.7 ± 2.2 and 3.6 ± 2.2 for 177Lu-rhPSMA-7.3 and 177Lu-PSMA I&T, respectively, and those for the bone marrow were 15.2 ± 10.2 and 15.1 ± 10.2 for 177Lu-rhPSMA-7.3 and 177Lu-PSMA I&T, respectively. Conclusion: Pretherapeutic clinical dosimetry confirmed preclinical results of mean absorbed doses for tumors that were 2-3 times higher for 177Lu-rhPSMA-7.3 than for 177Lu-PSMA I&T. Absorbed doses to normal organs also tended to be higher for 177Lu-rhPSMA-7.3, resulting overall in similar average TIs for both radiopharmaceuticals with considerable interpatient variability. 177Lu-rhPSMA-7.3 has promise for a therapeutic efficacy similar to that of 177Lu-PSMA I&T at smaller amounts of injected activity, simplifying radiation safety measurements (especially for large patient numbers or dose escalation regimens).

Emerging Role of Carbon Ion Radiotherapy in Reirradiation of Recurrent Head and Neck Cancers: What Have We Achieved So Far?

Administering reirradiation for the treatment of recurrent head and neck cancers is extremely challenging. These tumors are hypoxic and radioresistant and require escalated radiation doses for adequate control. The obstacle to delivering this escalated dose of radiation to the target is its proximity to critical organs at risk (OARs) and possible development of consequent severe late toxicities. With the emergence of highly sophisticated technologies, intensity-modulated radiotherapy (IMRT) and stereotactic body radiotherapy have shown promising outcomes. Proton beam radiotherapy has been used for locally recurrent head and neck cancers because of its excellent physical dose distribution, exploring sharp Bragg peak properties with negligible entrance and exit doses. To further improve these results, carbon ion radiotherapy (CIRT) has been explored in several countries across Europe and Asia because of its favorable physical properties with minimal entrance and exit doses, sharper lateral penumbra, and much higher and variable relative biological efficacy, which cannot be currently achieved with any other form of radiation. Few studies have described the role of CIRT in recurrent head and neck cancers. In this article, we have discussed the different aspects of carbon ions in reirradiation of recurrent head and neck cancers, including European and Asian experiences, different dose schedules, dose constraints of OARs, outcomes, and toxicities, and a brief comparison with proton beam radiotherapy and IMRT.

Three-Dimensional Evaluation of Isodose Radiation Volumes in Cases of Severe Mandibular Osteoradionecrosis for the Prediction of Recurrence after Segmental Resection

Background: Pre-operative margin planning for the segmental resection of affected bone in mandibular osteoradionecrosis (ORN) is difficult. The aim of this study was to identify a possible relation between the received RT dose, exposed bone volume and the progression of ORN after segmental mandibular resection. Method: Patients diagnosed with grade 3-4 ORN for which a segmental resection was performed were included in the study. Three-dimensional reconstructions of RT isodose volumes were fused with postoperative imaging. The primary outcome was the recurrence of ORN after segmental resection. Subsequently, RT exposed mandibular bone volumes were calculated and the location of the bone cuts relative to the isodose volumes were assessed. Results: Five out of thirty-three patients developed recurrent ORN after segmental mandibular resection. All cases with recurrent ORN were resected inside an isodose volume of ≥56 Gy. The absolute mandibular volume radiated with 56 Gy was significantly smaller in the recurrent group (10.9 mL vs. 30.7 mL, p = 0.006), as was the proportion of the mandible radiated with 56 Gy (23% vs. 45%, p = 0.013). Conclusion: The volume of radiated bone was not predictive for risk of progression. The finding that recurrent ORN occurred with bone resection margins within the 56 Gy isodose volume suggests that this could serve as a starting point for the pre-operative planning of reducing the risk of ORN recurrence.

Stereotactic body radiotherapy plus transcatheter arterial chemoembolization for inoperable hepatocellular carcinoma patients with portal vein tumour thrombus: A meta-analysis

Background

The efficacy and safety of stereotactic body radiotherapy (SBRT) plus transcatheter arterial chemoembolization (TACE) versus SBRT or TACE alone(monotherapy) for hepatocellular carcinoma (HCC) patients with portal vein tumour thrombus (PVTT) remains controversial. This meta-analysis was performed to provide more powerful evidence for clinical strategies in inoperable HCC with PVTT.

Methods

We searched the PubMed, EMBASE, Web of Science, Cochrane Library, China Biology Medicine (CBM), China National Knowledge Infrastructure (CNKI), VIP Journal Integration Platform (VIP), and WanFang databases for eligible studies. We pooled the results of 1- and 2-year overall survival rates (OSRs), objective response rates (ORRs), and adverse events (AEs) between the two groups and performed a subgroup meta-analysis for study type, control group, treatment order, and the interval between SBRT and TACE.

Results

Nine studies with 10 cohorts involving 938 patients were included in our meta-analysis. SBRT plus TACE yielded significantly higher 1-year OSR (RR, 1.52[95% CI, 1.33–1.74]), 2-year OSR (RR, 2.00 [95% CI: 1.48–2.70]), ORR (RR = 1.22 [95% CI, 1.08–1.37]), and a lower progression disease (PD) rate (RR = 0.45 [95% CI:0.26–0.79]) than monotherapy. No significant differences were detected in CR, PR, SD, or AEs between the two groups. Subgroup analysis regarding study type, control group, and treatment order indicated that compared with monotherapy, the combination of SBRT with TACE was associated with an increase in 1- and 2-year OSRs but not in ORR. In regard to the interval between SBRT and TACE, subgroup analysis found that the combination therapy for patients with an SBRT-TACE interval <28 days was preferable to monotherapy in the 1- and 2-year OSRs, and ORR. However, for patients with an SBRT-TACE interval ≥28 days, no obvious distinctions were observed in the 1-year OSR, 2-year OSR, or ORR between the two groups.

Conclusion

The combination of SBRT with TACE appears to be better than monotherapy in treating HCC with PVTT and should be recommended for inoperable HCC patients with PVTT.

Radioactive Iodine Treatment for Thyroid Cancer Patients Increases the Risk of Long-Term Gastrointestinal Disorders: A Nationwide Population-Based Cohort Analysis

Simple Summary

The standard treatment for well-differentiated thyroid cancer is thyroidectomy followed by radioactive iodine (RAI) treatment or active surveillance. Despite adequate documentation of acute gastrointestinal adverse effects after RAI treatment, whether the gastrointestinal exposure causes long-term comorbidity or not remained unclear. We conducted a nationwide, population-based retrospective cohort study using the data from the Taiwan National Health Insurance Research Database (NHIRD) to clarify the association between long-term gastrointestinal disorders (including ulcers, atrophic gastritis, and secondary stomach malignancy) and RAI treatment in thyroid cancer patients. We found that patients with RAI treatment were at a significantly higher risk of developing gastric and duodenal ulcers than those without. In addition, a higher cumulative dose is associated with higher risk. Therefore, follow-ups at gastrointestinal clinics might be of great importance for patients presenting with chronic gastrointestinal discomforts, after receiving a single RAI dose of more than 1.11 GBq, and undergoing repeated treatment due to recurrent or residual thyroid cancer.

Abstract

(1) Background: The study aimed to investigate the association between radioactive iodine (RAI) treatment and long-term gastrointestinal disorders including ulcers, atrophic gastritis, and secondary malignant neoplasm of the stomach in patients with thyroid cancer. (2) Methods: The data of the study were extracted from the National Health Insurance Database (NHIRD) of Taiwan between 2000 to 2015. Patients of ages older than 20 with thyroid cancer after thyroidectomy were included and divided into groups with RAI (study cohort) and without RAI (comparison cohort). Multivariate Cox proportional hazards regression analysis and the Kaplan–Meier method were used for statistical analysis. (3) Results: A total of 7250 (with RAI: 5800, without RAI: 1450) patients were included. The Kaplan-Meier analysis revealed a significantly higher cumulative risk for overall gastrointestinal disorders in the group with RAI (log-rank p = 0.034). The risk for gastrointestinal disorders was higher when receiving a cumulative RAI dose higher than 1.11 GBq in the Cox regression analysis. In the subgroup analysis, the risks of gastric and duodenal ulcers are significantly higher in the group with RAI treatment. (4) Conclusions: This study revealed that RAI was associated with an increased risk for long-term gastrointestinal disorders, specifically gastric and duodenal ulcers, in thyroid cancer, especially when the cumulative dose exceeds 1.11 GBq.

Radiation-induced contrast enhancement following proton radiotherapy for low-grade glioma depends on tumor characteristics and is rarer in children than adults

BACKGROUND AND PURPOSE

Proton beam radiotherapy (PRT) is used in the treatment of low-grade glioma (LGG) to mitigate long-term sequelae. Following PRT, increased rates of radiation-induced contrast enhancements (RICE) are suspected but poorly understood.

MATERIALS AND METHODS

We analyzed consecutive 227 patients (42 children and 185 adults) treated with PRT (54Gy RBE) for LGG from 2010 to 2020 and followed with serial clinical exams and magnetic resonance imaging for in median 5.6 years.

RESULTS

Tumors were graded WHO 1 in a minority (n = 22, 12%) of adults, but a majority of children (n = 29, 69%). In contrast, tumors were graded WHO 2 in the majority (n = 160, 87%) of adults and a minority of children (n = 10, 24%). Five-year overall survival following PRT was 81% in adults and 91% in children. The risk of RICE was 5-fold more frequent in adults (25%) versus children (5%) (p = 0.0043). In children and adults, RICE were symptomatic in 50% and 55% (n=1 and 26) of cases with CTCAE grade 0 in 47% (n=23), grade 1 in 25% (n=12), 0% grade 2 (n=0) and 29% grade 3 (n=14), respectively. In adults, RICE risk was associated to WHO grading (8% in WHO grade 1 vs. 24% in WHO grade 2, p = 0.026), independent of age (p=0.44) and irradiation dose (p=0.005), but not independent of IDH mutational status.

CONCLUSIONS

These data demonstrate effectiveness of PRT for LGG in both children and adults. The RICE risk is lower in children which are a main target group for PRT and differs with WHO grading.

Scanning methodology for contact lens-type ocular in vivo dosimeter (CLOD) dosimetry applying a silicone material

PURPOSE

Contact lens-type ocular in vivo dosimeters (CLODs) were recently developed as the first in vivo dosimeter that can be worn directly on the eye to measure the dose delivered to the lens during radiotherapy. However, it has an inherent uncertainty because of its curved shape. Newton's ring effect inevitably occurs because the spacing between the glass window and the active layer is not constant. Furthermore, it involves a large uncertainty because the objective of the CLOD with such morphological characteristics is to measure the dose delivered to an out-of-field lens. In this study, we aimed to investigate the effects of various compensating materials on the sensitivity, accuracy, and uniformity of analysis using a curved CLOD. We developed a new scanning methodology that involves applying a compensating material to reduce the uncertainty caused by the air gap.

METHODS

Four compensating materials-Dragon Skin™ 10 (DS), a transparent silicon material, SORTA-Clear™ 40 (SC), optical grease (OG), and air (no compensating material)-were used in this study. The CLOD was scanned in the reflective mode and transmission mode using each compensating material. We then examined the sensitivity, accuracy, and scan uniformity to evaluate the scanning methodology using compensating materials.

RESULTS

The increase in sensitivity was the highest for OG compared to that for air in the reflective mode. On average, the sensitivity in the reflective mode was higher than that in the transmission mode by a factor of 2.5 for each dose. Among the four compensating materials, OG had the smallest uncertainty. Therefore, the best scan uniformity was achieved when OG was used.

CONCLUSIONS

Scanning methodology was proposed in which a compensating material is applied for a curved lens-type dosimeter. Our results show that OG is the most suitable compensating material to obtain the best accuracy of dose analysis. Following this methodology, the scan uncertainty of curved dosimeters significantly decreased.

Neoplastic nerve lesions

Though metastasis and malignant infiltration of the peripheral nervous system is relatively rare, physicians should have a familiarity with their presentations to allow for prompt diagnosis and initiation of treatment. This article will review the clinical presentations, diagnostic evaluation, and treatment of neoplastic involvement of the cranial nerves, nerve roots, peripheral nerves, and muscle. Due to the proximity of the neural structure traversing the skull base, metastasis to this region results in distinctive syndromes, most often associated with breast, lung, and prostate cancer. Metastatic involvement of the nerve roots is uncommon, apart from leptomeningeal carcinomatosis and bony metastasis with resultant nerve root damage, and is characterized by significant pain, weakness, and numbness of an extremity. Neoplasms may metastasize or infiltrate the brachial and lumbosacral plexuses resulting in progressive and painful sensory and motor deficits. Differentiating neoplastic involvement from radiation-induced injury is of paramount importance as it dictates treatment and prognosis. Neurolymphomatosis, due to malignant lymphocytic infiltration of the cranial nerves, nerve roots, plexuses, and peripheral nerves, deserves special attention given its myriad presentations, often mimicking acquired demyelinating neuropathies.

Effects of Concurrent Exposure to Chronic Restraint-Induced Stress and Total-Body Iron Ion Radiation on Induction of Kidney Injury in Mice

Concurrent exposure to ionizing radiation (IR) and psychological stress (PS) may affect the development of adverse health consequences in scenarios such as space missions, radiotherapy and nuclear accidents. IR can induce DNA damage and cell apoptosis in the kidneys, thus potentially leading to renal fibrosis, which is the ultimate outcome of various chronic progressive nephropathies and the morphological manifestation of a continuous coordinated response after renal injury. However, little is known regarding the effects of concurrent IR exposure and PS on renal damage, particularly renal fibrosis. In this study, using a chronic restraint-induced PS (CRIPS) model, we exposed Trp53-heterozygous mice to total body irradiation with 0.1 or 2 Gy ⁵⁶Fe ions on the eighth day of 28 consecutive days of a restraint regimen. At the end of the restraint period, the kidneys were collected. The histopathological changes and the degree of kidney fibrosis were assessed with H&E and Masson staining, respectively. Fibronectin (FN) and alpha smooth muscle actin (α-SMA), biomarkers of fibrosis, were detected by immunohistochemistry. Analysis of 8-hydroxy-2 deoxyguanosine (8-OHdG), a biomarker of oxidative DNA damage, was performed with immunofluorescence, and terminal deoxynucleotidyl transferase-mediated nick end labeling assays were used to detect apoptotic cells. Histopathological observations did not indicate significant structural damage induced by IR or CRIPS + IR. Western blotting revealed that the expression of α-SMA was much higher in the CRIPS + IR groups than the CRIPS groups. However, no differences in the average optical density per area were observed for FN, α-SMA and 8-OHdG between the IR and CRIPS + IR groups. No difference in the induction of apoptosis was observed between the IR and CRIPS + IR groups. These results suggested that exposure to IR (0.1 and 2 Gy ⁵⁶Fe ions), 28 consecutive days of CRIPS or both did not cause renal fibrosis. Thus, CRIPS did not alter the IR-induced effects on renal damage in Trp53-heterozygous mice in our experimental setup.

Hypofractionated Whole-Breast Irradiation Focus on Coronary Arteries and Cardiac Toxicity-A Narrative Review

Breast cancer is the most common cancer among women worldwide, which is often treated with radiotherapy. Whole breast irradiation (WBI) is one of the most common types of irradiation. Hypo-fractionated WBI (HF-WBI) reduces the treatment time from 5 to 3 weeks. Recent radiobiological and clinical evidence recommended the use of HF-WBI regardless of the age or stage of disease, and it is proven that hypo-fractionation is non-inferior to conventional fractionation regimen irradiation. However, some studies report an increased incidence of heart-related deaths in the case of breast irradiation by hypo-fractionation, especially in patients with pre-existing cardiac risk factors at the time of treatment. Due to the new technical possibilities of radiotherapy techniques, HF-WBI can reduce the risk of cardiac toxicity by controlling the doses received both by the heart and by the anatomical structures of the heart. The radiobiological “double trouble”, in particular “treble trouble”, for hypo-fractionated regimen scan be avoided by improving the methods of heart sparing based on image-guided irradiation (IGRT) and by using respiration control techniques so that late cardiac toxicity is expected to be limited. However, long-term follow-up of patients treated with HF-WBI with modern radiotherapy techniques is necessary considering the progress of systemic therapy, which is associated with long-term survival, and also the cardiac toxicity of new oncological treatments. The still unknown effects of small doses spread in large volumes on lung tissue may increase the risk of second malignancy, but they can also be indirectly involved in the later development of a heart disease. It is also necessary to develop multivariable radiobiological models that include histological, molecular, clinical, and therapeutic parameters to identify risk groups and dosimetric tolerance in order to limit the incidence of late cardiac events. MR-LINAC will be able to offer a new standard for reducing cardiac toxicity in the future, especially in neoadjuvant settings for small tumors.

GOECP/SEOR radiotheraphy guidelines for non-small-cell lung cancer

Non-small cell lung cancer (NSCLC) is a heterogeneous disease accounting for approximately 85% of all lung cancers. Only 17% of patients are diagnosed at an early stage. Treatment is multidisciplinary and radiotherapy plays a key role in all stages of the disease. More than 50% of patients with NSCLC are treated with radiotherapy (curative-intent or palliative). Technological advances-including highly conformal radiotherapy techniques, new immobilization and respiratory control systems, and precision image verification systems-allow clinicians to individualize treatment to maximize tumor control while minimizing treatment-related toxicity. Novel therapeutic regimens such as moderate hypofractionation and advanced techniques such as stereotactic body radiotherapy (SBRT) have reduced the number of radiotherapy sessions. The integration of SBRT into routine clinical practice has radically altered treatment of early-stage disease. SBRT also plays an increasingly important role in oligometastatic disease. The aim of the present guidelines is to review the role of radiotherapy in the treatment of localized, locally-advanced, and metastatic NSCLC. We review the main radiotherapy techniques and clarify the role of radiotherapy in routine clinical practice. These guidelines are based on the best available evidence. The level and grade of evidence supporting each recommendation is provided.

Improving Patients' Life Quality after Radiotherapy Treatment by Predicting Late Toxicities

Personalized treatment and precision medicine have become the new standard of care in oncology and radiotherapy. Because treatment outcomes have considerably improved over the last few years, permanent side-effects are becoming an increasingly significant issue for cancer survivors. Five to ten percent of patients will develop severe late toxicity after radiotherapy. Identifying these patients before treatment start would allow for treatment adaptation to minimize definitive side effects that could impair their long-term quality of life. Over the last decades, several tests and biomarkers have been developed to identify these patients. However, out of these, only the Radiation-Induced Lymphocyte Apoptosis (RILA) assay has been prospectively validated in multi-center cohorts. This test, based on a simple blood draught, has been shown to be correlated with late radiation-induced toxicity in breast, prostate, cervical and head and neck cancer. It could therefore greatly improve decision making in precision radiation oncology. This literature review summarizes the development and bases of this assay, as well as its clinical results and compares its results to the other available assays.

Helical tomotherapy for asymptomatic chemotherapy-refractory or -unfit multiple (3 or more) metastases

Background

Despite chemotherapy innovations, prognosis of patients with chemotherapy-refractory or -unfit multiple metastases (CRMM/CUMM) remains poor. In this prospective study, the efficacy and toxicity of helical tomotherapy for CRMM/CUMM were evaluated.

Materials and methods

Between 2014 and 2020, asymptomatic patients with CRMM/CUMM with ≥ 3 lesions and no prior radiotherapy of the targets were enrolled. Patients who had intolerable toxicities to chemotherapy and those who refused chemotherapy were included in the CRMM and CUMM groups, respectively. Prostate cancer patients and patients with metastases mainly localized in the liver, lung, or brain were excluded. By helical tomotherapy, up to 10 lesions per patient were irradiated in order of volume. The standard dose was 50–60 Gy in 25–30 fractions.

Results

Forty-five patients (median age, 63 years; 35 CRMM/10 CUMM) were enrolled. Primary tumors included lung, gynecological, and gastrointestinal cancers. The most frequently treated targets were lymph node metastases, followed by peritoneal/pleural disseminations and bone tumors. The 1-year survival rate was 51% (median, 12.5 months). In the 35 patients with CRMM, the median survival time was 12.5 months, and the median pre-radiation chemotherapy period was 8.8 months (p > 0.05). The 6-month target control rate was 78%. Acute adverse events (grade ≥ 2) occurred in 33 patients: hematologic toxicities in 23, dermatitis in 6, and others in 8. Late grade ≥ 2 toxicities occurred in 6 patients: pneumonitis in 4 and gastric hemorrhage in 2.

Conclusion

Tomotherapy for CRMM/CUMM resulted in median survival times > 1 year. This treatment should be investigated further in larger prospective studies.

Outcome after Radiotherapy for Vestibular Schwannomas (VS)—Differences in Tumor Control, Symptoms and Quality of Life after Radiotherapy with Photon versus Proton Therapy

Background: To evaluate differences in local tumor control (LC), symptoms and quality of life (QOL) of 261 patients with VS after stereotactic radiosurgery/hypofractionated stereotactic radiotherapy (SRS/HFSRT) vs. fractionated radiotherapy (FRT) vs. fractionated proton therapy (FPT) were studied. Methods: For SRS/HFSRT (n = 149), the median fraction dose applied was 12 Gy. For FRT (n = 87) and FPT (n = 25), the median cumulative doses applied were 57.6 Gy and 54 Gy (RBE), respectively. FRT and FPT used single median doses of 1.8 Gy/Gy (RBE). Median follow-up was 38 months. We investigated dosimetry for organs at risk and analyzed toxicity and QOL by sending out a questionnaire. Results: LC was 99.5% at 12 months after RT with no statistical difference between treatment groups (p = 0.19). LC was significantly lower in NF2 patients (p = 0.004) and in patients with higher tumor extension grade (p = 0.039). The hearing preservation rate was 97% at 12 months after RT with no statistical difference between treatment groups (p = 0.31). Facial and trigeminal nerve affection after RT occurred as mild symptoms with highest toxicity rate in FPT patients. Conclusion: SRS/HFSRT, FRT and FPT for VS show similar overall clinical and functional outcomes. Cranial nerve impairment rates vary, potentially due to selection bias with larger VS in the FRT and FPT group.

New Insights in PRRT: Lessons From 2021

Peptide receptor radionuclide therapy (PRRT) using radiolabeled somatostatin analogs has been used for over two decades for the treatment of well-differentiated neuroendocrine tumors (NETs), and the publication of the NETTER-1 trials has further strengthened its clinical use. However, many aspects of this treatment are still under discussion. The purpose of this review is to collect and discuss the new available evidence, published in 2021, on the use of 177Lu-Oxodotreotide (DOTATATE) or 90Y-Edotreotide (DOTATOC) in adult patients with NETs focusing on the following hot topics: 1) PRRT use in new clinical settings, broaden its indications; 2) the short- and long-term safety; and 3) the identification of prognostic and predictive factors. The review suggests a possible future increase of PRRT applications, using it in other NETs, as a neoadjuvant treatment, or for rechallenge. Regarding safety, available studies, even those with long follow-up, supported the low rates of adverse events, even though 1.8% of treated patients developed a second malignancy. Finally, there is a lack of prognostic and predictive factors for PRRT, with the exception of the crucial role of nuclear imaging for both patient selection and treatment response estimation.

Dosimetry in Lu-177-PSMA-617 prostate-specific membrane antigen targeted radioligand therapy: a systematic review

BACKGROUND

177Lu-prostate-specific membrane antigen (PSMA) gained popularity as a choice of agent in the treatment of patients with advanced prostate cancer or metastatic castration-resistant stage of prostate carcinoma (mCRPC) diseases. However, this treatment may cause fatal effects, probably due to unintended irradiation of normal organs. We performed an extensive systematic review to assess the organs at risk and the absorbed dose received by tumor lesions in 177Lu-PSMA therapy.

DESIGN

In this review, published peer-reviewed articles that cover clinical dosimetry in patients following peptide radionuclide ligand therapy using 177Lu-PSMA have been included. Two senior researchers independently checked the articles for inclusion. A systematic search in the database was made using PubMed, Publons and DOAJ. All selected articles were categorized into three groups: (1) clinical studies with the technical description of dosimetry in 177Lu-PSMA therapy (2) organ dosimetry in 177Lu-PSMA therapy or (3) tumor dosimetry in 177Lu-PSMA therapy.

RESULT

In total, 182 citations were identified on PSMA therapy and 17 original articles on 177Lu-PSMA dosimetry were recognized as eligible for review. The median absorbed dose per unit of administered activity for kidneys, salivary, liver, spleen, lacrimal and bone marrow was 0.55, 0.81, 0.1, 0.1, 2.26 and 0.03 Gy/GBq, respectively. The median absorbed dose per unit of activity for tumor lesions was found in a range of 2.71-10.94 Gy/GBq.

CONCLUSION

177Lu-PSMA systemic radiation therapy (SRT) is a well-tolerated and reliable treatment option against the management of the mCRPC stage of prostate carcinoma. Lacrimal glands and salivary glands are the major critical organs in 177Lu-PSMA SRT. Besides, tumors receive 3-6 times higher absorbed doses compared to organs at risk.

Prediction of chronic kidney disease in abdominal cancers radiation therapy using the functional assays of normal tissue complication probability models

Aim

The purpose of this study is to predict chronic kidney disease (CKD) in the radiotherapy of abdominal cancers by evaluating clinical and functional assays of normal tissue complication probability (NTCP) models.

Materials and Methods

Radiation renal damage was analyzed in 50 patients with abdominal cancers 12 months after radiotherapy through a clinical estimated glomerular filtration rate (eGFR). According to the common terminology criteria for the scoring system of adverse events, Grade 2 CKD (eGFR ≤30-59 ml/min/1.73 m²) was considered as the radiation therapy endpoint. Modeling and parameter estimation of NTCP models were performed for the Lyman-equivalent uniform dose (EUD), the logit-EUD critical volume (CV), the relative seriality, and the mean dose model.

Results

The confidence interval of the fitted parameters was 95%. The parameter value of D₅₀ was obtained 22-38 Gy, and the n and s parameters were equivalent to 0.006 -3 and 1, respectively. According to the Akaike's information criterion, the mean dose model predicts radiation-induced CKD more accurately than the other models.

Conclusion

Although the renal medulla consists of many nephrons arranged in parallel, each nephron has a seriality architecture as renal functional subunits. Therefore, based on this principle and modeling results in this study, the whole kidney organs may have a serial-parallel combination or a secret architecture.

Photodynamic therapy can be safely performed with Talaporfin sodium as a day treatment for central-type early-stage lung cancer

BACKGROUNDS/AIM

Photodynamic therapy (PDT) with Talaporfin sodium (Talaporfin) is an effective and safe treatment for central-type early-stage lung cancer (CELC) that is associated with less skin photosensitivity. However, PDT is mostly performed in hospital for the purpose of light shading management in Japan. It is expected that it will be possible to perform PDT with Talaporfin (Talaporfin-PDT) as a day treatment with ≥14 days of shading management at home. This study aimed to confirm the safety of Talaporfin-PDT as day treatment.

METHODS

We retrospectively investigated the occurrence of adverse events among consecutive patients who received PDT for CELC in a day treatment setting in the Respiratory Endoscopy Division of our institution between January 2010 and February 2020.

RESULTS

A total of 12 patients (16 treatments) received day treatment of Talaporfin-PDT. Among the 12 patients, one patient (one treatment) was followed at another hospital. No severe adverse events after treatment were observed among the remaining 11 patients (15 treatments). Mild photosensitivity on a photosensitivity test was observed in 3 (3 treatments) of the 11 patients (15 treatments) but no major photosensitivity was observed. This photosensitivity was a temporary reaction.

CONCLUSION

Talaporfin-PDT for CELC was safely performed as a day treatment.

A Comparison between Patient- and Physician-Reported Late Radiation Toxicity in Long-Term Prostate Cancer Survivors

Simple Summary

Radiotherapy is widely used as treatment for localized prostate cancer. Due to a high incidence and a good survival after treatment, a large number of prostate cancer survivors are at risk of developing late radiation toxicity. Symptoms may significantly affect quality of life; therefore, the monitoring of toxicities and evaluating their impact are increasingly important matters. Toxicities have always been assessed by physicians, but there is a growing interest in the use of questionnaires to be completed by patients themselves, so-called patient-reported outcome measures. The aim of this study was to compare both outcomes in long-term prostate cancer survivors, and to determine which outcome correlates best with a biological predictor of late radiation toxicity. In symptomatic patients, we found a low agreement; patients assigned greater severity to symptoms than the trial physician assistant did. Neither outcome correlated with the biological predictor. Consideration of both perspectives seems warranted to provide the best care.

Abstract

Patient-reported outcome measures (PROMs) are advocated for the monitoring of toxicity after radiotherapy. However, studies comparing physician- and patient-reported toxicity show low concordance. In this study, we compared physician- and patient-reported toxicity in long-term prostate cancer survivors after radiotherapy, and we determined the correlation with a presumable risk factor for late toxicity: γ-H2AX foci decay ratio (FDR). Patients formerly included in a prospective study were invited to participate in this new study, comprising one questionnaire and one call with a trial physician assistant. Concordance was calculated for seven symptoms. Gamma-H2AX FDRs were determined in ex vivo irradiated lymphocytes in a previous analysis. Associations between FDR and long-term prevalence of toxicity were assessed using univariable logistic regression analyses. The 101 participants had a median follow-up period of 9 years. Outcomes were discordant in 71% of symptomatic patients; in 21%, the physician-assessed toxicity (using CTCAE) was higher, and, in 50%, the patients reported higher toxicity. We did not find a correlation between presence of toxicity at long-term follow-up and FDR. In conclusion, patients assigned greater severity to symptoms than the trial physician assistant did. Consideration of both perspectives may be warranted to provide the best care.

Osteoradionecrosis of the Hip, a Troublesome Complication of Radiation Therapy: Case Series and Systematic Review

Background

Osteoradionecrosis of the hip is a serious complication of radiotherapy that is easily overlooked by physicians and patients in the early stages. There are relatively few reports on this subject, so there is no clear scientific consensus for the pathogenesis, early diagnosis, and clinical treatment of hip osteoradionecrosis. In this paper, we report two cases of hip osteoradionecrosis and systematically review the related literature.

Case Presentation

We report two cases of hip osteoradionecrosis. One patient successfully underwent total hip arthroplasty in our hospital and recovered well postoperatively. Another patient although we offered a variety of surgical options for this patient, the patient was worried that the bone loss would lead to poor prosthesis fixation, resulting in prosthesis loosening and infection, and therefore ultimately refused surgical treatment.

Conclusion

With the development of radiological techniques, the incidence of hip osteoradionecrosis is decreasing year by year, but early diagnosis and rational treatment remain challenging. The effects of non-surgical treatment are limited. Early prevention, early detection, and early intervention are crucial to delay or prevent the emergence of more serious complications.

Doses, fractionations, constraints for stereotactic radiotherapy

This paper describes how to select the most appropriate stereotactic radiotherapy (SRT ) dose and fractionation scheme according to lesion size and site, organs at risk (OARs) proximity and the biological effective dose. In single-dose SRT, 15-34 Gy are generally used while in fractionated SRT 30 and 75 Gy in 2-5 fractions are administered. The ICRU Report No. 91, which is specifically dedicated to SRT treatments, provided indications for dose prescription (with its definition and essential steps), dose delivery and optimal coverage which was defined as the best planning target volume coverage that can be obtained in the irradiated district. Calculation algorithms and OAR s dose constraints are provided as well as treatment planning system characteristics, suggested beam energy and multileaf collimator leaf size. Finally, parameters for irradiation geometry and plan quality are also reported.

Radiation‑induced enterocolitis after combination therapy with palliative radiotherapy and immune checkpoint inhibitors in patients with metastatic lung cancer

The impact of immune checkpoint inhibitors (ICIs) on radiation-induced enterocolitis (RIE) after palliative radiotherapy (PRT) to the bowel has remained to be fully investigated. The aim of the present study was to investigate whether ICIs affect RIE after PRT. For this purpose, 32 lesions (vertebral bone, 13; pelvic bone, 12; adrenal gland, 3; lymph node, 3; liver, 1) in 28 patients with metastatic lung cancer who were treated with both PRT involving the bowel (8-48 Gy; typically 30 Gy in 10 fractions or 20 Gy in 5 fractions) and ICIs between December 2015 and June 2021 were retrospectively reviewed. A total of 12 lesions were treated with ICIs only prior to PRT, 16 received ICIs only after PRT and the remaining 4 received ICIs both prior to and after PRT. The 1-year overall survival rate was 53%. The median PRT dose was 30 Gy (range, 8-48 Gy) in 10 fractions (range, 1-24 fractions). The median interval between PRT and the closest administration of ICIs was 20.5 days (range, 1-212 days). Combination therapy with PRT and ICIs was well tolerated by the majority of patients. However, grade 2 or higher RIE occurred in 6.3% of the patients. In these patients, ICIs were administered within 7 days after completing PRT with 3.6 Gy or a higher-fraction dose (evaluated at the isocenter). There were significant differences in the incidence of RIE between administration of ICIs <7 days after PRT completion and ≥7 days (P=0.05), between <3.6 Gy per fraction and ≥3.6 Gy (P=0.04), and between maximum dose to 2 cc (D2cc) of large bowel <3.3 Gy and D2cc of large bowel ≥3.3 Gy (P=0.02). There was no clear association between the incidence of RIE and any other factors. These results suggest that the administration of ICIs soon after PRT completion and a comparatively high fraction dose may potentially increase the risk of grade 2 or higher RIE.

A Novel Radiotherapeutic Approach to Treat Bulky Metastases Even From Cutaneous Squamous Cell Carcinoma: Its Rationale and a Look at the Reliability of the Linear-Quadratic Model to Explain Its Radiobiological Effects

Introduction

Metastatic cutaneous squamous cell carcinoma (cSCC) is a very rare condition. The lack of definition of an oligometastatic subgroup means that there is no consensus for its treatment, unlike the mucosal head and neck counterpart. Like the latter, the cutaneous form is able to develop bulky tumor masses. When this happens, the classic care approach is just for palliative intent due to a likely unfavorable benefit–risk balance typical of aggressive treatments. Here we proposed a novel radiotherapy (RT) technique to treat bulky metastases from cSCC in the context of an overall limited tumor burden and tried to explain its clinical outcome by the currently available mathematical radiobiological and ad hoc developed models.

Methods

We treated a case of facial cSCC with three metastases: two of them by classic stereotactic RT and the other by lattice RT supported by metabolic imaging (¹⁸F-FDG PET) due to its excessively large dimensions. For the latter lesion, we compared four treatment plans with different RT techniques in order to define the best approach in terms of normal tissue complication probability (NTCP) and tumor control probability (TCP). Moreover, we developed an ad hoc mathematical radiobiological model that could fit better with the characteristics of heterogeneity of this bulky metastasis for which, indeed, a segmentation of normoxic, hypoxic, and necrotic subvolumes might have been assumed.

Results

We observed a clinical complete response in all three disease sites; the bulky metastasis actually regressed more rapidly than the other two treated by stereotactic RT. For the large lesion, NTCP predictions were good for all four different plans but even significantly better for the lattice RT plan. Neither the classic TCP nor the ad hoc developed radiobiological models could be totally adequate to explain the reported outcome. This finding might support a key role of the host immune system.

Conclusions

PET-guided lattice RT might be safe and effective for the treatment of bulky lesions from cSCC. There might be some need for complex mathematical radiobiological models that are able to take into account any immune system’s role in order to explain the possible mechanisms of the tumor response to radiation and the relevant key points to enhance it.

EANM dosimetry committee recommendations for dosimetry of 177Lu-labelled somatostatin-receptor- and PSMA-targeting ligands

The purpose of the EANM Dosimetry Committee is to provide recommendations and guidance to scientists and clinicians on patient-specific dosimetry. Radiopharmaceuticals labelled with lutetium-177 (177Lu) are increasingly used for therapeutic applications, in particular for the treatment of metastatic neuroendocrine tumours using ligands for somatostatin receptors and prostate adenocarcinoma with small-molecule PSMA-targeting ligands. This paper provides an overview of reported dosimetry data for these therapies and summarises current knowledge about radiation-induced side effects on normal tissues and dose-effect relationships for tumours. Dosimetry methods and data are summarised for kidneys, bone marrow, salivary glands, lacrimal glands, pituitary glands, tumours, and the skin in case of radiopharmaceutical extravasation. Where applicable, taking into account the present status of the field and recent evidence in the literature, guidance is provided. The purpose of these recommendations is to encourage the practice of patient-specific dosimetry in therapy with 177Lu-labelled compounds. The proposed methods should be within the scope of centres offering therapy with 177Lu-labelled ligands for somatostatin receptors or small-molecule PSMA.

Comparison of External Beam Radiation Therapy Modalities for Hepatocellular Carcinoma With Macrovascular Invasion: A Meta-Analysis and Systematic Review

Purpose

We performed a systematic review and meta-analysis to compare external beam radiation therapy modalities for hepatocellular carcinoma (HCC) with macrovascular invasion (MVI).

Methods

Studies were selected from online databases from the date of inception to November 2021. The outcomes of interest were overall survival (OS), objective response rate (ORR), and local control rate (LCR).

Results

Forty-four studies (n = 3730) were selected from 1050 articles. The pooled 1-year OS were 60.9%, 45.3%, and 44.9 for particle radiotherapy (PRT) group, conventional radiotherapy (CRT), and stereotactic body radiotherapy (SBRT) group, respectively; p = 0.005 and 0.002 for PRT vs. CRT and SBRT, respectively. Both the PRT group and the SBRT group have the advantage over the CRT group in the pooled ORR. The PRT group showed significantly higher than the CRT group (p = 0.007) in LCR. For combination therapy, CRT plus transarterial chemoembolization can prolong survival than CRT alone (p = 0.006 for 1-year OS; p = 0.014 for 2-year OS). Among grade ≥ 3 complications, the most frequent type of toxicity in CRT, SBRT, PRT group was hematological toxicity, hepatotoxicity, dermatological toxicity, respectively.

Conclusions

Among patients with HCC with MVI, the 1-year OS and the 2-year OS were both higher in the PRT group than in the CRT, SBRT groups. The ORR was similar between the PRT and SBRT groups. The combination therapy based on radiotherapy is expectable. PRT is associated with less complications than photon radiotherapy.

Ocular, Orbital, and Adnexal Toxicity With High-dose Volumetric Modulated Arc Radiation Therapy for Orbital Malignancies

PURPOSE

Conventional modalities of external-beam radiation therapy (EBRT) are associated with high incidences of severe vision-threatening ocular and orbital toxicities when used to treat orbital malignancies. We investigate toxicities associated with high-dose volumetric modulated arc therapy (VMAT), a commonly used contemporary treatment modality for these tumors.

METHODS

Retrospective analysis of malignant orbital tumors managed with adjuvant high-dose VMAT preceded by globe-salvaging surgical therapy (GST) or exenteration. Dosimetric quantitation of target volumes and critical structures was performed. Incidence and severity of ocular, orbital, and adnexal toxicities were evaluated and assessed with regard to conventional EBRT toxicities for orbital malignancies described in the literature.

RESULTS

Eighty-four subjects (mean age = 65.9 ± 9.7 years) were included (N = 48 and N = 36 in GST and exenteration subgroups, respectively). Mean dose was 64.8 ± 2.1 Gy to the planning target volume. Dosing to critical structures typically did not surpass known tissue tolerance limits. Median follow up was 18.3 months. Visual acuity in the GST subgroup was not significantly different after VMAT (0.25 ± 0.06) compared with baseline (0.23 ± 0.02; P = 0.302). Whereas severe toxicities reported by major systematic analyses in the literature with older EBRT modalities were relatively common-for example, retinopathy (16-40%), optic neuropathy (16%), and corneal perforation (13%)-toxicities with VMAT were typically mild and less common. The most common toxicities with VMAT were mild dry eye (81.3%; 39/48), cataract (21.1%; 8/38 phakic eyes), and periocular dermatitis (15.5%; 13/84). Vision-threatening toxicities, including severe corneal pathologies, retinopathy, or optic neuropathy, were rare. There were no contralateral ocular or adnexal toxicities.

CONCLUSIONS

High-dose VMAT for orbital malignancies demonstrated low incidence and severity of eye-related toxicity, in contradistinction to adverse events reported from conventional forms of radiotherapy.

Radiolabeled Somatostatin Analogues for Diagnosis and Treatment of Neuroendocrine Tumors

Neuroendocrine neoplasms (NENs) are rare and heterogeneous tumors that require multidisciplinary discussion for optimal care. The theranostic approach (DOTA peptides labelled with 68Ga for diagnosis and with 90Y or 177Lu for therapy) plays a crucial role in the management of NENs to assess disease extension and as a criteria for peptide receptor radionuclide therapy (PRRT) eligibility based on somatostatin receptor (SSTR) expression. On the diagnostic side, [68Ga]Ga-DOTA peptides PET/CT (SSTR PET/CT) is the gold standard for imaging well-differentiated SSTR-expressing neuroendocrine tumors (NETs). [18F]FDG PET/CT is useful in higher grade NENs (NET G2 with Ki-67 > 10% and NET G3; NEC) for more accurate disease characterization and prognostication. Promising emerging radiopharmaceuticals include somatostatin analogues labelled with 18F (to overcome the limits imposed by 68Ga), and SSTR antagonists (for both diagnosis and therapy). On the therapeutic side, the evidence gathered over the past two decades indicates that PRRT is to be considered as an effective and safe treatment option for SSTR-expressing NETs, and is currently included in the therapeutic algorithms of the main scientific societies. The positioning of PRRT in the treatment sequence, as well as treatment personalization (e.g., tailored dosimetry, re-treatment, selection criteria, and combination with other alternative treatment options), is warranted in order to improve its efficacy while reducing toxicity. Although very preliminary (being mostly hampered by lack of methodological standardization, especially regarding feature selection/extraction) and often including small patient cohorts, radiomic studies in NETs are also presented. To date, the implementation of radiomics in clinical practice is still unclear. The purpose of this review is to offer an overview of radiolabeled SSTR analogues for theranostic use in NENs.