Development and clinical implementation of simple needle attachment post placement interstitial template (SNAPP-IT) enabling a shorter, more direct needle path while preserving tumor visualization

PURPOSE

Historical gynecologic interstitial brachytherapy templates block direct tumor visualization during needle placement, presenting an opportunity for clinical innovation to develop a novel interstitial template allowing direct tumor visualization during needle insertion.

METHODS AND MATERIALS

We designed and implemented a novel interstitial template, simple needle attachment post placement interstitial template (SNAPP-IT), that allowed direct visualization of the target vaginal tumor during interstitial needle placement while maintaining the ability to individually secure needles to the template, allow a vaginal cylinder, suture holes for securing to the perineum, MRI compatibility and sterilizable for repeat use. Procedure outcomes including procedure time, needle path lengths, and plan dosimetry were prospectively captured in a patient database.

RESULTS

Forty gynecologic interstitial brachytherapy cases were recorded (20 SNAPP-IT, 20 traditional templates). Needle insertion depth was reduced using the SNAPP-IT in comparison with traditional interstitial templates (11.8 cm vs. 3.6 cm, p < 0.0001). The average CTV volume was 25.6 cc for SNAPP-IT and 20.7 cc for traditional; both methods averaged a similar number of needles (15.8, 15.6). Dosimetric constraints were similarly met in both treatment groups. Procedures performed using the SNAPP-IT were shorter compared with those performed with traditional interstitial devices (83.4 minutes vs. 100.7 minutes) and there were no post-operative infections in the SNAPP-IT group.

CONCLUSIONS

Implementation of a novel gynecologic interstitial brachytherapy template (SNAPP-IT) reduced procedure times, allowed direct tumor visualization, and decreased needle insertion depth. SNAPP-IT provides a useful alternative approach for vaginal interstitial brachytherapy, may increase brachytherapist efficiency with complex procedures and potentially expands access to interstitial brachytherapy.

Effects of Wildfire Events on California Radiation Oncology Clinics and Patients

Purpose

The effect of climate-driven events, such as wildfires, on health care delivery and cancer care is a growing concern. Patients with cancer undergoing radiation therapy are particularly vulnerable to treatment interruptions, which have a direct effect on survival. We report the results of a study characterizing the effect of wildfires on radiation oncology clinics and their patients.

Methods and Materials

A survey of California radiation oncologists was used to evaluate emergency preparedness and the effect of wildfires on the delivery of radiation therapy services between 2017 and 2022. Descriptive statistics and Pearson's χ2 tests were performed to investigate potential relationships between provider characteristics, practice settings, and perceptions of the effect of wildfire events. California Department of Forestry and Fire Protection data were employed to map the geographic distribution of wildfires to clinic locations.

Results

Response rate was 12.3% (51/415 radiation oncologists), representing 25% of clinics (43/176) in 41% (24/58) of California counties. Sixty-one percent (31/51) of respondents reported being affected by a wildfire, 2 of which are rural clinics (100%, 2/2) and 29 are (59%, 29/49) metropolitan practices. Of these, 18% (9/51) reported a clinic closure, and 29% (15/51) reported staffing shortages. Respondents reported effects on patients, including having to evacuate (55%, 28/51), cancel/reschedule treatments (53%, 27/51), and experiencing physical, mental, or financial hardship due to wildfires (45%, 23/51). Respondents described effects on clinical operations, including being forced to transfer patients (24%, 12/51), transportation interruptions (37%, 19/51), regional/community evacuations (35%, 18/51), and physical/mental health effects (27%, 14/51) on clinic personnel. Less than half of the respondents (47%, 24/51) reported their workplace had a wildfire emergency preparedness plan. Additionally, geographic analysis revealed that 100% (176/176) of clinics were located within 25 miles of a wildfire.

Conclusions

This study highlights the effects of wildfires on radiation oncology clinics and patients and underscores the need for emergency preparedness planning to minimize the consequences of such disasters.

Safety of Radiation Therapy for Treatment of Malignancy in Patients with Inflammatory Bowel Disease

PURPOSE/OBJECTIVE(S)

Inflammatory bowel disease (IBD) has been considered a relative contraindication to radiation therapy (RT) due to the potential greater risk of RT-induced toxicities, however, there is limited toxicity data using modern RT techniques. This study aims to assess toxicity outcomes in patients with IBD treated with abdominal or pelvic RT.

MATERIALS/METHODS

After institutional review board approval, patients with IBD who received RT to the abdomen or pelvis were filtered from an institutional research repository and their electronic medical records were reviewed. Acute toxicity was defined as that occurring within 3 months of RT. Toxicities were graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events version 5.0. Univariable Cox proportional hazards regression was used to assess rates of grade ≥2 toxicity-free survival.

RESULTS

We identified 62 patients with median age of 69 years (interquartile range [IQR] 62-77) who received RT from 2006-2022. Median follow up was 15 months (IQR 4-33). Most patients were male (42; 68%) and had a diagnosis of ulcerative colitis (44; 71%). The most common primary malignancy was colorectal/anal (26; 42%). Intensity-modulated RT (IMRT) was most frequently used (38; 61%) followed by 3-dimensional conformal RT (3D-CRT) (12; 19%) and stereotactic body RT (SBRT)/brachytherapy (12; 19%). For IMRT/3D-CRT, median dose delivered was 50 Gy (IQR 49-59) in 25 fractions (IQR 25-30), and median maximum dose (Dmax) to bowel was 48 Gy (IQR 43-52); whereas for SBRT/brachytherapy, the median dose was 32 Gy (IQR 27-40) in 3 fractions (IQR 2-5) and median bowel Dmax was 32 Gy (IQR 20-37). The median biologically effective dose delivered with an assumed alpha/beta ratio of 10 (BED10) across all RT modalities was 63 Gy (IQR 60-72). After initiation of RT, 31 patients (50%) and 14 patients (23%) experienced grade ≥2 acute and late toxicity, respectively. Thirteen patients (21%) and 7 patients (11%) experienced grade 3 acute and late toxicity, respectively. No patients experienced grade >3 toxicity. Acute toxicity resulted in interruption to RT for 5 patients (8%), 2 of which did not resume RT. Four patients (6%) required adjustment to chemotherapy or IBD medication dosage as a result of their acute toxicity. Median time from RT start to acute toxicity onset was 41 days (IQR 32-46), whereas median time to onset of late toxicity was 9 months (IQR 5-15). The most common acute and late toxicities were diarrhea (21; 34%) and bowel obstruction/perforation/fistula (4; 6%), respectively. Rates of grade ≥2 toxicity-free survival overtime were not significantly associated with IBD status (active vs quiescent), delivered BED10, or bowel Dmax BED3.

CONCLUSION

In patients with IBD treated with abdominal or pelvic RT for malignancy, RT was feasible with acceptable rates of toxicity and active versus quiescent IBD status did not impact toxicity outcomes. Future research is needed to elucidate specific dose constraints when treating patients with IBD.

Low Dose Splenic Radiotherapy for Myeloproliferative Neoplasms prior to Allogeneic Hematopoietic Stem Cell Transplant

PURPOSE/OBJECTIVE(S)

Myeloproliferative neoplasms including primary and secondary myelofibrosis (MF) are a rare spectrum of chronic myeloproliferative disorders in which nearly 90% of patients experience splenomegaly. Importantly, splenic radiotherapy (SRT) may be used in combination with allogeneic stem cell transplant (alloSCT) to improve symptoms related to splenomegaly, though there currently is no consensus SRT dose/fractionation protocol reported in the literature for use in combination with alloSCT. We sought to report our institutional experience utilizing low dose SRT prior to alloSCT in the post-Jakafi era.

MATERIALS/METHODS

We performed a retrospective review of all patients diagnosed with MF at our institution from 2017-2022 who received reduced intensity alloHCT. Patients who underwent total lymphoid or body irradiation were excluded. Descriptive demographic and clinical characteristics of patients were summarized by means, medians, standard deviations, ranges and proportions as appropriate.

RESULTS

We identified 39 patients with MF who underwent reduced intensity conditioning (RIC) consisting of fludarabine/melphalan in preparation for alloHCT (median age 64.5, 12/16 males, median follow up 21 months). 16 patients with Jakafi-resistant splenomegaly completed low dose SRT prior to transplant (median spleen size: 24.5cm) with a median dose of 5Gy delivered in 5 fractions. 3D conformal therapy was used for all patients. All patients completed the planned total radiation course without treatment break or dose limiting acute toxicity. Thrombocytopenia was the most reported toxicity (CTCAE v5.0; 2 patients experienced grade 1, 1 patient experienced grade 2). No patients experienced grade 3 or higher acute cytopenias nor required transfusion during radiotherapy. All patients successfully received alloHCT a median of 7 days (range: 2-11) after the completion of SRT with a 94% (15/16) engraftment rate. Median neutrophil recovery (ANC > 500 × 3 days) time was 18 days (range: 13-31); median length of hospital stay was 23 days (range: 20-129). Overall survival was 75% in the SRT cohort (12/16, 2 with persistent disease, 2 due to other causes). Symptom burden data was available for 14/16 patients; 79% (11/14) of patients reported improvement in symptoms associated with splenomegaly or reduction in splenic size on physical examination.

CONCLUSION

In the largest reported experience of a low dose SRT only cohort to date, we observe low dose SRT is feasible, safe in combination with alloHCT with high engraftment rates, and may reduce symptoms related to splenomegaly thereby improving patient quality of life without compromising transplant related outcomes. A prospective study validating this protocol is currently underway.

Impacts of Wildfire Events on California Radiation Oncology Clinics and Patients

PURPOSE/OBJECTIVE(S)

The impact of climate-related disasters such as wildfires on healthcare delivery and cancer care is a growing concern. Patients undergoing radiotherapy are particularly vulnerable to treatment interruptions which are known to have a direct impact on survival outcomes. We report results of the first pilot study characterizing the impact of wildfires on radiation oncology clinics and their patients.

MATERIALS/METHODS

A survey was sent to 415 California radiation oncologists representing 144 clinics identified using the ASTRO member directory to gather information about clinic and radiation oncologist demographics, wildfires' impacts on the clinic (physical/operational), physicians, staff, and patients between 2017 and 2022, as well as clinics' disaster preparedness efforts.

RESULTS

A total of 51 radiation oncologists completed the survey, representing 43 clinics (30% of clinics) in 24 (41%) of California counties. 35 (69%) of respondents self-identified as male, 27 (53%) worked at hospital-affiliated centers, 19 (37%) worked in academic centers, with 49 (96%) practicing in metropolitan areas. A total of 31 clinics were impacted by a wildfire between 2017 and 2020. The two rural clinics (100%) and 29 (59%) of metro practices reported being impacted by wildfires in the last 5 years, with 9 (18%) reporting a clinic closure and 15 (29%) reporting staffing shortages. 28 (55%) of respondents reported impacts on patients including having to evacuate, 27 (53%) having to cancel or reschedule treatments, and 23 (45%) experiencing physical, mental, or financial hardship due to the wildfires. Among the 25 clinics impacted by wildfires, 12 (24%) reported physical/operational impacts including being forced to evacuate patients to another treatment center, transportation interruptions (19, 37%), community and regional evacuations (18, 35%), school closures (18, 35%), and physical/mental health impacts (14, 27%) on staff due to the wildfires. Small clinics (25 staff or less) that experienced a wildfire were twice as likely to experience closures (6 of 16 clinics, 38%) but equally likely to experience staffing shortages (8 of 16, 50 %) as compared to larger practices (7 of 15, 47%). Nearly half of respondents 25 (47%) reported their workplace had a wildfire emergency preparedness plan.

CONCLUSION

The results of this study demonstrate the significant impact wildfires have on patient care in both rural and metropolitan areas. The findings emphasize the importance of emergency preparedness planning to minimize the consequences of such disasters and underscores the need for further research to explore risk factors associated with patient and community vulnerability to climate-related crises. Such research will be essential to informing and developing future emergency preparedness plans.

Effect of Radiation Schedule on Transportation-Related Carbon Emissions: A Case Study in Rectal Cancer

Purpose

The health care sector is a major contributor of worldwide greenhouse gas (GHG) emissions. Indirect emissions, including those associated with transportation, make up 82% of the US health care sector's environmental footprint. Radiation therapy (RT) treatment regimens present an opportunity for environmental health care-based stewardship owing to the high incidence of cancer diagnosis, significant utilization of RT, and myriad treatment days required for curative regimens. Because the use of short-course RT (SCRT) in the treatment of rectal cancer has demonstrated noninferior clinical outcomes compared with conventional, long-course RT (LCRT), we investigate the environmental and health equity-related outcomes.

Methods and Materials

Patients treated with curative, preoperative RT for newly diagnosed rectal cancer at our institution between 2004 and 2022 and living in-state were included. Travel distance was estimated using patients' reported home address. Associated GHG emissions were calculated and reported in carbon dioxide equivalents (CO₂e).

Results

Of 334 patients included, the total distance traveled for the treatment course was significantly greater in patients treated with LCRT versus SCRT (median, 1417 vs 319 miles; P < .001). Total CO₂e emissions for those undergoing LCRT (n = 261) and SCRT (n = 73) were 665.3 kg CO₂e and 149.9 kg CO₂e, respectively, per treatment course (P < .001), with a net difference of 515.4 kg CO₂e. Relatively, this suggests that LCRT is associated with 4.5 times greater GHG emissions from patient transportation.

Conclusions

Using treatment of rectal cancer as proof-of-principle, we advocate for the inclusion of environmental considerations in the creation of climate-resilient oncologic RT practices, especially in the context of equivocal clinical outcomes between RT fractionation schedules.

SUPPORT: SUrvey of Parental Leave POlicies of RadiaTion Oncology Programs and Residency Applicants

Purpose

Recruitment to radiation oncology training programs has recently declined, and gender inequities persist in radiation oncology. Policies that promote inclusivity, such as the updated American College of Graduate Medical Education parental leave policy establishing minimum parental leave requirements, may support recruitment to radiation oncology.

Methods and Materials

We surveyed 2021-2022 radiation oncology residency applicants and program directors (PDs) about program-specific parental leave policies, transparency of parental leave information during the residency application and interview process, and perceptions of the effect of parenthood on residency training, career advancement, and well-being.

Results

Of 89 radiation oncology PDs, 29 (33%) completed the survey. Of 154 residency applicants (current fourth-year medical students, international applicants, or postdoctoral fellows) surveyed, 62 (40%) completed the survey. Most applicants planned to start a family during residency (53%) and reported perceived flexibility to start a family influenced their decision to pursue radiation oncology over other career specialties (55%). Many applicants viewed time in residency (nonresearch, 22%), in research (33%), and as early career faculty (24%) as the best time to start a family. A small number of applicants used program-specific parental leave policy information in determining their rank list (11%), and many applicants sought information regarding fertility health care benefits (55%). Many applicants obtained parental leave information verbally, despite expressing a preference for objective means (slide deck, 63%; website, 50%; or handout, 42%) of information sharing. PDs were all supportive of a 6-week maternity leave policy (100% agree or strongly agree with the policy) and did not feel parental leave would negatively affect a resident's ability to pursue an academic (100%) or private practice career (100%).

Conclusions

Many radiation oncology residency applicants plan to start families during training, seek and value program-specific parental leave information and health benefits, and prefer objective means of information sharing. These findings likely reflect those who have strong views of parental leave policies.

Paraneoplastic Neurologic Symptoms in a Pediatric Patient with Hodgkin Lymphoma

Neurological paraneoplastic syndromes are exceedingly rare, and often difficult to recognize clinically. Paraneoplastic achalasia is a condition characterized by new-onset dysphagia that is unrelated to tumor burden, most often due to the development of auto-immune antibodies targeting esophageal tissue. Due to the rarity of this condition, diagnosis is often delayed, leading to increased time to treatment. Here we report a case of a rare paraneoplastic achalasia in a female child with EBV + Hodgkin lymphoma (HL), review literature describing paraneoplastic achalasia, and discuss treatment strategies for improving clinical outcome in these patients.

Intratumoral injection reduces toxicity and antibody-mediated neutralization of immunocytokine in a mouse melanoma model

Background

Some patients with cancer treated with anticancer monoclonal antibodies (mAbs) develop antidrug antibodies (ADAs) that recognize and bind the therapeutic antibody. This response may neutralize the therapeutic mAb, interfere with mAb effector function or cause toxicities. We investigated the potential influence of ADA to modify the tumor-binding capability of a tumor-reactive ‘immunocytokine’ (IC), namely, a fusion protein (hu14.18-IL2) consisting of a humanized, tumor-reactive, anti-GD2 mAb genetically linked to interleukin 2. We characterize the role of treatment delivery of IC (intravenous vs intratumoral) on the impact of ADA on therapeutic outcome following IC treatments in an established antimelanoma (MEL) regimen involving radiotherapy (RT) +IC.

Methods

C57BL/6 mice were injected with human IgG or the hu14.18-IL2 IC to develop a mouse anti-human antibody (MAHA) response (MAHA⁺). In vitro assays were performed to assess ADA binding to IC using sera from MAHA⁺ and MAHA⁻ mice. In vivo experiments assessed the levels of IC bound to tumor in MAHA⁺ and MAHA⁻ mice, and the influence of IC route of delivery on its ability to bind to B78 (GD2+) MEL tumors.

Results

MAHA is inducible in C57BL/6 mice. In vitro assays show that MAHA is capable of inhibiting the binding of IC to GD2 antigen on B78 cells, resulting in impaired ADCC mediated by IC. When B78-bearing mice are injected intravenously with IC, less IC binds to B78-MEL tumors in MAHA⁺ mice than in MAHA⁻ mice. In contrast, when IC is injected intratumorally in tumor-bearing mice, the presence of MAHA does not detectibly impact IC binding to the tumor. Combination therapy with RT+IT-IC showed improved tumor regression compared with RT alone in MAHA⁺ mice. If given intratumorally, IC could be safely readministered in tumor-bearing MAHA⁺ mice, while intravenous injections of IC in MAHA⁺ mice caused severe toxicity. Histamine levels were elevated in MAHA⁺ mice compared with MAHA⁻ mice after reintroduction of IC.

Conclusions

Intratumoral injection may be a means of overcoming ADA neutralization of therapeutic activity of tumor-reactive mAbs or ICs and may reduce systemic toxicity, which could have significant translational relevance.

In situ Vaccine Plus Checkpoint Blockade Induces Memory Humoral Response

In a syngeneic murine melanoma (MEL) model, we recently reported an in situ vaccination response to combined radiation (RT) and intra-tumoral (IT) injection of anti-GD2 hu14. 18-IL2 immunocytokine (IC). This combined treatment resulted in 71% complete and durable regression of 5-week tumors, a tumor-specific memory T cell response, and augmented response to systemic anti-CTLA-4 antibody checkpoint blockade. While the ability of radiation to diversify anti-tumor T cell response has been reported, we hypothesize that mice rendered disease-free (DF) by a RT-based ISV might also exhibit a heightened B cell response. C57BL/6 mice were engrafted with 2 × 10⁶ GD2+ B78 MEL and treated at a target tumor size of ~200 mm³ with 12 Gy RT, IT-IC on day (D)6-D10, and anti-CTLA-4 on D3, 6, and 9. Serum was collected via facial vein before tumor injection, before treatment, during treatment, after becoming DF, and following rejection of subcutaneous 2 × 10⁶ B78 MEL re-challenge on D90. Flow cytometry demonstrated the presence of tumor-specific IgG in sera from mice rendered DF and rejecting re-challenge with B78 MEL at D90 after starting treatment. Consistent with an adaptive endogenous anti-tumor humoral memory response, these anti-tumor antibodies bound to B78 cells and parental B16 cells (GD2-), but not to the unrelated syngeneic Panc02 or Panc02 GD2+ cell lines. We evaluated the kinetics of this response and observed that tumor-specific IgG was consistently detected by D22 after initiation of treatment, corresponding to a time of rapid tumor regression. The amount of tumor-specific antibody binding to tumor cells (as measured by flow MFI) did not correlate with host animal prognosis. Incubation of B16 MEL cells in DF serum, vs. naïve serum, prior to IV injection, did not delay engraftment of B16 metastases and showed similar overall survival rates. B cell depletion using anti-CD20 or anti-CD19 and anti-B220 did not impact the efficacy of ISV treatment. Thus, treatment with RT + IC + anti-CTLA-4 results in adaptive anti-tumor humoral memory response. This endogenous tumor-specific antibody response does not appear to have therapeutic efficacy but may serve as a biomarker for an anti-tumor T cell response.

Combining brachytherapy and immunotherapy to achieve in situ tumor vaccination: A review of cooperative mechanisms and clinical opportunities

As immunotherapies continue to emerge as a standard component of treatment for a variety of cancers, the imperative for testing these in combination with other standard cancer therapies grows. Radiation therapy may be a particularly well-suited partner for many immunotherapies. By modulating immune tolerance and functional immunogenicity at a targeted tumor site, radiation therapy may serve as a method of in situ tumor vaccination. In situ tumor vaccination is a therapeutic strategy that seeks to convert a patient's own tumor into a nidus for enhanced presentation of tumor-specific antigens in a way that will stimulate and diversify an antitumor T cell response. The mechanisms whereby radiation may impact immunotherapy are diverse and include its capacity to simultaneously elicit local inflammation, temporary local depletion of suppressive lymphocyte lineages, enhanced tumor cell susceptibility to immune response, and immunogenic tumor cell death. Emerging data suggest that each of these mechanisms may display a distinct dose-response profile, making it challenging to maximize each of these effects using external beam radiation. Conversely, the highly heterogenous and conformal dose distribution achieved with brachytherapy may be optimal for enhancing the immunogenic capacity of radiation at a tumor site while minimizing off-target antagonistic effects on peripheral immune cells. Here, we review the immunogenic effects of radiation, summarize the clinical rationale and data supporting the use of radiation together with immunotherapies, and discuss the rationale and urgent need for further preclinical and clinical investigation specifically of brachytherapy in combination with immunotherapies. Harnessing these immunomodulatory effects of brachytherapy may offer solutions to overcome obstacles to the efficacy of immunotherapies in immunologically "cold" tumors while potentiating greater response in the context of immunologically "hot" tumors.