A randomized trial evaluating a novel hydrogel packing system compared to standard packing during image-guided high-dose rate brachytherapy boost for cervical cancer

INTRODUCTION

The purpose of this prospective randomized trial was to compare the use of a novel vaginal hydrogel packing system (BrachyGel) to standard vaginal packing (VP) during high dose rate (HDR) brachytherapy (BT) for locally advanced cervical cancer (LACC).

METHODS

This cross-over study included LACC patients receiving HDR BT boost (intracavitary +/- interstitial). All patients received alternating gauze or BrachyGel VP on Arms A and B. Patients, physicians, and physicists evaluated BT characteristics via a 4-point Likert scale. Adverse events (AEs) were prospectively collected and scored per CTCAE.

RESULTS

The 20 patients enrolled. The mean bladder D2cc difference between gauze and BrachyGel in Arm A was 0.117 Gray (Gy) and in Arm B 0.013 Gy. The mean difference in rectum D2cc in Arm A and Arm B was -0.189 Gy and -0.191 Gy, respectively. The mean dose to 90% of the high-risk clinical target volume (HR-CTV) for gauze compared to BrachyGel was -0.032 Gy (95% CI: 0.472, 0.409). Patient-reported discomfort was similar with BrachyGel and gauze ("mild/moderate" 70.0% vs 74.0%, respectively). The clarity of VP was similar between BrachyGel and gauze (86.8% vs 89.7%, respectively). The completeness of VP was more frequently "excellent/good" with BrachyGel (79.0%) compared to gauze (56.4%). The ease of packing was more frequently "extremely easy" with BrachyGel (21.2% vs 0%). No serious AEs were reported.

CONCLUSION

This randomized trial found no clinically significant difference in OAR or HR-CTV dosimetry between BrachyGel and standard VP. BrachyGel performed well compared to gauze for the patient and physician use experience.

Evaluating the relationship between vaginal apex "dog ears" and patterns of recurrence in endometrial cancer following adjuvant image guided vaginal cuff brachytherapy

PURPOSE

The aim of this investigation is to characterize vaginal apex "dog ears" and their association with patterns of treatment failure in patients with endometrial cancer treated with adjuvant high-dose-rate (HDR) single-channel vaginal cuff brachytherapy (VCB).

METHODS

A retrospective review of patients treated with HDR VCB from 2012 to 2021 for medically operable endometrial cancer at a single institution was conducted. Dog ears, defined as tissue at the apex extending at least 10 mm from the brachytherapy applicator were identified on CT simulation images. Fisher exact test and a multivariate logistic regression model evaluated the association between factors of interest with treatment failure. Vaginal cuff failure free survival (VCFFS) was calculated from first brachytherapy to vaginal cuff recurrence (VCR).

RESULTS

A total of 219 patients were reviewed. In this sample, 57.5% of patients met criteria for having dog ears. In total, 13 patients (5.9%) developed a VCR. There was no statistically significant difference in the rate of VCR between patients with and without dog ears (7.1% vs. 4.3%, p = 0.56). There was a trend toward increased risk of recurrence with higher grade histology identified in the multivariate logistic regression model (p = 0.085). The estimated 3-year probability of VCFFS was 86%.

CONCLUSIONS

Vaginal apex dog ears are prevalent but are not found to statistically increase the risk of VCR after VCB in our single institution experience. However, while local failure remains low in this population, we report an absolute value of over twice as many VCRs in patients with dog ears, indicating that with improved dog ear characterization this may remain a relevant parameter for consideration in treatment planning.

The impact of viral etiology in yttrium-90–treated hepatocellular carcinoma

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Background: Hepatocellular carcinoma (HCC) is the most common type of liver cancer and is derived from a background of chronic inflammation from both viral and environmental factors. Recent data indicates that immune therapy efficacy is improved in virally mediated HCC. We sought to investigate what impact HCC etiology has on outcomes in patients treated with yttrium-90 (Y90). Methods: We conducted a retrospective review of patients with HCC treated at our institution with Y90 radiotherapy from 2005-2021. Clinical and treatment characteristics were recorded, including: age, stage, HCC etiology, performance status, Child Pugh class, liver mass/volume treated, dose, prior therapy, imaging characteristics and basic labs. Univariable (UVA) and multivariable analyses (MVA) were conducted to identify prognostic factors for local control (LC) and overall survival (OS) following Y90. Results: 67 patients and 196 distinct tumors treated with Y90 were identified. Median prescription dose was 110 Gy (range 44-157). Patients were stage I-IVB with the most frequent stages being II, IIIb and IIIa (34%, 21% and 19% patients, respectively). 49 patients (73%) were Child-Pugh A and 18 (27%) were Child-Pugh B. 5 patients only had hepatitis B (7%), 26 patients only had hepatitis C (39%), and 6 patients had both hepatitis B and C (9%). Median OS among all patients was 7.6 (95% CI 5.6-11.5) months following Y90. The LC rate of all treated lesions was 42% and 24% at 6 and 12 months, respectively. On UVA analysis, improved LC was associated with younger age ( p=0.019), smaller liver mass ( p=0.039), and Hepatitis B etiology ( p=0.018). On Cox regression survival analysis, worsened OS was associated with lower ECOG status ( p=0.024), advanced stage ( p=0.023), lower albumin ( p=0.001), higher AFP ( p<0.001), and portal vein invasion/thrombosis ( p=0.006, p=0.010). On MVA, lower albumin, higher AFP, advance stage and prior sorafenib were significantly related to worsened OS. If hepatitis B or C was forced into the MVA, the hazard ratio was 0.6 (95% CI 0.3-1.04) with p=0.068. Conclusions: Our results indicate that viral etiology impacts LC in our patients. Larger studies are necessary to confirm these results and to determine whether viral etiology impacts OS.

Para-Aortic Nodal Radiation in the Definitive Management of Node-Positive Cervical Cancer

Objectives

To investigate the safety and outcomes of elective para-aortic (PA) nodal irradiation utilizing modern treatment techniques for patients with node positive cervical cancer.

Methods

Patients with pelvic lymph node positive cervical cancer who received radiation were included. All patients received radiation therapy (RT) to either a traditional pelvic field or an extended field to electively cover the PA nodes. Factors associated with survival were identified using a Cox proportional hazards model, and toxicities between groups were compared with a chi-square test.

Results

96 patients were identified with a mean follow up of 40 months. The incidence of acute grade ≥ 2 toxicity was 31% in the elective PA nodal RT group and 15% in the pelvic field group (Chi-square p = 0.067. There was no significant difference in rates of grade ≥ 3 acute or late toxicities between the two groups (p>0.05). The KM estimated 5-year OS was not statistically different for those receiving elective PA nodal irradiation compared to a pelvic only field, 54% vs. 73% respectively (log-rank p = 0.11).

Conclusions

Elective PA nodal RT can safely be delivered utilizing modern planning techniques without a significant increase in severe (grade ≥ 3) acute or late toxicities, at the cost of a possible small increase in non-severe (grade 2) acute toxicities. In this series there was no survival benefit observed with the receipt of elective PA nodal RT, however, this benefit may have been obscured by the higher risk features of this population. While prospective randomized trials utilizing a risk adapted approach to elective PA nodal coverage are the only way to fully evaluate the benefit of elective PA nodal coverage, these trials are unlikely to be performed and instead we must rely on interpretation of results of risk adapted approaches like those used in ongoing clinical trials and retrospective data.

Normal tissue dose and risk estimates from whole and partial breast radiation techniques

PURPOSE

To compare radiation dose to organs at risk in patients with early-stage breast cancer treated with lumpectomy and intraoperative radiation therapy with CT-guided HDR brachytherapy (precision breast IORT; PB-IORT) and those treated with external beam whole breast irradiation (WB-DIBH) or partial breast irradiation (PB-DIBH) with deep inspiratory breath hold.

METHODS

We retrospectively identified 52 consecutive patients with left-sided breast cancers treated with either PB-IORT (n = 17, 76% outer breast) on a phase I clinical trial, adjuvant PB-DIBH (n = 18, 56% outer breast, 6% cavity boost), or WB-DIBH (n = 17, 76% outer breast, 53% with lumpectomy cavity boost). Conventional (2 Gy/fraction) or moderate hypofractionation (2.66 Gy/fraction) was prescribed for the external beam cohorts and 12.5 Gy in 1 fraction to 1 cm from the balloon surface was prescribed to the HDR brachytherapy cohort. CT-based planning was used for all patients. Organ at risk doses and excess risk ratios (ERR) for secondary lung cancers, contralateral breast cancers, and cardiac toxicity were compared between treatment techniques.

RESULTS

Compared to WB-DIBH and PB-DIBH, PB-IORT resulted in lower ipsilateral lung V5, V10, V20, mean, and max dose (P < .05). Mean ipsilateral lung BED_3Gy was as follows: 1.32 Gy for PB-IORT, 4.33 Gy for WB-DIBH, 3.35 Gy for PB-DIBH. The ERR for lung cancer was lowest for PB-IORT (P < .001). There was significantly higher contralateral breast max dose but lower mean BED_3Gy for WB-DIBH compared with PB-IORT (P = .012, P = .011, respectively). Mean contralateral breast BED_3Gy was as follows: 0.10 Gy for PB-IORT, 0.06 Gy for WB-DIBH, and 0.08 Gy for PB-DIBH. The ERR for contralateral breast cancer was low for all breast techniques, but WB-DIBH showed lower ERR compared to PB-IORT (P = .019). Mean heart BED_2Gy was higher with PB-IORT at 1.26 Gy compared to 0.48 Gy and 0.24 Gy for WB-DIBH and PB-DIBH, respectively (P < .001).

CONCLUSIONS

Patients with early-stage breast cancer treated with PB-IORT and with tissue-sparing external beam techniques all received low organ at risk doses, but PB-IORT resulted in far lower ipsilateral lung dose compared with external beam techniques. Our data indicate the lowest mean contralateral breast BED in the WB-DIBH group, likely due to the simplicity of the field design in low-risk patients using tangential whole breast radiation. External beam using DIBH results in lowest heart dose, but all techniques were well within recommended heart constraints.

The vaginal cylinder: Misunderstood, misused, or trivial? An in-depth dosimetric and multiinstitutional outcome investigation

PURPOSE

The purpose of the study was to investigate the impact on dose distribution and radiobiological metrics of common high-dose-rate vaginal brachytherapy treatment parameters and to analyze multiinstitutional data for clinically significant impact on outcomes in early-stage endometrial cancer.

METHODS AND MATERIALS

Treatment plans were created for all combinations of prescription parameters and used to quantify the dosimetric impact of each parameter and to estimate the dose delivered using common voxel-integrated radiobiological metrics. A rating system, based on risk grouping from GOG and PORTEC trials, was used to consolidate staging information into a cancer "aggressiveness" measure. Correlations between the rating, toxicity, disease recurrence, and plan parameters were investigated.

RESULTS

When prescribing to 5 mm depth, the variation caused by the diameter was very large across all dose metrics, ranging from 51% to 175% increase with the most divergence in BED_max. For surface prescription, changing the cylinder diameter from 4 cm to 2 cm caused the dose metrics of BED_min, D_min, and gBEUD (a = -3) to increase by 117%, 67%, and 52%, respectively. Prescription to 5-mm depth caused changes across all dose metrics of 260% compared with surface prescription for a 2-cm cylinder. Deeper prescription point (p = 0.005) and longer treatment length (p = 0.01) were correlated with increased stenosis rates. No correlation between recurrence and any plan parameter was found.

CONCLUSIONS

Dramatic differences in dose distributions arise by small variations of plan parameters, with large impact on rates of vaginal stenosis, but no clear relation with local recurrence. To help radiation oncologists interpret the magnitude of these effects for their patients, we created a tool that allows comparison between dose and fractionation parameters.

Preliminary toxicity results using partial breast 3D-CRT with once daily hypo-fractionation and deep inspiratory breath hold

BACKGROUND

To evaluate the clinical outcomes of patients treated with 3D conformal Hypo-fractionated, deep Inspiratory breath-hold (DIBH), Partial breast radiotherapy, termed "HIP." HIP was implemented to merge the schedule of once-daily breast hypofractionation with partial breast treatment.

METHODS

We identified 38 breast cancers in 37 patients from 2013 to 2014 treated at our institution with HIP following lumpectomy for early stage breast cancer. Patients received a hypo-fractionated course (≤ 20 fractions) of once daily radiation to the partial breast (lumpectomy cavity + margin) utilizing DIBH regardless of laterality. Clinical and treatment-related characteristics were obtained, including target volume and organ at risk (OAR) dosimetric characteristics. Patients were followed clinically and with at least yearly mammograms for up to 36 months (range 5-36 months). Acute and late toxicity was scored using the Common Terminology Criteria for Adverse Events (CTCAE) v4.03.

RESULTS

Patients received a median dose of 42.56 Gy in 16 Fractions (Fx) (range 40.05-53.2 Gy; and 15-20 Fx). OAR doses were low, with a mean heart dose of 0.37 Gy, an ipsilateral lung V20 mean of 4%, and a contralateral lung V5 of 1%. Acute toxicity (≤ grade 2) was present in 79% (n = 30) of the cases, with dermatitis being the most common finding (63%). Late grade 1-2 toxicity was present in 42% (n = 16) of the cases, with hyperpigmentation being the most common finding (n = 9). There were no severe acute or late toxicities (≥ grade 3). At a median follow up of 21 months, there were no local, regional, or distant failures.

CONCLUSIONS

We report limited toxicity in this low risk cohort of patients with early stage breast cancer treated with HIP, a unique and logical combination of 3-D conformal external beam radiotherapy, moderate hypo-fractionation, and DIBH.

High dose-rate tandem and ovoid brachytherapy in cervical cancer: dosimetric predictors of adverse events

Background

Brachytherapy (BT) is a vital component of the curative treatment of locally advanced cervical cancer. The American Brachytherapy Society has published guidelines for high dose rate (HDR) BT with recommended dose limits. However, recent reports suggest lower doses may be needed to avoid toxicity. The purpose of this study is to investigate incidence and predictive factors influencing gastrointestinal (GI) and genitourinary (GU) toxicity following HDR intracavitary brachytherapy for locally advanced cervical cancer.

Methods

We retrospectively evaluated a cohort of patients with locally advanced cervical cancer who received CT-based HDR BT. Cumulative doses were calculated using the linear-quadratic model. Statistical analyses were used to investigate clinical and dosimetric predictors of GI and GU toxicity following HDR brachytherapy according to CTCAE v4.0 grading criteria.

Results

Fifty-six women with FIGO IB1 – IVA cervical cancer were included. The overall rate of any GU adverse event (Grade 1+) was 23.3% (n = 13) and severe adverse events (Grade 3+) was 7.1% (n = 4). Of those, the bladder equivalent dose in 2- Gray (Gy) fractions (EQD₂) D_2cc was ≥80 for three of the four patients. The overall rate of any GI adverse event was 26.8% (n = 15) and the rate of severe adverse events was 14.3% (n = 8). Of those, six of the eight patients had a rectal EQD₂ D_2cc ≥ 65 Gy and seven patients had a sigmoid D2cc ≥ 65 Gy. Amongst clinically meaningful factors for development of adverse events (i.e. diabetes, smoking status, ovoid size, and treatment duration), there were no statistically significant prognostic factors identified.

Conclusions

Severe adverse events are observed even with adherence to current ABS guidelines. In the era of recent multi-institutional study results, our data also supports more stringent dosimetric goals. We suggest cumulative D2cc dose limits of: less than 80 Gy for the bladder and less than 65 Gy for the rectum and sigmoid.

Integration of MRI target delineation into rapid workflow cervical cancer brachytherapy: Impact on clinical outcomes

INTRODUCTION

We evaluated the impact of MRI-based target delineation on toxicity and tumour control after implementation of a protocol to incorporate MRI while minimizing impact on overall procedural time.

METHODS

We retrospectively reviewed outcomes for a cohort of 96 consecutive patients who received intracavitary brachytherapy for cervical cancer at our institution during 2012-2016. Starting in October 2014, an outpatient MRI was obtained for patients after Smit sleeve placement and first insertion to assess concurrent chemoradiotherapy tumour response. Then, for subsequent fractions, the MRI was co-registered by the Smit sleeve to the planning CT for target volume delineation. The primary and secondary outcomes were toxicity and local control, respectively.

RESULTS

Median follow-up for the pre- (n = 50) and post-MRI-based (n = 46) planning groups was 24.6 and 14.7 months, respectively. Median treatment duration for patients before and after MRI implementation was 56 and 58 days (P = 0.052), respectively. Cumulative rectal D2 cc was less for those with MRI-based target delineation (P = 0.005). On multivariable analysis, patients with MRI-based target delineation experienced fewer severe late (CTCAE grade ≥ 3) toxicities (P = 0.025, hazard ratio = 0.25). Local control was 86% and 91% of the pre- and post-MRI groups, respectively (P = 0.959).

CONCLUSIONS

Preliminary findings using this technique, which is applicable to other institutions without in-room MRI availability, are associated with lower radiation prescription doses, lower rectal doses and favourable toxicity rates while maintaining a rapid workflow. Longer follow-up is required to confirm equivalent local control.

The Effect of Receptor Status on Mastectomy and Contralateral Prophylactic Mastectomy Rates in Early Stage Invasive Breast Carcinoma

BACKGROUND

There is an established relationship between hormone receptor (HR; estrogen and/or progesterone receptors) status, HER2 status, and locoregional recurrence. The purpose of this study was to analyze how HR and HER2 receptor status have influenced the surgical management trends among patients with early stage breast cancer.

PATIENTS AND METHODS

The National Cancer Database was queried for patients with cT1 to cT3, cN0, and cM0 breast carcinoma from 2004 to 2012. Patients were grouped on the basis of receptor status and surgical management (mastectomy or breast-conserving surgery [BCS]). Multivariable analyses were performed to investigate factors associated with increased odds of receiving mastectomy over BCS. Among a subgroup of patients who underwent ipsilateral mastectomy, analyses were performed to determine any association between contralateral prophylactic mastectomy (CPM) and receptor status.

RESULTS

We found 280,241 patients who met inclusion criteria for analyzing mastectomy or BCS surgical decision. Patients with HER2-positive (HER2⁺) tumors (HR⁺/HER⁺ and HR^-/HER2⁺) were the most likely to undergo mastectomy (odds ratio [OR], 1.212 and 1.499 respectively, compared with HR⁺/HER2^- patients, each P < .001). HR status alone did not affect ipsilateral surgical management as patients with HR⁺/HER2^- and HR^-/HER2^- tumors demonstrated similar mastectomy rates (P = .391). Among the 108,018 who underwent mastectomy, 20% underwent CPM. After adjustment, patients with HR⁺/HER2⁺, HR^-/HER2⁺, and HR^-/HER2^- were all more likely to undergo CPM (OR 1.356, 1.608, and 1.358, respectively compared with HR⁺/HER2^- patients, each P < .001).

CONCLUSION

This analysis indicates that patients with early stage breast cancer are more likely to undergo a mastectomy and CPM if they have HER2⁺ tumors.

Clinical outcomes of helical conformal versus nonconformal palliative radiation therapy for axial skeletal metastases

PURPOSE

Palliative radiation therapy (RT) for bone metastases has traditionally been delivered with conventional, nonconformal RT (NCRT). Conformal RT (CRT) is potentially more complex and expensive than NCRT, but may reduce normal tissue dose and subsequently toxicity. In this retrospective analysis, we compared CRT with NCRT to investigate the association between conformality and toxicity.

METHODS AND MATERIALS

A retrospective analysis of patients receiving palliative RT for axial skeletal bone metastases from 2012 to 2014 was conducted. Patient and treatment characteristics were obtained including dosimetric variables, acute toxicity, and subjective pain during treatment and in the acute posttreatment period (≤60 days after completion). Statistical analyses included t tests, χ² tests, and multivariate logistic regression.

RESULTS

A total of 179 patients and 254 bone metastases were identified (142 CRT, 112 NCRT). The CRT and NCRT groups were well matched for baseline characteristics (number of fractions, field size, treatment sites, and concurrent chemotherapy). In multivariate logistic regression models, technique (CRT vs NCRT) was not associated with development of acute toxicity. Regarding toxicity, Eastern Cooperative Oncology Group performance status and total dose were significantly associated with a higher rate of acute toxicity during RT (odds ratios, 0.649 and 1.129 and P = .027 and .044, respectively), and only a higher number of vertebral bodies in the treatment field was significantly associated with acute toxicity post-treatment (odds ratios, 1.219, P = .028). CRT was associated with improvement in bone pain during and posttreatment (P = .049 and .045, respectively).

CONCLUSIONS

Our results demonstrate no difference in acute toxicity following palliative RT with CRT compared with NCRT for painful bone metastases; however, treatment volume did predict for increased toxicity. Larger studies may further elucidate the value of CRT including the impact of dose escalation for bone metastases and differences in patient reported outcomes between RT techniques.

Choosing a Prescription Isodose in Stereotactic Radiosurgery for Brain Metastases: Implications for Local Control

OBJECTIVE

Stereotactic radiosurgery (SRS) achieves excellent local control (LC) with limited toxicity for most brain metastases. SRS dose prescription variables influence LC; therefore, we evaluated the impact of prescription isodose line (IDL) on LC after SRS.

METHODS

A retrospective analysis of patients with brain metastases treated on a Gamma Knife platform from 2004 to 2014 was conducted. Clinical, toxicity, radiographic, and dosimetric data were collected. Cox proportional hazards regression was used to determine progression-free survival (PFS) and competing risks analysis was used to determine predictive factors for LC.

RESULTS

A total of 134 patients with 374 brain metastases were identified with a median survival of 8.7 months (range, 0.2-64.8). The median tumor maximum dimension was 8 mm (range, 2-62 mm), median margin dose was 20 Gy (range, 5-24 Gy), and 12-month LC rate was 88.7%. On multivariate analysis, PFS improved with increasing IDL (P = 0.003) and decreased with non-non-small-cell lung cancer histology (P = 0.001). Margin dose, tumor size, conformality, and previous whole-brain irradiation failed to independently affect PFS. When adjusting for death as a competing risk, the cumulative likelihood of LC improved with higher IDL (P = 0.04). The rate of SRS-induced radiographic and clinical toxicity was low (16.6% and 1.5%, respectively), and neither was affected by IDL.

CONCLUSIONS

Our results confirm that SRS for brain metastases results in favorable LC, particularly for patients with smaller tumors. We noted that dose delivery to a higher prescription IDL is associated with small but measurable improvements in LC. This finding could be related to higher dose just beyond the radiographically apparent tumor.

Accelerated partial breast irradiation with brachytherapy: patient selection and technique considerations

Accelerated partial breast irradiation (APBI) through breast brachytherapy is a relatively recent development in breast radiotherapy that has gained international favor because of its reduction in treatment duration and normal tissue irradiation while maintaining favorable cancer-specific and cosmetic outcomes. Despite the fact that several large national trials have not reported final results yet, many providers are currently offering APBI to select patients and APBI is listed as a treatment option for selecting patients in the National Comprehensive Cancer Network guidelines. Multiple consensus guidelines exist in selecting patients for APBI, some with conflicting recommendations. In this review, the existing patient selection guidelines are reported, compared, and critiqued, grouping them in helpful subcategories. Unique patient and technical selection factors for APBI with brachytherapy are explored.

Leptomeningeal disease following stereotactic radiosurgery for brain metastases from breast cancer

Leptomeningeal disease (LMD) is a highly aggressive and usually rapidly fatal condition. The purpose of this study is to identify clinical factors that can serve to predict for LMD at the time of stereotactic radiosurgery (SRS) for brain metastases from breast carcinoma. We conducted a retrospective review of patients with brain metastases from breast cancer treated with SRS from 1995 to 2014 at our institution. Clinical, radiographic, and dosimetric data were collected. LMD was diagnosed by cerebrospinal fluid (CSF) cytology or MRI demonstrating CSF seeding. Comparative statistical analyses were conducted using Cox proportional hazards regression, binary logistic regression, and/or log-rank test. 126 patients met inclusion criteria. Eighteen patients (14 %) developed LMD following SRS. From the time of SRS, the actuarial rate of LMD at 12 months from diagnosis of brain metastasis was 9 % (11 patients). Active disease in the chest at the time of SRS was associated with development of LMD (p = 0.038). Factors including receptor status, tumor size, number of intra-axial tumors, cystic tumor morphology, prior WBRT, active bone metastases, and active liver metastases were not significantly associated with the development of LMD. In patients with brain metastasis from breast cancer that undergo SRS, there is a relatively low rate of LMD. We found that while tumor hormonal status, bone metastases, and hepatic metastases were not associated with the development of LMD, active lung metastases at SRS was associated with LMD. Further research may help to delineate a causative relationship between metastatic lung disease and LMD.