Quality of life in patients with chordomas/chondrosarcomas during treatment with proton beam therapy

Post-treatment late and long-term effects in bone sarcoma: A scoping review

Despite the fact that chemotherapy for bone sarcomas (e.g. Ewing sarcoma, osteosarcoma) has well-reported toxicities and that surgical intervention is frequently life altering, follow-up care to monitor for late and long-term effects beyond that of oncological surveillance in former patients is variable. Anecdotal evidence suggests that inconsistent follow-up means some former bone sarcoma patients are left to cope with post-treatment late and long-term effects with limited support. Here, we performed a scoping review to provide a more empirical identification of the knowledge gaps and to provide an overview of the peer reviewed academic literature reporting the late and long-term effects of treatment for bone sarcoma. JBI Scoping Review Network guidelines for charting, analysis and data extraction were followed. Literature searches were conducted in Medline (Ovid), Cochrane CENTRAL, EMBASE (Ovid), CINAHL, PsycINFO, Proquest and Web of Science (Clarivate Analytics) from March 2024 to September 2024. Paper titles and abstracts were screened by two independent reviewers followed by full text analysis by the lead researcher. Seventy-four peer reviewed articles were included in the analysis. Most studies were of a retrospective study design, some up to 20 years of follow-up and included chemotherapy, surgery and sometimes radiotherapy as the treatment modality. Our analysis identified secondary malignancies, cardio- and nephrotoxicity, lower bone mineral density and microarchitectural deterioration, cancer related fatigue and motor neuropathies as the major physical late and long-term effects requiring dedicated follow-up. In some cases, follow-up may need to span decades, especially given the increasing population of former patients. Our results form the evidence-based foundations for future work that might include late and long-term effect follow-up service mapping exercises and expanded clinical recommendations.

Proton Radiation Therapy for Head and Neck Cancers

Head and neck (HnN) cancers are among the most common cancers in the world. Proton therapy (PT) is one of the latest advancements in the treatment modalities of cancers. Proton therapy is specifically used to treat HnN cancer patients due to its less toxic effects on the surrounding critical structures. Keeping in view the opportunities for further advancements, there is a lot of literature covering PT in HnN cancer patients. However, few compiled studies are not enough to compare the toxicities, overall survival (OS), local control (LC), and quality of life (QoL) of PT with that of intensity-modulated radiation therapy (IMRT). The objective of this review is to compile and summarize the literature available on the toxicities, OS, LC, and QoL in HnN cancer patients post PT. We have gathered and summarized the literature found under the keyword "proton therapy for head and neck cancers". Proton therapy is a preferable option over IMRT because it isolates tumors of the HnN, reduces exposure of healthy cells to radiation, and allows accurate tumor scanning using the pencil beam technique. In view of this article, we can say that PT is a preferable mode of radiotherapy for HnN cancer patients in view of its accuracy and lower incidents of acute and late toxicities.

Radiotherapy After Gross Total Resection of Skull Base Chordoma: A Surveillance, Epidemiology, and End Results Database Analysis of Survival Outcomes

OBJECTIVE

Skull base chordoma is a rare and locally destructive malignancy which presents unique therapeutic challenges. While achieving gross total resection (GTR) confers the greatest survival advantage, the role of adjuvant radiotherapy (RT) for patients who receive GTR remains unclear in the absence of prospective trials. Here, we aim to assess the effect of RT on survival outcomes in skull base chordoma patients who receive GTR by utilizing the Surveillance, Epidemiology, and End Results (SEER) database.

METHODS

Patients with diagnostic, primary site, and resection codes specific for chordoma, skull base, and GTR, respectively, were queried in the SEER database (2000-2018). Kaplan-Meier curves (log-rank test) were constructed and Cox proportional hazards models were used to assess survival outcomes.

RESULTS

A total of 115 skull base chordomas undergoing GTR were identified, of which 37 (32%) received no RT and 78 (68%) received RT. Median follow-up was 55.00 months (range: 0.00-227.00). Overall survival (OS) of patients with GTR was 85% and 70% at 5 and 10 years, respectively. Multivariate Cox proportional hazard analysis among chordoma patients undergoing GTR found age ≥65 (P < 0.01) was associated with poorer OS outcomes. RT appeared to trend toward offering benefit in terms of OS in patients after GTR, however this did not achieve statistical significance in the adjusted model (HR = 0.51, CI = 0.23-1.16, P = 0.09). When comparing, disease-specific survival was also not improved in patients undergoing RT (HR = 0.58, CI = 0.23-1.46, P = 0.25).

CONCLUSIONS

It remains unclear whether RT after GTR of chordoma improved survival outcomes among SEER database patients.

Patient, Disease, and Treatment-Related Factors Affecting Progression-Free and Disease-Specific Survival in Recurrent Chondrosarcomas of the Skull Base

BACKGROUND

Recurrent skull base chondrosarcomas (CSA) are difficult to treat, and limited data are available to help guide subsequent therapy.

OBJECTIVE

To further characterize the natural history of CSA and identify treatment modalities that were most effective in prolonging progression-free (PFS) and disease-specific survival (DSS).

METHODS

We conducted a single-institution retrospective review of patients with recurrent skull base CSA from 1993 to 2021. Kaplan-Meier survival analyses for PFS and DSS were completed. Univariable and multivariable Cox proportional hazards regression models were used to identify patient-related, treatment-related, and disease-related factors that predicted PFS and DSS.

RESULTS

A total of 28 patients and 84 episodes of recurrence were included. One-year PFS was 70.6%, 5-year PFS was 28.9%, and 10-year DSS was 78.5%. The median time to first progression was 23.9 months (range, 2.8-282 months). In univariable Cox proportional hazards regression, male sex, higher grade histology, fourth or greater progression episode status, distal pattern of recurrence, and treatment of recurrence without surgery or with chemotherapy alone predicted worse PFS. Multivariable regression predicted shortened DSS in male patients (hazard ratio [HR] 0.16; P = .021) and higher-grade tumors (HR 0.22; P = .039). Treatment of recurrence with surgery was associated with, but did not significantly predict, improved DSS (HR 1.78; P = .11).

CONCLUSION

Several patient and disease-specific factors were associated with shorter PFS and DSS in recurrent skull base chondrosarcoma. For recurrences amenable to resection, surgery is recommended for treatment of recurrent CSA. Local recurrence management without surgery results in shorter PFS and DSS.

Financial toxicity in sarcoma patients and survivors in Germany: results from the multicenter PROSa study

Purpose

Cancer patients have been shown to frequently suffer from financial burden before, during, and after treatment. However, the financial toxicity of patients with sarcoma has seldom been assessed. Therefore, the aim of this study was to evaluate whether financial toxicity is a problem for sarcoma patients in Germany and identify associated risk factors.

Methods

Patients for this analysis were obtained from a multicenter prospective cohort study conducted in Germany. Using the financial difficulties scale of the EORTC QLQ-C30, financial toxicity was considered to be present if the score exceeded a pre-defined threshold for clinical importance. Comparisons to an age- and sex-matched norm population were performed. A multivariate logistic regression using stepwise backward selection was used to identify factors associated with financial toxicity.

Results

We included 1103 sarcoma patients treated in 39 centers and clinics; 498 (44.7%) patients reported financial toxicity. Sarcoma patients had 2.5 times the odds of reporting financial difficulties compared to an age- and sex-matched norm population. Patient age < 40 and > 52.5 years, higher education status, higher income, and disease progression (compared to patients with complete remission) were associated with lower odds of reporting financial toxicity. Receiving a disability pension, being currently on sick leave, and having a disability pass were statistically significantly associated with higher odds of reporting financial toxicity.

Conclusion

Financial toxicity is present in about half of German sarcoma patients, making it a relevant quality of life topic for patients and decision-makers.

The Role of Plan Robustness Evaluation in Comparing Protons and Photons Plans - An Application on IMPT and IMRT Plans in Skull Base Chordomas

PURPOSE

To analyze robustness of treatment plans optimized using different approaches in intensity modulated proton therapy (IMPT) and investigate the necessity of robust optimization and evaluation in intensity modulated radiotherapy (IMRT) plans for skull base chordomas.

MATERIALS AND METHODS

Two photon plans, standard IMRT and robustly optimized IMRT (RB-IMRT), and two IMPT plans, robustly optimized multi field optimization (MFO) and hybrid-MFO (HB-MFO), were created in RayStation TPS for five patients previously treated using single field uniform optimization (SFO). Both set-up and range uncertainties were incorporated during robust optimization of IMPT plans whereas only set-up uncertainty was used in RB-IMRT. The dosimetric outcomes from the five planning techniques were compared for every patient using standard dose volume indices and integral dose (ID) estimated for target and organs at risk (OARs). Robustness of each treatment plan was assessed by introducing set-up uncertainties of ±3 mm along the three translational axes and, only in protons, an additional range uncertainty of ±3.5%.

RESULTS

All the five nominal plans provided comparable and clinically acceptable target coverage. In comparison to nominal plans, worst case decrease in D95% of clinical target volume-high risk (CTV-HR) were 11.1%, 13.5%, and 13.6% for SFO, MFO, and HB-MFO plans respectively. The corresponding values were 13.7% for standard IMRT which improved to 11.5% for RB-IMRT. The worst case increased in high dose (D1%) to CTV-HR was highest in IMRT (2.1%) and lowest in SFO (0.7%) plans. Moreover, IMRT showed worst case increases in D1% for all neurological OARs and were lowest for SFO plans. The worst case D1% for brainstem, chiasm, spinal cord, optic nerves, and temporal lobes were increased by 29%, 41%, 30%, 41% and 14% for IMRT and 18%, 21%, 21%, 24%, and 7% for SFO plans, respectively. In comparison to IMRT, RB-IMRT improved D1% of all neurological OARs ranging from 5% to 14% in worst case scenarios.

CONCLUSION

Based on the five cases presented in the current study, all proton planning techniques (SFO, MFO and HB-MFO) were robust both for target coverage and OARs sparing. Standard IMRT plans were less robust than proton plans in regards to high doses to neurological OARs. However, robust optimization applied to IMRT resulted in improved robustness in both target coverage and high doses to OARs. Robustness evaluation may be considered as a part of plan evaluation procedure even in IMRT.

Unravelling the heterogeneity of soft tissue and bone sarcoma patients' health-related quality of life: a systematic literature review with focus on tumour location

Patients with sarcoma experience many physical and psychological symptoms, adversely affecting their health-related quality of life (HRQoL). HRQoL assessment is challenging due to the diversity of the disease. This review aims to unravel the heterogeneity of HRQoL of patients with sarcoma with regard to tumour location and to summarise the used measures in research. English-language literature from four databases published between January 2000 and April 2019 was reviewed. Studies that described adult sarcoma HRQoL outcomes were included and classified according to primary sarcoma location. Eighty-seven articles met the inclusion criteria covering sarcoma of the extremities (n=35), pelvis and axial skeleton (n=9), pelvis and extremities (n=5), head and neck (n=4), retroperitoneum (n=2) and multiple sarcoma locations (n=33), respectively. Urogenital and thoracic sarcoma were lacking. Fifty-four different questionnaires were used, most often cancer-generic or generic HRQoL questionnaires. Patients with sarcoma reported lower HRQoL than the general population. Distinctive patterns of HRQoL outcomes according to tumour location regarding symptoms, physical functioning, disability and psychosocial well-being were identified. In metastatic sarcoma, mostly constitutional symptoms were present. To comprehensively assess HRQoL, a sarcoma-specific measurement strategy should be developed and used covering the heterogeneity of sarcoma including location-specific issues to improve personalised HRQoL assessment in future research and clinical practice.

Child Proton Beam Therapy: A qualitative study of parental views on treatment and information sources

INTRODUCTION

Proton Beam Therapy (PBT) is often described as an advanced mode of radiotherapy. Whilst PBT offers an equivalent chance of cure to conventional radiotherapy, it is said to offer a theoretical reduction in long term side effects. NHS patients have had access to PBT since 2008 and approximately 65% of the 1144 approved referrals have been for paediatric cases. Yet, there is little research on how parents in these paediatric cases perceive their child's PBT and the information sources they encounter.

METHODS

This is a qualitative inquiry informed by in-depth interviews carried out with 27 parents of children treated with PBT.

RESULTS

Parents primarily frame PBT as a form of radiation but one which is better than alternatives. Whilst medical professionals do play a role, wider sources of information - such as other families and the internet - are important to both initial decision-making and treatment/recovery experiences.

CONCLUSION

Parents are faced with the challenge of a 'fragmented expertise' which comes with the 'novelty' of the radiation therapy, the 'rare' nature of the tumours and the remote location of clinical specialists.

IMPLICATIONS FOR PRACTICE

This article will prove useful for practitioners dealing with parents and care givers of children undergoing proton therapy, and is especially valuable and timely for practitioners based in the newly installed proton centres in the UK. Two high energy proton centres are expected to become fully operational in the UK by the end of 2020. Understanding parents' experiences and perspectives can help avoid undue anxiety and lead to service improvements and overall satisfaction.

Patient's quality of life after surgery and radiotherapy for extremity soft tissue sarcoma - a retrospective single-center study over ten years

Background and objectives

The purpose of this study is to analyze major complication rates and different aspects of health-related quality of life (HRQoL) in extremity soft tissue sarcoma (STS) patients treated with or without radio (chemo) therapy and surgery.

Methods

We performed a retrospective analysis of all patients who underwent Extremity STS excision from 2004 to 2014 (182 patients included). Patients’ data were collected from patients’ records. HRQoL was assessed by using EORTC QLQ-C30.

Results

A total of 182 patients underwent sarcoma resection. After neoadjuvant radiochemotherapy (RCT), the major-complication rate amounted to 28% (vs. 7%, no radiotherapy, p <  0.001). Major-complication rates after adjuvant radiotherapy (RT) occurred in 8% (vs. 7%, no radiotherapy, p = 0.265). Comparison QoL scores between treating with neoadjuvant RCT or without RT revealed significant worse scores with neoadjuvant RCT. Further stratification of disease control of these patients showed significant reduced scores in the group of disease-free patients with neoadjuvant RCT compared to irradiated disease-free patients.

Discussion

To date, there have only been a few investigations of QoL in STS. Retrospective study on quality of life have limitations, like a lack of baseline evaluation of QoL. Patient candidated to radiation therapy could have had worse QoL baseline due to more advanced disease. Disease status of the patients who answered the questionnaires could have been an influence of QoL and we could show reduced scores in the group of disease-free patients with neoadjuvant RCT, but not for the patients with recurrence or metastasis, so it is very hard to discriminate whether radiation therapy could really have an impact or not.

Conclusion

This study might assist in further improving the understanding of QoL in STS patients and may animate for prospective studies examining the oncological therapies impact on HRQoL.

Physical Function and Quality of Life After Resection of Mobile Spine Chondrosarcoma

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

(1) To assess patient-reported outcomes-physical function, pain, and quality of life-in patients who underwent resection of a mobile spine chondrosarcoma. (2) To assess complications (90 days), readmissions, reoperations, oncological outcomes, and neurologic status.

METHODS

Thirty-three patients with spinal conventional chondrosarcoma resection between 1984 and 2014 at one hospital were included. The primary outcome measures were-minimally 6 months after surgery-the EuroQol 5 Dimensions (EQ5D), PROMIS-Physical Function, PROMIS-Pain Intensity, and Oswestry (ODI) Disability Index, or Neck (NDI) Disability established in 14 out of 20 alive (70.0%) patients. Complications, readmission, reoperations, oncological outcomes, and neurological status were reported for the complete cohort of 33 patients.

RESULTS

After spine chondrosarcoma resection, patients (n = 14) reported worse physical function (median 43, range 22-61, P = .026), worse quality of life (median EQ5D 0.70, range 0.04-1, P = .022), and comparable pain intensity (median 47, range 31-56, P = .362) when compared with US general population values. The median NDI/ODI was 25 (range 0-72) indicating mild to moderate disability. Patients undergoing reoperation had worse patient-reported outcomes than those who did not. Eighteen (55.5%) out of 33 patients suffered complications (90 days), 14 (42.4%) had unplanned readmission, and 13 (39.4%) underwent reoperation. Intralesional resection was associated with increased readmission, reoperation, and recurrence rate.

CONCLUSIONS

Chondrosarcoma affects quality of life and physical function and its treatment frequently results in complications and reoperations. Our findings can be used to inform future patients about expected outcomes.

Maximizing Sacral Chordoma Resection by Precise 3-Dimensional Tumor Modeling in the Operating Room Using Intraoperative Computed Tomography Registration with Preoperative Magnetic Resonance Imaging Fusion and Intraoperative Neuronavigation: A Case Series

INTRODUCTION

The primary treatment for patients with sacral chordoma is en bloc surgical resection with negative margins, which has been shown to reduce local recurrence and tumor-related morbidity. Here we describe the use of intraoperative neuronavigation using preoperative spine magnetic resonance imaging fused to intraoperative computed tomography (CT) to create 3-dimensional tumor reconstructions in the operating room for intraoperative identification of bone and soft-tissue margins for maximal safe tumor resection.

METHODS

A single-institution retrospective chart review was completed to encompass our experience of 6 consecutive patients who had sacral chordoma resections using our described navigation protocol. We collected data on patient demographics, previous surgeries, radiation therapy, preoperative examination, spinal levels involved, dural involvement, estimated blood loss, surgery time, tissue diagnosis, follow-up, postoperative examination, complications, and recurrence. Primary outcome was en bloc resection with negative margins as planned preoperatively.

RESULTS

Negative surgical margins were achieved in 5 of 5 patients, who were preoperatively planned for en bloc resection with negative margins. The most common levels involved were S4-S5. All patients had a stable or improved neurologic examination after en bloc surgical resection. The average follow-up was 5.4 months ± 84.6 days. No patient had residual or recurrent tumor at last follow-up.

CONCLUSIONS

Magnetic resonance imaging-CT fusion and 3-dimensional reconstruction techniques using an intraoperative CT scanner with image-guided navigation to aid preoperative planning and surgical resection of sacral chordomas are not well represented in the literature. This technique can be used for planning en bloc surgical resections and for more precisely identifying tumor margins intraoperatively.

Quality of Life and Patient-Reported Outcomes Following Proton Radiation Therapy: A Systematic Review

Background

As costs of cancer care rise, the importance of documenting value in oncology increases. Proton beam radiotherapy (PBT) has the potential to reduce toxicities in cancer patients, but is relatively expensive and unproven. Evaluating quality of life (QOL) and patient-reported outcomes (PROs) is essential to establishing PBT's "value" in oncologic therapy. The goal of this systematic review was to assess QOL and PROs in patients treated with PBT.

Methods

Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)-guided systematic searches were conducted. The PubMed search engine was the primary data source, along with publications found from references of selected articles, and articles known to the authors published through 2017. Seventeen original investigations were found to have sufficient focus and relevance to be incorporated into the systematic review.

Results

Studies of skull base (n = 1), brain (n = 1), head/neck (n = 1), lung (n = 1), breast (n = 2), prostate (n = 8), and pediatric (n = 3) malignancies treated with PBT that met eligibility criteria were included. QOL did not deteriorate during PBT for skull base and after PBT for brain tumors, respectively. PROs were higher for PBT than photon-based radiotherapy for both head/neck and lung cancer. Patient-reported breast cosmesis was appropriate after PBT and comparable to photon modalities. PBT in various settings of prostate cancer displayed an expected post-therapy decline; one study showed improved PROs (rectal urgency, bowel frequency) for PBT, and two others showed PROs/QOL comparable with other modalities. Pediatric studies demonstrated improvements in QOL during therapy, with additional increases thereafter.

Conclusions

Based on limited data, PBT provides favorable QOL/PRO profiles for select brain, head/neck, lung, and pediatric cancers; measures for prostate and breast cancers were more modest. These results have implications for cost-effective cancer care and prudently designed QOL evaluation in ongoing trials, which are discussed. Future data could substantially change the conclusions of this review.

Symptom burden and life challenges reported by adult chordoma patients and their caregivers

PURPOSE

This study aims to characterize the symptom burden and life challenges that chordoma patients and their caregivers experience.

METHODS

In this cross-sectional study, we analyzed data from the Chordoma Foundation online community survey conducted in 2014. Frequency counts and percentages were calculated to determine the prevalence of self-reported symptoms and life challenges in the sample. We used Fisher's exact test to compare self-reported symptoms among subgroups with different disease status, tumor locations, and treatments received.

RESULTS

Among the survey participants, 358 identified themselves as chordoma patients and 208 as caregivers. The majority of the patients were over 45 years (72%), male (56%), educated beyond high school degree (87%), and from North America (77%). Skull base was the most prevalent tumor location (40%). Chronic pain (38%) was the most commonly reported symptom followed by depression or severe anxiety (35%), and chronic fatigue (34%). Among patients, the most commonly-reported challenges included delayed diagnosis (37%), long-term disability (33%), and change in career or reduced ability to work (33%). For caregivers, grief (55%), delayed diagnosis (47%), and difficulty helping the patient cope with his or her disease (45%) were most common.

CONCLUSIONS

Our study findings suggest a high symptom burden and life challenges among chordoma patients and their caregivers. This study provides preliminary, limited estimates of the prevalence of a wide range of self-reported symptoms and challenges that will inform the assessment of patient-reported outcomes in future clinical trials and help clinicians better manage chordoma patients' symptoms.

What questionnaires to use when measuring quality of life in sacral tumor patients: the updated sacral tumor survey

BACKGROUND CONTEXT

Patient-reported outcomes are becoming increasingly important when investigating results of patient and disease management. In sacral tumor, the symptoms of patients can vary substantially; therefore, no single questionnaire can adequately account for the full spectrum of symptoms and disability.

PURPOSE

The purpose of this study is to analyze redundancy within the current sacral tumor survey and make a recommendation for an updated version based on the results and patient and expert opinions.

STUDY DESIGN/SETTING

A survey study from a tertiary care orthopedic oncology referral center was used.

PATIENT SAMPLE

The patient sample included 70 patients with sacral tumors (78% chordoma).

OUTCOME MEASURES

The following 10 questionnaires included in the current sacral tumor survey were evaluated: the Patient-Reported Outcomes Measurement Information System (PROMIS) Global Item short form, PROMIS Pain Intensity short form, PROMIS Pain Interference short form, PROMIS Neuro-QOL v1.0 Lower Extremity Function short form, PROMIS v1.0 Anxiety short form, the PROMIS v1.0 Depression short form, the International Continence Society Male short form, the Modified Obstruction-Defecation Syndrome questionnaire, the PROMIS Sexual Function Profile v1.0, and the Stoma Quality of Life tool.

METHODS

We performed an exploratory factor analysis to calculate the possible underlying latent traits. Spearman rank correlation coefficients were used to measure to what extent the questionnaires converged. We hypothesized the existence of six domains based on current literature: mental health, physical health, pain, gastrointestinal symptoms, sexual function, and urinary incontinence. To assess content validity, we surveyed 32 patients, 9 orthopedic oncologists, 1 medical oncologist, 1 radiation oncologist, and 1 orthopedic oncology nurse practitioner with experience in treating sacral tumor patients on the relevance of the domains.

RESULTS

Reliability as measured by Cronbach alpha ranged from 0.65 to 0.96. Coverage measured by floor and ceiling effects ranged from 0% to 52% and from 0% to 30%, respectively. Explanatory factor analysis identified three traits to which the questionnaires that were expected to measure a similar construct correlated the most: mental health, physical function, and pain. Content validity index demonstrated low disagreement among patients (range: 0.10-0.18) and high agreement among physicians (range: 0.91-1.0) on the relevance of the proposed domains. Social health was identified by 50% of the commenting patients as an important yet missing domain.

CONCLUSIONS

The current sacral tumor survey is incomplete and time-consuming, and not all surveys are appropriate for the sacral tumor population. Our recommended survey contains less than half the questions and includes the newly recognized social health domain.

Recent advances in understanding and managing chordomas

Chordomas are rare primary bone tumors arising from embryonic remnants of the notochord. They are slow-growing, locally aggressive, and destructive and typically involve the axial skeleton. Genetic studies have identified several mutations implicated in the pathogenesis of these tumors. Treatment poses a challenge given their insidious progression, degree of local invasion at presentation, and high recurrence rate. They tend to respond poorly to conventional chemotherapy and radiation. This makes radical resection the mainstay of their treatment. Recent advances in targeted chemotherapy and focused particle beam radiation, however, have improved the management and prognosis of these tumors.

The 'radiation vacation': Parents' experiences of travelling to have their children's brain tumours treated with proton beam therapy

Proton beam therapy is a new form of radiotherapy. Little is known about patients' experiences of proton beam therapy and less about parents' experiences of children receiving treatment. Semi-structured interviews explored 10 parents' experiences of travelling from the United Kingdom to the United States to have their children's brain tumours treated with proton beam therapy. Thematic analysis uncovered themes of 'adjusting to the PBT routine', 'finding benefit in the situation' and 'readjusting upon returning home'. Parents' initial worries were elevated by travel, but they found benefit in their experiences, describing them positively. The periods before and after treatment were most difficult, illustrating a cycle from upset to calm, back to upset upon their return home.

Late local recurrence, at 19 and 17 years, of sacral chordoma treated by en bloc resection

Sacral chordoma (SC) is a malignant bone tumor with high risk of local recurrence (LR) even after en bloc resection, generally in the first 10 years after resection. We report two cases of late LR, at 17 and 19 years. Two male patients, aged 45 and 53 years, presented with large SC needing a combined approach for en bloc resection. Surgical margins were safe for the first patient and borderline for the second. The patients had yearly follow-up. The first patient developed LR on the posterior wall of the right acetabulum and the second developed LR in the right sciatic notch, at 17 and 19 years, respectively. These two cases of very late LR of SC advocate for yearly screening of patients even more than 20 years after resection.

LEVEL OF EVIDENCE

IV (case report).

Enhanced radiobiological effects at the distal end of a clinical proton beam: in vitro study

In the clinic, the relative biological effectiveness (RBE) value of 1.1 has usually been used in relation to the whole depth of the spread-out Bragg-peak (SOBP) of proton beams. The aim of this study was to confirm the actual biological effect in the SOBP at the very distal end of clinical proton beams using an in vitro cell system. A human salivary gland tumor cell line, HSG, was irradiated with clinical proton beams (accelerated by 190 MeV/u) and examined at different depths in the distal part and the center of the SOBP. Surviving fractions were analyzed with the colony formation assay. Cell survival curves and the survival parameters were obtained by fitting with the linear-quadratic (LQ) model. The RBE at each depth of the proton SOBP compared with that for X-rays was calculated by the biological equivalent dose, and the biological dose distribution was calculated from the RBE and the absorbed dose at each position. Although the physical dose distribution was flat in the SOBP, the RBE values calculated by the equivalent dose were significantly higher (up to 1.56 times) at the distal end than at the center of the SOBP. Additionally, the range of the isoeffective dose was extended beyond the range of the SOBP (up to 4.1 mm). From a clinical point of view, this may cause unexpected side effects to normal tissues at the distal position of the beam. It is important that the beam design and treatment planning take into consideration the biological dose distribution.