Impact of hydrogel spacer injections on interfraction prostate motion during prostate cancer radiotherapy.

Background The dosimetric advantage of prostate-rectum spacers to displace the anterior rectal wall outside of the high-dose radiation regions has been clearly established in prostate cancer radiotherapy (RT). The aim of this study was to assess the impact of hydrogel spacer (HS) in the interfraction prostate motion in patients undergoing RT for prostate cancer. Material and methods Twenty prostate cancer patients implanted with three fiducial markers (FM) with (n = 10) or without (n = 10) HS were analyzed. Displacements between the prostate isocenter based on the FM's position and the bony anatomy were quantified in the left-right (LR), anterior-posterior (AP), superior-inferior (SI) axes by offline analyses of 122 cone beam computed tomography scans. Group systematic (M), systematic (Σ) and random (σ) setup errors were determined. Results In patients with or without HS, the overall mean interfraction prostate displacements were 0.4 versus -0.4 mm (p = 0.0001), 0.6 versus 0.6 mm (p = 0.85), and -0.6 mm versus -0.3 mm (p = 0.48) for the LR, AP, and SI axes, respectively. Prostate displacements >5 mm in the AP and SI directions were similar for both groups. No differences in M, Σ and σ setup errors were observed in the three axes between HS + or HS- patients. Conclusions HS implantation does not significantly influence the interfraction prostate motion in patients treated with RT for prostate cancer. The major expected benefit of HS is a reduction of the high-dose levels to the rectal wall without influence in prostate immobilization.

Sexual organ-sparing with hydrogel spacer injections for rectal cancer radiotherapy: a feasibility pilot study.

OBJECTIVES: The aim of this pilot study was to investigate in two rectal cancer patients undergoing neoadjuvant chemo-radiotherapy (nCRT) the implant feasibility and dosimetric benefit in sexual organ-sparing of an injectable, absorbable, radiopaque hydrogel spacer. METHODS: Two rectal cancer patients (one male and one female) underwent hydrogel implant between rectum and vagina/prostate before nCRT and curative surgery. A CT scan was performed before and after injection and a comparative dosimetric study was performed testing a standard (45/50 Gy) and a dose escalated (46/55.2 Gy) schedule. RESULTS: In both patients, the spacer implant in the recto-prostatic or recto-vaginal space was feasible and well tolerated. For the male, the dosimetric benefit with spacer was minimal for sexual organs. For the female however, doses delivered to the vagina were significantly reduced with spacer with a mean reduction of more than 5 Gy for both regimens. CONCLUSIONS: For organ preservation protocols and selected sexually active female patients, use of hydrogel spacers can be considered to spare sexual organs from the high radiotherapy dose levels. ADVANCES IN KNOWLEDGE: For females with advanced rectal tumor, a spacer implant between the rectum and the vagina before nCRT is feasible and reduces doses delivered to the vagina.

Postmastectomy radiotherapy in T1-2 patients with one to three positive lymph nodes - Past, present and future.

PAST: The role of post-mastectomy radiotherapy (PMRT) in patients with tumor <5 cm and one to three positive lymph nodes after axillary dissection (ALND) is vigorously debated. Initial doubts over the efficacy and safety of PMRT in these patients were partially overcome by improvement in technology and systemic treatments. Several randomized controlled clinical trials confirmed benefit of PMRT in N1 patients, which were meta-analyzed by the Early Breast Cancer Trialists' Collaborative Group (EBCTCG). This meta-analysis provides the sole high-level evidence to guide clinical decision-making. PRESENT: Nevertheless, concerns have been evoked around these results, most notably concerning the patient selection bias and the era in which the patients were treated. More recent studies, albeit retrospective, are in contrast with this level I evidence, unequivocally reporting inferior recurrence rates in control arms than those of the EBCTCG meta-analysis. Taken together, these results suggest that one solution would not fit all N1 patients and that patient selection for PMRT shall be stratified upon risks factors. Most prominent of such factors identified are: patient age; number and ratio of positive lymph nodes; histological features such as lymphovascular invasion; and hormone receptor expression. FUTURE: A prospective randomized controlled trial SUPREMO will release its final results in 2023 and shed light onto the subject. Genomic tumor cell profiling will likely provide further guidelines in terms of risk stratification. SUPREMO translational sub-study will also offer material for genomic analyses. A cross-field tendency to forgo nodal dissection in favor of sentinel lymph node biopsy followed by nodal irradiation might eventually render the question of PMRT indication after ALND irrelevant.

Prophylactic cranial irradiation in extensive disease small cell lung cancer: An endless debate.

Extensive disease Small cell lung cancer (ED-SCLC) represents a very aggressive malignancy in which brain metastases (BM) are quite common. Clinical trials on prophylactic cranial irradiation (PCI) have showed a clear decrease in the risk of developing BM but conflicting results concerning a possible survival advantage. A landmark European Organisation for Research and Treatment of Cancer (EORTC) prospective trial, as well as multitude of retrospective series confirm survival benefit after PCI. Recently, a Japan Clinical Oncology Group (JCOG) study did not find such survival benefit, provided that non-irradiated patients are closely followed by MRI. Henceforth, the role of PCI in this population has been questioned, on the ground of the possible absence of survival benefit, leading to a gradual shift in oncology practice. We performed a review of the literature on the subject of PCI in ED-SCLC patients. We conclude that PCI could still play a crucial role in these patients, considering not only a possible survival benefit, but also alternative endpoints, such as improved local control, delay in the onset of symptomatic BM and lower toxicity of a prophylactic- rather than an eventual active-intent treatment. Individualized attitude should be discussed with patients, while addressing all arguments in favour and against PCI.

Clinical experience with lung-specific electromagnetic transponders for real-time tumor tracking in lung stereotactic body radiotherapy.

BACKGROUND AND PURPOSES: Motion management is crucial for optimal stereotactic body radiotherapy (SBRT) of moving targets. We aimed to describe our clinical experience with real-time tracking of lung-specific electromagnetic transponders (EMTs) for SBRT of early stage non-small cell lung cancer in free-breathing (FB) or deep inspiration breath-hold (DIBH). MATERIAL AND METHODS: Seven patients were implanted with EMTs. Simulation for SBRT was performed in FB and in DIBH. We prescribed 60 Gy in 3, 5 or 8 fractions to the tumor and delivered SBRT with volumetric modulated arcs and a 6 MV flattening filter free photon beam. Patients' setup at the linac was performed using EMT positions and cone-beam CT (CBCT) verification. Four patients were treated in DIBH because of a dosimetric benefit. We analysed patient alignment and treatment delivery parameters using DIBH or FB and EMT real-time tracking. RESULTS: There were no complications from the EMT implantation. Visual inspection of CBCT before and/or after SBRT revealed good alignment of structures and EMTs. The median setup time was 9.8 min (range: 4.6-34.1 min) and the median session time was 14.7 min (range: 7.3-36.5 min). EMT positions in lungs remained stable during overall treatment and allowed real-time tracking both in FB and in DIBH SBRT. The treatment beam was gated when EMT centroid position exceeded tolerance thresholds ensuring correct delivery of radiation to the tumor. CONCLUSION: Using EMTs for real-time tracking of tumor motion during lung SBRT proved to be safe, accurate and easy to integrate clinically for treatments in FB or DIBH.

Hypofractionated radiotherapy for prostate cancer in the postoperative setting: What is the evidence so far?

Postoperative external beam radiation therapy (EBRT) is a validated treatment option in the adjuvant setting for prostate cancer patients with aggressive pathological features following radical prostatectomy (RP) or as salvage modality in patients with biochemical recurrence after RP. Contemporary randomized phase III trials have provided evidence for using hypofractionation in the definitive treatment setting as an alternative to standard fractionated regimens. Biomathematical modeling for prostate cancer fractionated EBRT associated with widely available refined treatment delivery techniques such as volumetric modulated-arc therapy with image-guided RT may improve the therapeutic ratio. Nevertheless, the role of hypofractionation in the postoperative setting still remains investigational. In this systematic review of the literature we reviewed the role of hypofractionation for postoperative EBRT in the adjuvant or salvage setting in prostate cancer patients previously treated by RP. A favorable acute toxicity profile with, at least, as good biochemical control rates with hypofractionation has been suggested. And yet conflicting results have been reported concerning long-term genitourinary late toxicity. Prospective studies are eagerly awaited to assess the role of hypofractionation in the postoperative setting.

Comparison of the incidence of osteoradionecrosis with conventional radiotherapy and intensity-modulated radiotherapy.

BACKGROUND: Modern techniques of radiotherapy are supposed to decrease the incidence of osteoradionecrosis of the mandible (ORNM). The purpose of this study was to compare the incidence of ORNM after intensity-modulated radiotherapy (IMRT) in comparison to conventional 3D conformal radiotherapy techniques (conventional RT). METHODS: We conducted a retrospective study of consecutive unselected patients treated in a single institution between 2002 and 2012. To minimize confounding effects, only patients with oropharyngeal carcinoma without surgery of the primary site were included. RESULTS: The cohorts included 145 patients in the conventional RT group and 89 patients in the IMRT group. Total incidence rate of ORNM was similar for both groups with rates of 11% versus 10% (n = 16 for conventional RT and n = 9 for IMRT; p = 1.0). Subanalysis revealed more ORNM in T4 classified lesions with IMRT (p = .007). Analysis of different risk factors showed no statistically significant difference between ORNM and no-ORNM patients. CONCLUSION: We found no reduction in ORNM with IMRT. © 2016 Wiley Periodicals, Inc. Head Neck 38: 1708-1716, 2016.