Whole brain radiotherapy plus simultaneous in-field boost with image guided intensity-modulated radiotherapy for brain metastases of non-small cell lung cancer

Adding simultaneous integrated boost to whole brain radiation therapy improved intracranial tumour control and minimize radiation-induced brain injury risk for the treatment of brain metastases

BACKGROUND

Brain metastases (BMs) are the most frequent intracranial tumours associated with poor clinical outcomes. Radiotherapy is essential in the treatment of these tumours, although the optimal radiation strategy remains controversial. The present study aimed to assess whether whole brain radiation therapy with a simultaneous integrated boost (WBRT + SIB) provides any therapeutic benefit over WBRT alone.

METHODS

We included and retrospectively analysed 82 patients who received WBRT + SIB and 83 who received WBRT alone between January 2012 and June 2021. Intracranial progression-free survival (PFS), local tumour control (LTC), overall survival (OS), and toxicity were compared between the groups.

RESULTS

Compared to WBRT alone, WBRT + SIB improved intracranial LTC and PFS, especially in the lung cancer subgroup. Patients with high graded prognostic assessment score or well-controlled extracranial disease receiving WBRT + SIB had improved intracranial PFS and LTC. Moreover, WBRT + SIB also improved the long-term intracranial tumour control of small cell lung cancer patients. When evaluating toxicity, we found that WBRT + SIB might slightly increase the risk of radiation-induced brain injury, and that the risk increased with increasing dosage. However, low-dose WBRT + SIB had a tolerable radiation-induced brain injury risk, which was lower than that in the high-dose group, while it was comparable to that in the WBRT group.

CONCLUSIONS

WBRT + SIB can be an efficient therapeutic option for patients with BMs, and is associated with improved intracranial LTC and PFS. Furthermore, low-dose WBRT + SIB (biologically effective dose [BED] ≤ 56 Gy) was recommended, based on the acceptable risk of radiation-induced brain injury and satisfactory tumour control.

TRIAL REGISTRATION

Retrospectively registered.

Application of piecewise VMAT technique to whole-brain radiotherapy with simultaneous integrated boost for multiple metastases

PURPOSE

This study implemented a piecewise volumetric modulated arc therapy (P-VMAT) for realizing whole-brain radiation therapy (WBRT) with simultaneous integrated boost (SIB) for multiple brain metastases (> 40 metastases) with a conventional C-arm linear accelerator.

MATERIALS AND METHODS

This study retrospectively analyzed 10 patients with multiple brain metastases (40-120 metastases, median 76), who underwent WBRT and SIB using helical tomotherapy (HT). The prescribed doses were 40 Gy/20 f and 60 Gy/20 f for WBRT and SIB, respectively. Corresponding new HT plans were designed with P-VMAT using 7 arcs. For each arc, the collimator was rotated to 45°, and the field width was limited to 2.5 cm with 0.5 cm overlap with adjacent arcs. Thus, each arc covered only one section of the brain target volume. A conventional dual arc VMAT (DA-VMAT) plan was also designed. HT, P-VMAT, and DA-VMAT plans were compared using dose distribution reviews and dosimetric parameters. ArcCHECK phantom measurements were performed for verification of P-VMAT plans.

RESULTS

No significant differences in the mean coverage of the whole-brain target and metastases were observed between HT and P-VMAT (p > 0.05). The conformity index for the whole-brain target improved with P-VMAT compared with HT (p < 0.05). Furthermore, the volume of 44 Gy V₄₄ (110% of prescribed dose for WBRT) received for whole-brain significantly reduced with P-VMAT from 38.2 ± 12.9% to 23.3 ± 9.4% (p < 0.05), and the maximum dose for organs at risks such as the hippocampus, optical nerve, optical chiasm, and spinal cord declined with P-VMAT (p < 0.05). Unlike HT and P-VMAT, DA-VMAT was clinically unacceptable because V₄₄ in the whole-brain was too high (54.7 ± 8.2%). The mean absolute dose gamma passing rate for P-VMAT plans was 97.6 ± 1.1% (3%/3 mm criterion, 10%).

CONCLUSIONS

P-VMAT is favorable for WBRT and SIB for multiple brain metastases. It provides comparable coverage of whole-brain target and SIB, with better conformity, lower V_44, and better dose sparing of organs at risk compared with HT. Furthermore, results show that DA-VMAT fails clinical practice even for a relatively large number of brain metastases with a high degree of plan complexity. The patient specific verification demonstrates the feasibility of P-VMAT for clinical application.

Modern Radiation Therapy for the Management of Brain Metastases From Non-Small Cell Lung Cancer: Current Approaches and Future Directions

Brain metastases (BMs) represent the most frequent event during the course of Non-Small Cell Lung Cancer (NSCLC) disease. Recent advancements in the diagnostic and therapeutic procedures result in increased incidence and earlier diagnosis of BMs, with an emerging need to optimize the prognosis of these patients through the adoption of tailored treatment solutions. Nowadays a personalized and multidisciplinary approach should rely on several clinical and molecular factors like patient’s performance status, extent and location of brain involvement, extracranial disease control and the presence of any “druggable” molecular target. Radiation therapy (RT), in all its focal (radiosurgery and fractionated stereotactic radiotherapy) or extended (whole brain radiotherapy) declinations, is a cornerstone of BMs management, either alone or combined with surgery and systemic therapies. Our review aims to provide an overview of the many modern RT solutions available for the treatment of BMs from NSCLC in the different clinical scenarios (single lesion, oligo and poly-metastasis, leptomeningeal carcinomatosis). This includes a detailed review of the current standard of care in each setting, with a presentation of the literature data and of the possible technical solutions to offer a “state-of-art” treatment to these patients. In addition to the validated treatment options, we will also discuss the future perspectives on emerging RT technical strategies (e.g., hippocampal avoidance whole brain RT, simultaneous integrated boost, radiosurgery for multiple lesions), and present the innovative and promising findings regarding the combination of novel targeted agents such as tyrosine kinase inhibitors and immune checkpoint inhibitors with brain irradiation.

Whole-Brain Radiation Therapy With Simultaneous Integrated Boost Versus Whole-Brain Radiation Therapy Plus Stereotactic Radiosurgery for the Treatment of Brain Metastasis From Lung Cancer

Radiotherapy is one of the most important treatments for brain metastasis (BM). This study aimed to assess whether whole-brain radiation therapy (WBRT) with simultaneous integrated boost (SIB) provided any therapeutic benefit compared to WBRT followed by stereotactic radiosurgery (SRS). Seventy-two consecutive cases of lung cancer with BM treated from January 2014 to June 2020 were analyzed retrospectively. Thirty-seven patients were treated with WBRT (30 Gy in 10 fractions) and SIB (45 Gy in 10 fractions), and 35 patients were treated with WBRT (30 Gy in ten fractions) followed by SRS (16–24 Gy according to the maximum tumor diameter). The primary endpoint was intracranial progression-free survival (PFS). The secondary endpoints were intracranial objective response (partial and complete responses), pattern of intracranial progression, overall survival (OS), and toxicity. The WBRT + SIB group had a significantly longer median intracranial PFS (9.1 vs. 5.9 months, P = 0.001) than the WBRT + SRS group. The intracranial objective response rate was 67.6% and 62.9% in the WBRT + SIB and in WBRT + SRS groups, respectively (P = 0.675). The incidence of progression outside the P-GTV in the WBRT + SIB group was significantly lower than that in the WBRT + SRS group (39.4% vs. 75.0%, P = 0.004). The median OS was 24.3 and 20.3 months in the WBRT + SIB and WBRT + SRS groups, respectively (P = 0.205). There was no significant difference in the incidence of grade 3 or worse adverse reactions between the two groups. Compared to treatment with WBRT + SRS, that with WBRT + SIB for BM appeared to contribute to local control.

Concurrent Apatinib and Brain Radiotherapy in Patients With Brain Metastases From Driver Mutation-negative Non-small-cell Lung Cancer: Study Protocol for an Open-label Randomized Controlled Trial

Brain radiotherapy (BR) is a well-recognized approach for multiple brain metastases (BMs) from non-small-cell lung cancer (NSCLC). However, the prognosis for these patients remains poor. Apatinib, an antiangiogenic agent targeting vascular endothelial growth factor receptor-2, has shown excellent efficacy in multiple solid tumors. This phase II (WWW. ClinicalTrials.gov Identifier: VEGFR-2 NCT03801200) randomized trial aims to evaluate the efficacy and safety of this combined modality paradigm in patients with BMs from driver mutation-negative NSCLC. This is a multicenter, open-label, randomized controlled clinical trial. A total of 90 eligible patients will be allocated in a 1:1 ratio, to either the experimental group (concurrent apatinib and BR) or the control group (BR alone). The primary endpoint is intracranial progression-free survival. The secondary endpoints include intracranial objective response rate, intracranial disease control rate, intracranial time to progression, overall survival, and occurrence of peritumoral brain edema using standardized measurement. Quality of life and adverse events will also be evaluated. Assessments will be carried out before enrollment (baseline) along with 4 and 12 weeks after radiotherapy, followed by every 12 weeks thereafter and up to 24 months. In summary, the aim of this trial is to demonstrate the clinical efficacy and safety of concurrent BR and apatinib in patients with driver mutation-negative NSCLC with multiple BMs, in efforts to expand management options for this population with poor prognosis.

Congress of Neurological Surgeons Systematic Review and Evidence-Based Guidelines on Treatment Options for Adults With Multiple Metastatic Brain Tumors

TARGET POPULATION

These recommendations apply to adult patients newly diagnosed with multiple (more than 1) brain metastases.

QUESTION 1

In what circumstances should whole brain radiation therapy be recommended to improve tumor control and survival in patients with multiple brain metastases?

RECOMMENDATION

Level 2: It is recommended that whole brain radiation therapy can be added to stereotactic radiosurgery to improve local and distant control keeping in mind the potential for worsened neurocognitive outcomes and that there is unlikely to be a significant impact on overall survival.

QUESTION 2

In what circumstances should stereotactic radiosurgery be recommended to improve tumor control and survival in patients with multiple brain metastases?

RECOMMENDATIONS

Level 1: In patients with 2 to 3 brain metastases not amenable to surgery, the addition of stereotactic radiosurgery to whole brain radiation therapy is not recommended to improve survival beyond that obtained with whole brain radiation therapy alone. Level 3: The use of stereotactic radiosurgery alone is recommended to improve median overall survival for patients with more than 4 metastases having a cumulative volume < 7 cc.

QUESTION 3

In what circumstances should surgery be recommended to improve tumor control and survival in patients with multiple brain metastases?

RECOMMENDATION

Level 3: In patients with multiple brain metastases, tumor resection is recommended in patients with lesions inducing symptoms from mass effect that can be reached without inducing new neurological deficit and who have control of their cancer outside the nervous system.The full guideline can be found at https://www.cns.org/guidelines/guidelines-treatment-adults-metastatic-brain-tumors/chapter_6.

Relationship between WBRT total dose, intracranial tumor control, and overall survival in NSCLC patients with brain metastases - a single-center retrospective analysis

Background

The relationship between whole brain radiotherapy (WBRT) dose with intracranial tumor control and overall survival (OS) in patients with non-small cell lung cancer (NSCLC) brain metastases (BM) is largely unknown.

Methods

We retrospectively analyzed 595 NSCLC BM patients treated consecutively at the Fourth Hospital of Hebei Medical University between 2013 to 2015. We assigned the patients into 4 dose groups of WBRT: none, < 30, 30–39, and ≥ 40 Gy and assessed their relationship with OS and intracranial progression-free survival (iPFS). Cox models were utilized. Covariates included sex, age, KPS, BM lesions, extracranial metastasis, BM and lung tumor resection, chemotherapy, targeted therapy, and focal radiotherapy modalities.

Results

Patients had a mean age of 59 years and were 44% female. Their median survival time (MST) of OS and iPFS were 9.3 and 8.9 months. Patients receiving none (344/58%), < 30 (30/5%), 30–39 (93/16%), and ≥ 40 (128/22%) Gy of WBRT had MST of OS (iPFS) of 7.3 (6.8), 6.0 (5.4), 10.3 (11.9) and 11.9 (11.9) months, respectively. Compared to none, other WBRT groups had adjusted HRs for OS - 1.23 (p > 0.20), 0.72 (0.08), 0.61 (< 0.00) and iPFS - 1.63 (0.03), 0.71 (0.06), 0.67 (< 0.01). Compared to 30–39 Gy, WBRT dose ≥40 Gy was not associated with improved OS and iPFS (all p > 0.40). Stratified analyses by 1–3 and ≥ 4 BM lesions and adjustment analyses by each prognostic index of RPA class, Lung-GPA and Lung-molGPA supported these relationships as well.

Conclusions

Compared to none, WBRT doses ≥30 Gy are invariably associated with improved intracranial tumor control and survival in NSCLC BM patients.

Survival and intracranial control outcomes of whole-brain radiotherapy (WBRT) alone versus WBRT plus a radiotherapy boost in non-small-cell lung cancer with brain metastases: a single-institution retrospective analysis

Purpose: To compare the differences in survival and intracranial local control between patients treated with whole-brain radiotherapy (WBRT) and WBRT plus a radiotherapy boost (RTB) in non-small-cell lung cancer (NSCLC) patients with brain metastases (BMs).

Patients and methods: Between May 2010 and October 2017, 206 NSCLC patients with BMs were treated with brain radiotherapy; among these patients, 140 patients underwent WBRT alone (group A) and 66 patients underwent WBRT plus RTB (group B). The endpoints included intracranial local progression-free survival and regional progression-free survival time (iLPFS and iRPFS, respectively) and overall survival (OS).

Results: Between the two groups, not all baseline clinical factors were well-balanced. The median iLPFS was 17.9 months in group A and 22.3 months in group B. The 2-year iLPFS rates were significantly lower in group A than in group B (34.5% vs 49.3%, P=0.041); however, no significant differences were observed in OS or iRPFS. Multivariate analyses revealed that epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) therapy was significantly associated with good OS, iLPFS, and iRPFS. Among the patients treated with TKIs (n=62), there were no differences in OS (P=0.190), iLPFS (P=0.334), or iRPFS (P=0.338) between groups A and B. In the patients without TKI treatment (n=102), the median iLPFS was significantly longer in group B than in group A (16.7 vs 12.0 months, P=0.032), but no significant differences were found in OS (p=0.182) or iRPFS (P=0.837) between the two groups.

Conclusion: WBRT plus RTB significantly improved iLPFS compared with WBRT alone, especially in patients without EGFR-TKI treatment. However,there were no significant differences in iRPFS or OS between the two groups. Patients treated with EGFR-TKIs may not benefit from WBRT plus RTB.

Dosimetric evaluation of four whole brain radiation therapy approaches with hippocampus and inner ear avoidance and simultaneous integrated boost for limited brain metastases

AIMS

To perform a dosimetric evaluation of four different simultaneous integrated boost whole brain radiotherapy modalities with hippocampus and inner ear avoidance in the treatment of limited brain metastases.

METHODS

Computed tomography/magnetic resonance imaging data of 10 patients with limited (1-5) brain metastases were used to replan step-and-shoot intensity-modulated radiotherapy (sIMRT), dynamic intensity-modulated radiation therapy (dIMRT), volumetric-modulated arc therapy (VMAT), and helical tomotherapy (Tomo). The prescribed doses of 40-50 Gy in 10 fractions and 30 Gy in 10 fractions were simultaneously delivered to the metastatic lesions and the whole-brain volume, respectively. The hippocampal dose met the RTOG 0933 criteria for hippocampal avoidance (Dmax ≤17 Gy, D100% ≤10 Gy). The inner ear dose was restrained to Dmean ≤15 Gy. Target coverage (TC), homogeneity index (HI), conformity index (CI), maximum dose (Dmax), minimum dose (Dmin) and dose to organs at risk (OARs) were compared.

RESULTS

All plans met the indicated dose restrictions. The mean percentage of planning target volume of metastases (PTVmets) coverage ranged from 97.1 to 99.4%. For planning target volume of brain (PTVbrain), Tomo provided the lowest average D2% (37.5 ± 2.8 Gy), the highest average D98% (25.2 ± 2.0 Gy), and the best TC (92.6% ± 2.1%) and CI (0.79 ± 0.06). The two fixed gantry IMRT modalities (step and shot, dynamic) provided similar PTVbrain dose homogeneity (both 0.76). Significant differences across the four approaches were observed for the maximum and minimum doses to the hippocampus and the maximum doses to the eyes, lens and optic nerves.

CONCLUSION

All four radiotherapy modalities produced acceptable treatment plans with good avoidance of the hippocampus and inner ear. Tomo obtained satisfactory PTVbrain coverage and the best homogeneity index.

TRIAL REGISTRATION

Clinicaltrials.gov, NCT03414944 . Registered 29 January 2018.

Survival and quality of life after whole brain radiotherapy with 3D conformal boost in the treatment of brain metastases

Background

Brain metastases are the most frequent intracranial neoplasms in adults. Although overall survival (OS) is an important endpoint in patients receiving radiotherapy, given their poor life expectancy in general, quality of life is becoming an increasingly useful endpoint. Objectives: to evaluate whole brain radiotherapy (WBRT) with 3D conformal boost in brain metastases patients with regard to OS and quality of life.

Methods

During April 2015-May 2017, a total of 35 patients with ≤5, previously untreated, inoperable brain metastases were included prospectively. All patients underwent WBRT followed by 3D conformal boost to the metastatic lesions. EORTC quality of life questionnaires QLQ-C30 and QLQ-BN20 were used at baseline and at end of treatment. The mean initial and final scores were compared using Student test. One-year OS with brain metastases was computed with Kaplan Maier method.

Results

Median survival with brain metastases was 4.43 months (0.73-78.53). The one-year OS for patients with one metastasis was 42% versus 15% for more than one (p<0.04). The presence of extracerebral metastases significantly decreased OS from 39% without extracerebral metastases to 19%. (p<0.05). Quality of life improved significantly in several functional domains: physical (48 vs 60.29), role functioning (28.1 vs 44.7), emotional (47.1 vs 80.2), global health status (40.9 vs 62.3). Symptom scores decreased significantly in most items, corresponding to an improvement in the symptom burden: headache (61.9 vs 0.9), nausea and vomiting (45.7 vs 7.1), visual disorder (26.3 vs 9.2), seizures (30.4 vs 0.9), motor dysfunction (46.6 vs 17.1). Symptom scores for fatigue and drowsiness increased significantly (51.1 vs 74.9, respectively 37.1 vs 70.4), indicating worsening of symptoms.

Conclusions

WBRT with 3D conformal boost is a feasible technique which improves quality of life in brain metastases patients. Since survival is limited, the assessment of quality of life is a good indicator of the treatment outcome.

Combined irradiation and targeted therapy or immune checkpoint blockade in brain metastases: toxicities and efficacy

Background

Targeted therapies (TT) and immune checkpoint inhibitors (ICI) are currently modifying the landscape of metastatic cancer management and are increasingly used over the course of many cancers treatment. They allow long-term survival with controlled extra-cerebral disease, contributing to the increasing incidence of brain metastases (BMs). Radiation therapy remains the cornerstone of BMs treatment (either whole brain irradiation or stereotactic radiosurgery), and investigating the safety profile of radiation therapy combined with TT or ICI is of high interest. Discontinuing an efficient systemic therapy, when BMs irradiation is considered, might allow systemic disease progression and, on the other hand, the mechanisms of action of these two therapeutic modalities might lead to unexpected toxicities and/or greater efficacy, when combined.

Patients and methods

We carried out a systematic literature review focusing on the safety profile and the efficacy of BMs radiation therapy combined with targeted agents or ICI, emphasizing on the role (if any) of the sequence of combination scheme (drug given before, during, and/or after radiation therapy).

Results

Whereas no relevant toxicity has been noticed with most of these drugs, the concomitant use of some other drugs with brain irradiation requires caution.

Conclusion

Most of available studies appear to advocate for TT or ICI combination with radiation therapy, without altering the clinical safety profiles, allowing the maintenance of systemic treatments when stereotactic radiation therapy is considered. Cognitive functions, health-related quality of life and radiation necrosis risk remain to be assessed. The results of prospective studies are awaited in order to complete and validate the above discussed retrospective data.

[Whole Brain Irradiation and Hypo-fractionation Radiotherapy for the Metastases in Non-small Cell Lung Cancer]

Up to 40% non-small cell lung cancer patients developed brain metastasis during progression. Multiple brain metastases are common in non-small cell lung cancer. The prognosis of brain metastasis is poor with median survival of less than 1 year. Radio therapy for brain metastases has gradually developed from whole brain radiotherapy (WBRT) to various radiation strategies. WBRT, surgery+WBRT, stereotactic radiotherapy+WBRT or WBRT with simultaneous integrated boost (SIB), etc. have better overall survival than those untreated patients. The damage of the cognitive function from WBRT has been realized recently, however, options of radiation strategies for long expected survival patients remain controversial. This paper will discuss different WBRT strategies and treatment side effects of non-small cell lung cancer with brain metastases.

EGFR as a Target for Glioblastoma Treatment: An Unfulfilled Promise

The receptor for epidermal growth factor (EGFR) is a prime target for cancer therapy across a broad variety of tumor types. As it is a tyrosine kinase, small molecule tyrosine kinase inhibitors (TKIs) targeting signal transduction, as well as monoclonal antibodies against the EGFR, have been investigated as anti-tumor agents. However, despite the long-known enigmatic EGFR gene amplification and protein overexpression in glioblastoma, the most aggressive intrinsic human brain tumor, the potential of EGFR as a target for this tumor type has been unfulfilled. This review analyses the attempts to use TKIs and monoclonal antibodies against glioblastoma, with special consideration given to immunological approaches, the use of EGFR as a docking molecule for conjugates with toxins, T-cells, oncolytic viruses, exosomes and nanoparticles. Drug delivery issues associated with therapies for intracerebral diseases, with specific emphasis on convection enhanced delivery, are also discussed.

Whole brain radiotherapy with adjuvant or concomitant boost in brain metastasis: dosimetric comparison between helical and volumetric IMRT technique

BACKGROUND

To compare and evaluate the possible advantages related to the use of VMAT and helical IMRT and two different modalities of boost delivering, adjuvant stereotactic boost (SRS) or simultaneous integrated boost (SIB), in the treatment of brain metastasis (BM) in RPA classes I-II patients.

METHODS

Ten patients were treated with helical IMRT, 5 of them with SRS after whole brain radiotherapy (WBRT) and 5 with SIB. MRI co-registration with planning CT was mandatory and prescribed doses were 30 Gy in 10 fractions (fr) for WBRT and 15Gy/1fr or 45Gy/10fr in SRS or SIB, respectively. For each patient, 4 "treatment plans" (VMAT SRS and SIB, helical IMRT SRS and SIB) were calculated and accepted if PTV boost was included in 95 % isodose and dose constraints of the main organs at risk were respected without major deviations. Homogeneity Index (HI), Conformal Index (CI) and Conformal Number (CN) were considered to compare the different plans. Moreover, time of treatment delivery was calculated and considered in the analysis.

RESULTS

Volume of brain metastasis ranged between 1.43 and 51.01 cc (mean 12.89 ± 6.37 ml) and 3 patients had double lesions. V95% resulted over 95 % in the average for each kind of technique, but the "target coverage" was inadequate for VMAT planning with two sites. The HI resulted close to the ideal value of zero in all cases; VMAT-SIB, VMAT-SRS, Helical IMRT-SIB and Helical IMRT-SRS showed mean CI of 2.15, 2.10, 2.44 and 1.66, respectively (optimal range: 1.5-2.0). Helical IMRT-SRS was related to the best and reliable finding of CN (0.66). The mean of treatment time was 210 s, 467 s, 440 s, 1598 s, respectively, for VMAT-SIB, VMAT-SRS, Helical IMRT-SIB and Helical IMRT-SRS.

CONCLUSIONS

This dosimetric comparison show that helical IMRT obtain better target coverage and respect of CI and CN; VMAT could be acceptable in solitary metastasis. SIB modality can be considered as a good choice for clinical and logistic compliance; literature's preliminary data are confirming also a radiobiological benefit for SIB. Helical IMRT-SRS seems less effective for the long time of treatment compared to other techniques.

Impact of whole brain radiation therapy on CSF penetration ability of Icotinib in EGFR-mutated non-small cell lung cancer patients with brain metastases: Results of phase I dose-escalation study

OBJECTIVES

Whole-brain radiation therapy (WBRT) and epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) are both treatment options for EGFR-mutated non-small cell lung cancer (NSCLC) patients with brain metastases. However, the dose-escalation toxicity and efficacy of combination therapy, and the effect of WBRT on cerebrospinal fluid (CSF) penetration of EGFR-TKIs are still unclear.

MATERIALS AND METHODS

EGFR-mutated NSCLC patients with brain metastases were enrolled in this study, and the cohorts were constructed with a 3+3 design. The patients received icotinib with escalating doses (125-625mg, tid), and the concurrent WBRT (37.5Gy/15f/3weeks) started a week later. The CSF penetration rates of icotinib were tested before, immediately after, and 4 weeks after WBRT, respectively. Potential toxicities and benefits from dose-escalation treatment were analyzed.

RESULTS

Fifteen patients were included in this study, 3 at each dose level from 125mg-375mg and 6 at 500mg with 3 occurred dose-limiting toxicities. The maximal tolerated dose of icotinib was 375mg tid in this combination therapy. There was a significant correlation between icotinib concentration in the CSF and plasma (R(2)=0.599, P<0.001). The CSF penetration rate of icotinib, from 1.2% to 9.7%, reached a maximum at 375mg (median, 6.1%). There was no significant difference for CSF penetration rates among the three test points (median, 4.1% vs. 2.8% vs. 2.8%, P=0.16). The intracranial objective response rate and median intracranial progression free survival are 80% and 18.9 months.

CONCLUSIONS

WBRT plus concurrent icotinib is well tolerated in EGFR-mutated NSCLC patients with brain metastases, up to an icotinib dose of 375mg tid. The icotinib CSF concentration seemed to have a potential ceiling effect with the dose escalation, and WBRT seemed to have no significant impact on CSF penetration of icotinib till 4 weeks after the treatment.

Whole-brain hippocampal sparing radiation therapy: Volume-modulated arc therapy vs intensity-modulated radiation therapy case study

The hippocampus is responsible for memory and cognitive function. An ongoing phase II clinical trial suggests that sparing dose to the hippocampus during whole-brain radiation therapy can help preserve a patient׳s neurocognitive function. Progressive research and advancements in treatment techniques have made treatment planning more sophisticated but beneficial for patients undergoing treatment. The aim of this study is to evaluate and compare hippocampal sparing whole-brain (HS-WB) radiation therapy treatment planning techniques using volume-modulated arc therapy (VMAT) and intensity-modulated radiation therapy (IMRT). We randomly selected 3 patients to compare different treatment techniques that could be used for reducing dose to the hippocampal region. We created 2 treatment plans, a VMAT and an IMRT, from each patient׳s data set and planned on the Eclipse 11.0 treatment planning system (TPS). A total of 6 plans (3 IMRT and 3 VMAT) were created and evaluated for this case study. The physician contoured the hippocampus as per the Radiation Therapy Oncology Group (RTOG) 0933 protocol atlas. The organs at risk (OR) were contoured and evaluated for the plan comparison, which included the spinal cord, optic chiasm, the right and left eyes, lenses, and optic nerves. Both treatment plans produced adequate coverage on the planning target volume (PTV) while significantly reducing dose to the hippocampal region. The VMAT treatment plans produced a more homogenous dose distribution throughout the PTV while decreasing the maximum point dose to the target. However, both treatment techniques demonstrated hippocampal sparing when irradiating the whole brain.