Dose de-intensified 3-day photon, proton, or brachytherapy: a nonrandomized controlled partial breast irradiation trial.

BACKGROUND: The optimal approach for partial breast irradiation (PBI) is unknown. We investigated a novel de-intensified 3-fraction PBI regimen for photons, protons, and brachytherapy. METHODS: A multicenter nonrandomized controlled trial with primary outcome of adverse cosmesis at 3 years versus pre-PBI. Eligibility criteria were ≥ age 50 years treated with breast-conserving surgery for node-negative estrogen receptor positive (ER+) invasive breast cancer or any ductal carcinoma in-situ (DCIS) measuring ≤ 2.5 cm. Photon and proton PBI were prescribed 21.9 Gy (RBE) and brachytherapy 21 Gy in 3 fractions. Radiotherapy technique and use of adjuvant endocrine therapy was selected at physician and patient discretion. RESULTS: Between June 17, 2015 and July 13, 2017, 161 eligible patients were treated with photons (56), protons (49), or brachytherapy (56). Median patient age was 66.8 years. 126 (78.3%) had invasive breast cancer (all ER+) and 35 (21.7%) had DCIS (88.6% ER+). 54.0% of patients with invasive breast cancer and 25.8% of patients with ER+ DCIS initiated and adhered to prescribed endocrine therapy. The proportion of patients with adverse cosmesis (by trained nurse assessment) was 14.5% at baseline, 2.3% at 3 years (difference -12.2%, 95% CI (-100%, -6.4%)). Adverse cosmesis at last-follow-up, with median follow-up 5 years, was 5.7% by nurse assessment, 5.6% by panel assessment of digital photographs, and 5.2% by patient self-report. There were no observed clinically meaningful changes in other patient reported outcomes, and just two grade 2 or higher adverse events, both grade 2, in the brachytherapy cohort. 5-year local recurrence-free and progression-free survival were 98.0% and 95.5%, respectively. There were no local recurrences amongst 60 patients with invasive breast cancer and Ki67 ≤ 13.25%. CONCLUSIONS: De-intensified 3-day PBI provided favorable disease control, tolerability, and cosmetic outcomes, meeting the pre-specified criteria for acceptability. This approach is an attractive option for small node-negative ER+ BC and DCIS patients. TRIAL REGISTRATION: ClinicalTrials.gov identifier NCT02453737.

Quality-of-Life Outcomes from NRG/NSABP B-39/RTOG 0413: Whole-breast Irradiation vs Accelerated Partial-breast Irradiation after Breast Conserving Surgery.

PURPOSE: NRG Oncology (NRG)/NSABP B-39/RTOG 0413 compared whole-breast irradiation (WBI) to accelerated partial-breast irradiation (APBI). APBI was not equivalent to WBI in local tumor control. Secondary outcome was Quality-of-life (QOL). METHODS: The QOL sub-study used validated self-report questionnaires including the Breast Cancer Treatment Outcome Scale (BCTOS) and SF-36 vitality scale. Assessments occurred: before randomization, at treatment completion (chemotherapy or radiotherapy), 4-weeks later, at 6-, 12-, 24-, and 36-months. Primary aims: cosmesis change equivalency (baseline to 3 years; a priori margin of equivalence 0.4 standard deviations) and fatigue change superiority (baseline to end-of-treatment (EOT)) for APBI vs WBI, by patient groups treated with or without chemotherapy when appropriate. RESULTS: From 3/21/05-5/25/09, 975 patients enrolled in this sub-study; 950 had follow-up data. APBI had 3-year cosmesis equivalent to WBI (95%CI,-0.0001-0.16; equivalence margin -0.22-0.22) in all patients. The APBI group without chemotherapy had less EOT fatigue (p = .011; mean score APBI 63 vs WBI 59); APBI group receiving chemotherapy had worse EOT fatigue (p = .011; APBI 43 vs WBI 49). The APBI group reported less pain (BCTOS) at EOT (WBI 2.29 vs APBI 1.97), but worse pain at 3-years (WBI 1.62 vs APBI 1.71). APBI patients reported greater convenience of care than with WBI and reported less symptom severity at EOT and 4-weeks later. CONCLUSION: Cosmetic outcomes were similar for APBI and WBI groups, with small statistically significant differences in other outcomes that varied over time. Differences in fatigue and other symptoms appeared to resolve by ≥ 6 months. APBI may be preferred by some patients, for whom extended treatment is burdensome.

Lymphedema Rates Following Axillary Lymph Node Dissection With and Without Immediate Lymphatic Reconstruction: A Prospective Trial.

BACKGROUND: Immediate lymphatic reconstruction (ILR) has been proposed to decrease lymphedema rates. The primary aim of our study was to determine whether ILR decreased the incidence of lymphedema in patients undergoing axillary lymph node dissection (ALND). METHODS: We conducted a two-site pragmatic study of ALND with or without ILR, employing surgeon-level cohort assignment, based on breast surgeons' preferred standard practice. Lymphedema was assessed by limb volume measurements, patient self-reporting, provider documentation, and International Classification of Diseases, Tenth Revision (ICD-10) codes. RESULTS: Overall, 230 patients with breast cancer were enrolled; on an intention-to-treat basis, 99 underwent ALND and 131 underwent ALND with ILR. Of the 131 patients preoperatively planned for ILR, 115 (87.8%) underwent ILR; 72 (62.6%) were performed by one breast surgical oncologist and 43 (37.4%) by fellowship-trained microvascular plastic surgeons. ILR was associated with an increased risk of lymphedema when defined as ≥10% limb volume change on univariable analysis, but not on multivariable analysis, after propensity score adjustment. We did not find a statistically significant difference in limb volume measurements between the two cohorts when including subclinical lymphedema (≥5% inter-limb volume change), nor did we see a difference in grade between the two cohorts on an intent-to-treat or treatment received basis. For all patients, considering ascertainment strategies of patient self-reporting, provider documentation, and ICD-10 codes, as a single binary outcome measure, there was no significant difference in lymphedema rates between those undergoing ILR or not. CONCLUSION: We found no significant difference in lymphedema rates between patients undergoing ALND with or without ILR.

Prompt Pain Relief From Bone Metastases: The Virtual Simulation Program.

Purpose: Rapid pain relief for patients with bone metastases can be a challenge due to the lengthy and complex radiation therapy workflow. The purpose of this study was to evaluate the time (in days) between initial radiation oncology consultation and start of palliative radiation treatment after implementing an alternative virtual simulation palliative workflow. Methods and Materials: Patients meeting strict criteria were selected for virtual simulation, which included only those with painful bone metastases who were recommended palliative radiation therapy using standard anterior-posterior/posterior-anterior or opposed lateral fields. A recent (within 30 days) diagnostic computed tomography (CT) scan clearly visualizing the target volume was required for treatment planning. For comparison, a reference group of 40 consecutive patients with bone metastases who underwent in-person CT simulation before virtual simulation implementation was reviewed. Results: Forty-five patients were treated for painful bone metastases as part of the virtual simulation program from May 2021 to October 2022. Regarding travel distance, 23 patients lived locally (<50 miles from the treatment center) and 22 patients were distant (≥50 miles from the treatment center). Average time from consultation to treatment for all patients undergoing virtual simulation was 3.7 days, compared with 7.5 days for patients undergoing in-person CT simulation (3.8 days sooner, on average; P ≤ .001). Before full implementation of the virtual simulation program, 5 eligible patients participated in a virtual simulation pilot from April 2021 to May 2021, in which each patient was contoured and planned on both a pre-existing diagnostic CT scan and a standard CT simulation scan. For virtual simulation-based plans, the average V90, V95, and V99 were 99.99%, 99.87%, and 96.70%. No significant planning target volume (PTV) coverage difference was found on subsequent in-person CT simulation scans. Conclusions: The virtual simulation program decreased the time from consultation to start of treatment by more than 50% for patients recommended palliative radiation therapy for painful bone metastases. This benefit was most significant for outpatients traveling ≥50 miles for treatment. Virtual simulation-based planning can be considered for patients anxious to proceed with radiation therapy quickly or in underserved settings with limited transportation options to regional treatment centers.

Physician- and Patient-Reported Outcomes of the MC1635 Phase 3 Trial of Ultrahypofractionated Versus Moderately Hypofractionated Adjuvant Radiation Therapy After Breast-Conserving Surgery.

PURPOSE: Our aim was to report physician- and patient-reported outcomes of patients with localized breast cancer treated with moderate versus ultrahypofractionated whole breast irradiation (WBI) after breast-conserving surgery (BCS). METHODS AND MATERIALS: Between February 2018 and February 2020, patients with localized breast cancer (pT0-3 pN0-1 M0) were offered participation in a phase 3 randomized clinical trial assessing adjuvant moderate hypofractionation (MHF) to 40 Gy in 15 fractions versus ultrahypofractionation (UHF) to 25 Gy in 5 fractions after BCS, with an optional simultaneously integrated boost. Toxicities, cosmesis, and quality of life were assessed at baseline, end of treatment (EOT), and 3 months, 1 year, 2 years, and 3 years from irradiation using validated metric tools. RESULTS: One hundred seven patients were randomized to MHF (n = 54) or UHF (n = 53) adjuvant WBI. The median follow-up was 42.8 months. Grade 2 radiation dermatitis was experienced by 4 patients (7.4%) in the MHF arm and 2 patients (3.7%) in the UHF arm at EOT (P = .726). No grade 3 or higher toxicities were observed. Deterioration of cosmesis by physician assessment was observed in 2 (6.7%) patients treated in the UHF arm and 1 (1.9%) patient treated in the MHF arm at EOT (P = .534), whereas at 3 months, only 1 (1.8%) patient treated in the MHF arm demonstrated deterioration of cosmesis (P = .315). At EOT, 91% and 94% of patients reported excellent/good cosmesis among those treated with MHF and UHF regimens, respectively (P = .550). At 3 months, more patients within the MHF arm reported excellent/good cosmesis compared with those in the UHF arm (100% vs 91%; P = .030). However, the difference in patient-reported cosmesis disappeared at the 1-, 2-, and 3-year time points. CONCLUSIONS: UHF WBI showed similar treatment-related late toxicities and similar provider-scored cosmesis compared with MHF radiation in patients treated adjuvantly after BCS.

Carbon Ion Radiotherapy: An Evidence-Based Review and Summary Recommendations of Clinical Outcomes for Skull-Base Chordomas and Chondrosarcomas.

Skull-base chordoma and chondrosarcoma are rare radioresistant tumors treated with surgical resection and/or radiotherapy. Because of the established dosimetric and biological benefits of heavy particle therapy, we performed a systematic and evidence-based review of the clinical outcomes of patients with skull-base chordoma and chondrosarcoma treated with carbon ion radiotherapy (CIRT). A literature review was performed using a MEDLINE search of all articles to date. We identified 227 studies as appropriate for review, and 24 were ultimately included. The published data illustrate that CIRT provides benchmark disease control outcomes for skull-base chordoma and chondrosarcoma, respectively, with acceptable toxicity. CIRT is an advanced treatment technique that may provide not only dosimetric benefits over conventional photon therapy but also biologic intensification to overcome mechanisms of radioresistance. Ongoing research is needed to define the magnitude of benefit, patient selection, and cost-effectiveness of CIRT compared to other forms of radiotherapy.

Pragmatic, Prospective Comparative Effectiveness Trial of Carbon Ion Therapy, Surgery, and Proton Therapy for the Management of Pelvic Sarcomas (Soft Tissue/Bone) Involving the Bone: The PROSPER Study Rationale and Design.

Surgical treatment of pelvic sarcoma involving the bone is the standard of care but is associated with several sequelae and reduced functional quality of life (QOL). Treatment with photon and proton radiotherapy is associated with relapse. Carbon ion radiotherapy (CIRT) may reduce both relapse rates and treatment sequelae. The PROSPER study is a tricontinental, nonrandomized, prospective, three-arm, pragmatic trial evaluating treatments of pelvic sarcoma involving the bone. Patients aged at least 15 years are eligible for inclusion. Participants must have an Eastern Cooperative Oncology Group Performance Status score of two or less, newly diagnosed disease, and histopathologic confirmation of pelvic chordoma, chondrosarcoma, osteosarcoma, Ewing sarcoma with bone involvement, rhabdomyosarcoma (RMS) with bone involvement, or non-RMS soft tissue sarcoma with bone involvement. Treatment arms include (1) CIRT (n = 30) delivered in Europe and Asia, (2) surgical treatment with or without adjuvant radiotherapy (n = 30), and (3) proton therapy (n = 30). Arms two and three will be conducted at Mayo Clinic campuses in Arizona, Florida, and Minnesota. The primary end point is to compare the 1-year change in functional QOL between CIRT and surgical treatment. Additional comparisons among the three arms will be made between treatment sequelae, local control, and other QOL measures.

Pilot/Phase II Trial of Hypofractionated Radiation Therapy to the Whole Breast Alone Before Breast Conserving Surgery.

Purpose: Our purpose was to report the results of a phase II trial of patients with breast cancer treated with hypofractionated whole breast radiation therapy (RT) before breast-conserving surgery (BCS). Methods and materials: Between 2019 and 2020, patients with cT0-T2, N0, M0 breast cancer were enrolled. Patients were treated with hypofractionated whole breast RT, 25 Gy in 5 fractions, 4 to 8 weeks before BCS. Pathologic assessment was performed using the residual cancer burden (RCB). Toxicities were assessed according to Common Terminology Criteria for Adverse Events (version 4). Quality of life was assessed with Patient-Reported Outcomes version of the Common Terminology Criteria for Adverse Events, The Breast Cancer Treatment Outcome Scale, Linear Analogue Self-Assessment, and Patient-Reported Outcomes Measurement Information System. Results: Twenty-two patients were enrolled. Median follow-up was 7.6 months (range, 0.2-16.8). Seven (32%) and 2 (9%) patients experienced grade 2+ or 3 toxicities, respectively. Overall quality of life Linear Analogue Self-Assessment and Patient-Reported Outcomes Measurement Information System did not change significantly from baseline (P = .21 and P = .72, respectively). There was no clinically significant change (≥1 point) in any of The Breast Cancer Treatment Outcome Scale domains. Only 1 (5%) patient experienced a clinical deterioration that corresponded to a "fair" outcome on the Harvard Cosmesis Scale. At pathologic evaluation, 14 (64%) patients had RCB-0 or RCB-I, including 3 (14%) patients with a pathologic complete response (RCB-0). Eight patients (36%) had RCB-II. No local or distant recurrences have been observed. Conclusions: Extremely hypofractionated whole breast RT before BCS is a feasible approach. There were low rates of toxicities and good cosmesis. Further investigation into this approach with RT before BCS is warranted.

Exploring the Biological and Physical Basis of Boron Neutron Capture Therapy (BNCT) as a Promising Treatment Frontier in Breast Cancer.

BNCT is a high LET radiation therapy modality that allows for biologically targeted radiation delivery to tumors while reducing normal tissue impacts. Although the clinical use of BNCT has largely been limited to phase I/II trials and has primarily focused on difficult-to-treat malignancies such as recurrent head and neck cancer and recurrent gliomas, recently there has been a renewed interest in expanding the use of BNCT to other disease sites, including breast cancer. Given its high LET characteristics, its biologically targeted and tumor specific nature, as well as its potential for use in complex treatment settings including reirradiation and widespread metastatic disease, BNCT offers several unique advantages over traditional external beam radiation therapy. The two main boron compounds investigated to date in BNCT clinical trials are BSH and BPA. Of these, BPA in particular shows promise in breast cancer given that is taken up by the LAT-1 amino acid transporter that is highly overexpressed in breast cancer cells. As the efficacy of BNCT is directly dependent on the extent of boron accumulation in tumors, extensive preclinical efforts to develop novel boron delivery agents have been undertaken in recent years. Preclinical studies have shown promise in antibody linked boron compounds targeting ER/HER2 receptors, boron encapsulating liposomes, and nanoparticle-based boron delivery systems. This review aims to summarize the physical and biological basis of BNCT, the preclinical and limited clinical data available to date, and discuss its potential to be utilized for the successful treatment of various breast cancer disease states.

Dosimetric Analysis of Axillary Lymph Node Coverage Using High Tangents in the Prone Position for Left-Sided Breast Cancers.

AIM/OBJECTIVE: Prone positioning is often used to reduce the dose to organs at risk during adjuvant breast irradiation. High tangents are used with supine treatments in patients with the low-volume nodal disease to increase nodal coverage while minimizing toxicities. Our study aims to evaluate nodal coverage for patients treated in the prone position with high tangents. MATERIALS AND METHODS: Our study analyzed the plans for 20 patients with early-stage, left-sided breast cancers treated at our institution from 2018 to 2019. All patients were treated in the prone position. Axillary nodal levels I-III were contoured, and treatment plans were generated using high tangents. The heart, bilateral lungs, and breast tissue were retrospectively contoured. All plans were evaluated to a dose of 42.4 Gy in 16 fractions. RESULTS: Level I lymph node levels had a mean coverage of 99% of the prescription dose (range: 98-100%). Similarly, level II coverage was approximately 88% (range: 65-100%). The mean coverage for level III was approximately 25% (range: 0-52%). The mean heart dose, mean lung volume receiving ≥20 Gy (V20) for the bilateral lungs, and ipsilateral V20 were 1.69 Gy, 1.64%, and 3.56%, respectively. CONCLUSION: Treating patients in the prone position with high tangents provides excellent coverage of axillary levels I and II, although there is minimal coverage of axillary level III. Prospective trials are needed to evaluate the clinical outcomes when treating patients with high tangents in the prone position.

Is breast conservation superior to mastectomy in early stage triple negative breast cancer?

PURPOSE: Compare overall survival (OS) and breast cancer-specific survival (BCSS) outcomes of breast conservative therapy (BCT) and mastectomy in a large cohort of patients with early-stage triple negative breast cancer (TNBC), using a propensity score-based matching approach. METHODS: Surveillance, Epidemiology, and End Results (SEER) database was used to study the role of RT in early stage TNBC. Primary end points were OS and BCSS. Cox proportional hazard regression models and Kaplan-Meier plots were used to generate the desired outcomes. Propensity score matching was done to minimize bias. RESULTS: 12,761 patients with T1-2N0M0 TNBC as their first malignancy were retrieved. Of these 7237 had lumpectomy with RT, and 5524 had mastectomy only. Age, race, marital status, tumor laterality, grade and stage, and receipt of chemotherapy were prognostic variables for OS and BCSS. Among 4848 matched subjects, the 5-year OS was significantly higher in patients with lumpectomy and RT (89%) compared to mastectomy alone (84.5%) (p-value <0.001). Similarly, BCSS was significantly higher in patients with lumpectomy and RT (93%) compared to mastectomy alone (91%) (p-value <0.001). On subgroup analysis, patients who are younger than 40 had similar survival outcomes after either mastectomy alone or lumpectomy with RT. However, those who are older than 60, have any grade or T stage had better survival outcomes with lumpectomy and RT. CONCLUSIONS: Overall, lumpectomy followed by RT is associated with better OS and BCSS compared to mastectomy in T1-2N0M0 TNBC patients. Further research is needed to determine the optimal treatment strategy for specific patient subgroups.

Parental leave policy information during residency interviews.

BACKGROUND: During interviews, medical students may feel uncomfortable asking questions that might be important to them, such as parental leave. Parental leave policies may be difficult for applicants to access without asking the program director or other interviewers. The goal of this study is to evaluate whether parental leave information is presented to prospective residents and whether medical students want this information. METHODS: Fifty-two program directors (PD's) at 3 sites of a single institution received a survey in 2019 to identify whether parental leave information is presented at residency interviews. Medical students received a separate survey in 2020 to identify their preferences. Fisher exact tests, Pearson χ2 tests and Cochran-Armitage tests were used where appropriate to assess for differences in responses. RESULTS: Of the 52 PD's, 27 responded (52%) and 19 (70%) indicated that information on parental leave was not provided to candidates. The most common reason cited was the belief that the information was not relevant (n = 7; 37%). Of the 373 medical students, 179 responded (48%). Most respondents (92%) wanted parental leave information formally presented, and many anticipated they would feel extremely or somewhat uncomfortable (68%) asking about parental leave. The majority (61%) felt that these policies would impact ranking of programs "somewhat" or "very much." CONCLUSIONS: Parental leave policies may not be readily available to interviewees despite strong interest and their impact on ranking of programs by prospective residents.

Initial Observation among Patients with Vestibular Schwannoma.

Introduction Vestibular schwannomas (VS) are slow growing tumors. Although there are a wide variety of available treatment options, these tumors are often initially observed. We aimed to establish the presenting symptoms and outcomes of patients treated with initial observation at our institution. Methods The medical records of patients with radiographically diagnosed VS were reviewed from 1989 to 2018. Actuarial estimates of radiographic tumor control and freedom of local therapy were calculated and compared using Cox regression analyses. Results A total of 360 patients were diagnosed with VS at our institution from 1989 through 2018 with a median age of 59.9 years. After radiographic diagnosis, 243 patients (67.5%) opted for initial observation. Local control at 1, 5, and 10 years was 91, 67, and 58%, respectively. On multivariable analysis, factors associated with shorter time to radiographic tumor progression included younger patient age ( p = 0.016) and tumors with an extracanalicular component ( p = 0.032). Regarding time until definitive treatment only larger baseline American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) tumor size predicted for earlier initiation of therapy ( p < 0.001), although this was restricted to tumors with an extracanalicular component ( p = 0.004), as opposed to purely internal auditory canal tumors ( p = 0.839). Conclusion Many patients who were initially observed continued to have satisfactory local control rates at 10 years. In patients with extracanalicular tumors, larger AAO-HNS tumor measurements were associated with earlier radiographic tumor progression and shorter time to local therapy, with 7 mm serving as a potential threshold value for extracanalicular tumors. Younger patients and tumors with primarily an extracanalicular portion may warrant closer observation.

Pre-diagnosis major life stressors and breast cancer outcomes.

PURPOSE: While the association between diagnosis of breast cancer and post-diagnosis psychological distress has been well documented, data regarding pre-diagnosis psychological distress in the breast cancer population are limited. Here, we assessed pre-diagnosis major life stressors and breast cancer outcomes, namely stage of disease and choice of surgery, in a single-center population. METHODS: Patients with newly diagnosed clinical stage 0-3 breast cancer seen at Mayo Clinic Florida between June 11, 2018, and October 7, 2019, were administered voluntary telephone surveys to assess major life stressors during the 24 months preceding their cancer diagnosis. Subsequent clinical outcomes of cancer stage at diagnosis and surgical treatment were obtained through retrospective chart review. Study subjects who had experienced major life stressors and those who had not were compared using Chi-square tests. RESULTS: Of 222 patients who were included, 51.3% reported experiencing a major life event before breast cancer diagnosis. 43.9% of these patients endorsed family-related stress. 21.1% had experienced multiple stressors. 1.8% described financial stress. Although more patients in the group with pre-diagnosis stress had carcinoma in situ (21.1% versus 13.0%, p = 0.11) and fewer had stage T1/T2 disease (64% versus 73.1%, p = 0.14) than in the group without stress, these differences were not statistically significant. More patients with pre-diagnosis stress chose mastectomy (34.2% versus 22.2%, p = 0.048). CONCLUSIONS: Psychological distress is prevalent prior to breast cancer diagnosis and may merit early intervention. While additional study in diverse populations is needed, current data suggest possible associations between pre-diagnosis psychological distress and surgical decision making, specifically mastectomy.

Mask-based immobilization in Gamma Knife stereotactic radiosurgery.

The Gamma Knife Icon (Elekta AB, Stockholm) is a cobalt-based stereotactic radiosurgery (SRS) unit to support the use of a thermoplastic mask in lieu of a rigid frame, using an onboard cone-beam CT (CBCT) and an intrafraction motion management system (IFMM). We retrospectively reviewed 124 patients treated with Gamma Knife SRS from January 2018 to December 2019 at our institution using a mask-based immobilization system. Patient and treatment characteristics were collected and summarized as well as interfraction shifts and treatment-related outcomes. This dataset includes 124 patients with an associated 358 intracranial tumors. Twenty-four patients presented with primary brain tumors, which included 14 meningiomas and 10 other histologies, with 100 patients having brain metastases. Sixty tumors were post-operative, while 298 were intact. The median dose for primary tumors was 25 Gy in 5 fractions. Median doses to metastases were 20 Gy in 1 fraction, 27 Gy in 3 fractions, and 25 Gy in 5 fractions. Median interfraction CBCT shifts were submillimeter. Median patient follow-up was 6.28 months. 91% of patients with metastases maintained local control. Our early clinical experience has demonstrated limited toxicity profiles and high patient tolerance, which suggests that mask-based Gamma Knife SRS provides a safe alternative option for frameless SRS. Patients with large target volumes where fractionation is preferred or with small target volumes in non-eloquent areas can be considered for this approach. Response rates are encouraging, and continued follow-up is necessary to investigate long-term control and survival.

Estimating the Number of Patients Eligible for Carbon Ion Radiotherapy in the United States.

PURPOSE: Carbon ion radiotherapy (CIRT) is an emerging radiotherapy modality with potential advantages over conventional photon-based therapy, including exhibiting a Bragg peak and greater relative biological effectiveness, leading to a higher degree of cell kill. Currently, 13 centers are treating with CIRT, although there are no centers in the United States. We aimed to estimate the number of patients eligible for a CIRT center in the United States. MATERIALS AND METHODS: Using the National Cancer Database, we analyzed the incidence of cancers frequently treated with CIRT internationally (glioblastoma, hepatocellular carcinoma, cholangiocarcinoma, locally advanced pancreatic cancer, non-small cell lung cancer, localized prostate cancer, soft tissue sarcomas, and specific head and neck cancers) diagnosed in the United States in 2015. The percentage and number of patients likely benefiting from CIRT was estimated with inclusion criteria from clinical trials and retrospective studies, and that ratio was applied to 2019 cancer statistics. An adaption correction rate was applied to estimate the potential number of patients treated with CIRT. Given the high dependency on prostate and lung cancers and the uncertain adoption of CIRT in those diseases, the data were then reanalyzed excluding those diagnoses. RESULTS: Of the 1 127 455 new cases of cancer diagnosed in the United States in 2015, there were 213 073 patients (18.9%) eligible for treatment with CIRT based on inclusion criteria. When applying this rate and the adaption correction rate to the 2019 incidence data, an estimated 89 946 patients (42.2% of those fitting inclusion criteria) are eligible for CIRT. Excluding prostate and lung cancers, there were an estimated 8922 patients (10% of those eligible for CIRT) eligible for CIRT. The number of patients eligible for CIRT is estimated to increase by 25% to 27.7% by 2025. CONCLUSION: Our analysis suggests a need for CIRT in the United States in 2019, with the number of patients possibly eligible to receive CIRT expected to increase during the coming 5 to 10 years.